ENDODONTOLOGY ENDODONTOLOGY ENDODONTOLOGY ENDODONTOLOGY ENDODONTOLOGY
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Editorial
Original Research
4
A Comparison of the Relative Efficacies of Hand and RotaryInstruments in the Removal of Guttapercha from the Root Canalduring Retreatment using Stereomicroscope - An In-Vitro Study
“To Analyze the Distribution of Root Canal Stresses after SimulatedCanal Preparation of Different Canal Taper in Mandibular FirstPremolar by Finite Element Study – An In Vitro Study.”
A Comparative Evaluation of Cyclic Fatigue Resistance of Two RotaryNickel - Titanium Endodontic Systems - An In Vitro Study
Coronal Microleakage of Four Restorative Materials Used inEndodontically Treated Teeth as A Coronal Barrier - An In Vitro Study
In Vitro Evaluation of the Efficacy of Five Apex Locators
A Three-Dimensional Evaluation of Density and Homogeneity of RootCanal Obturation with Guttaflow® using Backfilling Technique inComparison with Conventional Lateral Compaction Technique usingSpiral Computed Tomography - An In Vitro Study
Comparative Evaluation of Radiopacity of Three Root Canal SealersUsing Conventional and Digital Radiographic Technique: An InvitroStudy
The Effect of File Sizes in the Presence of Sodium Hypochlorite andBlood on the Accuracy of Root Zx Apex Locator in Enlarged RootCanals - an In Vitro Study
Sealing Ability of Four Materials in the Orifice of Root Canal SystemsObturated With Gutta-Percha
Current Endodontics Literature
Dhanya Kumar N. M. 5-11Praveen GokulVasundhara Shivanna
Dhanya Kumar N. M. 12-21Abhishek SinghaniaVasundhara Shivanna
Dr. Gaurav Garg 22-26Dr. Sanjay MiglaniDr. Seema YadavDr. Sangeeta Talwar
Mithra N. Hegde 27-35Deepali S.
Niranjan A. Vatkar 36-42Sucheta SatheVivek Hegde
P. Senthil Kumar 43-50A. R. Vivekananda PaiKundabala M.
Swetha H. B. 51-56Shashikala K.
Paluvary Sharath Kumar 57-64Vasundhara Shivanna
Abhishek Parolia 65-70Kundabala M.Shashi Rasmi AcharyaVidya SaraswathiVasudev BallalMandakini Mohan
Sowmya Shetty 71-74
Volume: 20 Issue 2 December 2008 1-76
C O N T E N T S Page
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ENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYINDIAN ENDODONTIC SOCIETY(Estd. 1988)
FORM IVRULE 8
1. Place of Publication : Mangalore
2. Periodicity of publication : Biannual
3. Printer’s name, nationality and address : Srinivas Prabhu at IndianM/s. Sunline EnterprisesLower Car StreetMangalore - 575 001
4. Publisher’s name, nationality, and address : Dr. Anil Kohli IndianIndian Endodontic SocietyE-601, Greater Kailas - IIDelhi - 110 048
5. Editor’s name, nationality and Address : Dr. B. Sureshchandra IndianDepartment of Conservative Dentistry / EndodonticsA. J. Institute of Dental SciencesN. H.-17, Kuntikana, Mangalore - 575 004, Karnataka.
6. Name and address of the owner of the newspaper : Indian Endodontic SocietyE-601, Greater Kailas - IIDelhi - 110 048
Mangalore Signature of publisher.
Sd/-Dr. K. S. BangaSecretary General
Date: 15/6/2005 Indian Endodontic SocietyE-601, Greater Kailas - IIDelhi - 110 048
2
President:Dr. A. P. Tikku
Secretary General:Dr. K. S. Banga
Joint Secretary:Dr. J. Dhillon
Treasurer:Dr. S. H. Kulkarni
President elect:Dr. Ravi Kapur
Imm Past President:Dr. K. K. Wadhwani
Vice President:Dr. Sukesh KumarDr. S. BalagopalDr. S. Ramchandran
Executive committeePermanent members:
Dr.R.C.Kakkar Dr.Anil Kohli
Dr. Shenoy Kundabala Dr. Sharad KamatDr. Pradeep Jain Dr. Kapil LoombaDr. J. S. Baath Dr. Mithra N. Hegde
Members:
Dr. Roopa Nadig Dr. Moksha NayakDr. Arathi Ganesh Dr. Ida De AtaideDr. Gopi Krishna Dr. Ashwini Dobhal
Editor:Dr. B. Sureshchandra
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Editor:
Dr. B. Sureshchandra
Scientific Advisory Committee
Dr. Govila C. P. (India)
Dr. Gulabivala (U. K.)
Dr. Gutmann James L. (U.S.A.)
Editorial OfficeDepartment of Conservative Dentistry / EndodonticsA. J. Institute of Dental SciencesN.H.-17, Kuntikana, Mangalore - 575 004, Karnataka.Ph: 0824-2224938.Telefax: 0824-2224968.Clinic: 0824-2444041.E-mail: [email protected]
A publication of Indian Endodontic society
Editorial Board
Dr. Banga K. S.
Dr. Choudhary M.
Dr. Gopikrishna
Dr. Indira R.
Dr. Kandaswamy D.
Dr. Kohli Anil
Dr. Laxminarayanan L.
Dr. Mithra N. Hegde
Dr. Naseem Shah
Dr. Shenoy Kundabala
Dr. Shivanna V.
Dr. Tikku A. P.
Dr. Usha H. L.
Dr. Wadhvani K. K.
Abstracts
Dr. Sowmya Shetty
Endodontology is indexed in IndMED, the database of Indian Biomedical Journals, maintained by NationalInformatics Centre, Ministry of Information Technology, Govt. of India.
“Bibliographic details of the journal available in ICMR-NIC Centre’s IndMED database(http:// indmed.nic.in). Full text of articles, from 2000 onwards, being made available in MedlND database(http://medind.nic.in ).”
The journal is aIso listed with Indian National Scientific Documentation Centre (INSDOC), QutabInstitutional Area, New Delhi-110016 and English Serial Division, National Library, Kolkata.
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Editorial
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Dr. Spangberg is a household name among endodontists who are interested in pulp biologyglobally for his thoughts on PULPBIOLOGY. He belongs to that generation of endodontists who areconcerned about their speciality in the future and not only the present.
This is exactly what he has expressed quite frankly. I have for you a few glimpses of his gem ofan editorial.
An endodontist is supposed to be an expert on diseases thereof. Presently, however, the mostcommon therapy for the exposed and/or diseased pulp is a total amputation. This crude therapy isunfortunate, because today there are restorative materials that rarely require post retention for largerestorations, i.e., the root canal could still harbor a vital pulp if treated properly.
Pulp capping, in the way it is commonly practiced, has a low rate of success. This is despite thefact that past research has clearly outlined how it should optimally be done to result in a high rate of success. This performanceproblem can often be tracked back to lack of basic training in pulp biology and insufficient treatment experience in dentalschool.
Superficial pulp surgery on permanent teeth, although an endodontic procedure, is most frequently done in a generalpractice setting. Much research still remains to be done with this therapy to achieve a high level of success and predictability.This treatment appears to be of little interest, however, to endodontic organizations on any continent. The InternationalAssociation for Dental Research Pulp Biology group has also shown little interest in the clinical application of their basic scienceresearch efforts. This leaves an important form of therapy without any active and progressive interest group behind it. This is apity, because the tooth is probably better off with a functioning pulp that is healed by hard tissues rather than a root canalimplant.
During the last couple of years, much endodontic research has focused on implants and pulpal stem cells. A substantialamount of money is spent on these projects with little visible return for the endodontic patient with a diseased or injuredendodontium.
Endodontists are today infatuated by implants, and an undeserving amount of effort has been diverted from biologicendodontic research. We have been led to believe by implant proponents that the success rate of implants greatly surpasses thesuccess of endodontic treatment. That has without doubt jolted the profession. Recent available literature does not support thatconclusion, however. We often tend to compare the retention rate of implants with endodontic treatment success. This iscomparing apples to oranges. Success for implant procedures is vaguely defined. Therefore, the term “retention” is commonlyused when outcome is discussed. Implant retention does not exclude disease conditions. Recent studies clearly show that manyretained implants experience progressive bone loss, inflammation, and infection. Retention rate for time periods beyond 5 yearsnever exceed 92%. Comparable endodontic data of retained teeth can be gleaned from insurance data showing an endodonticretention rate of 96%-97% after 8 years, which is substantially better than implant data. In my opinion, the endodontists needsto be well informed about these issues and assure him/herself that the endodontic treatment provided is optimal and offers betteroutcome than implant replacement of restorable teeth. In addition, the endodontists needs to be less concerned about implants,which have their role in prosthodontics. Instead, they should broaden their role in pulpal diagnosis and the treatment of thedentin and the dental pulp. This would lead to new enhanced treatment options for the vital pulp beyond organ amputation.The intellectual component of endodontic practice would also be significantly improved by such changes.
Stem cell research and scaffolding are now buzzwords in basic science pulp research. What is more important to remember,however, is the fact that in most cases where endodontic procedures are done after pulp exposure, a fully developed pulpalready exists. Instead of amputating the organ and then rebuilding it, a better idea would be to treat and heal the diseased pulpthat is already established.
The endodontic community needs to enhance its clinical understanding of the vital pulp and dentin and embrace itstreatment. Endodontic postgraduate students need vastly more education in this area to support their future practices and tofunction as future leaders of pulp biology in their dental communities. This field of endodontology needs drastically moresupport both in specialist knowledge and research grant support. This is an area the American Association of EndodontistsFoundation ought to focus on as high priority. It may be exciting to attempt to build connective tissue inside the root canal butit is exceedingly more valuable to the patient to preserve a real pulp, which is already there.
In my personal opinion quite a few endodontists have become over night implantologists since they probably find endodonticsless financially viable. I would love to have the feed back on this editorial. You may send your opinions on [email protected]
Dr. B. Sureshchandra
Extract EDITORIAL; Who Cares About The Dental Pulp Triple ‘O’, Vol. 104, No. 5, Nov. 2007. LARZ S.W. SPANGBERG, SECTON EDITOR, ENDODONTOLOGY
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A Comparison of the Relative Efficacies of Hand andRotary Instruments in the Removal of Guttapercha fromthe Root Canal during Retreatment using Stereomicroscope- An In-Vitro Study
DHANYA KUMAR N. M *#PRAVEEN GOKUL **#VASUNDHARA SHIVANNA ***#
* PROFESSOR, ** POST- GRADUATE STUDENT, *** PROFESSOR AND HEAD, DEPARTMENT OF CONSERVATIVE DENTISTRY AND ENDODONTICS, COLLEGE OF DENTALSCIENCES (C.O.D.S.), DAVANGERE – 577004, KARNATAKA.
INTRODUCTIONNonsurgical endodontic retreatment consists
of cleaning, shaping, and three-dimensional
obturation of previously obturated root canals. It
is the treatment of choice for the management of
endodontic failures when access to the root canals
is feasible10. To successfully accomplish
retreatment, all of the obstructions - preventing a
direct straight line access to the root canals have
to be removed.
The major factors associated with endodontic
failure are the persistence of microbial infection in
the root canal system and/or the periradicular area.
The clinician is often misled by the notion that
procedural errors such as broken instruments,
ABSTRACT:The purpose of this study was to determine the efficiency of Greater Taper, ProTaper & RaCe rotary instrumentscompared with Hedstrom files for removal of guttapercha from root canal during retreatment following anendodontic failure.
60 mandibular premolars were divided into 4 groups, each group consisting of 15 teeth. Group 1: Hedstromfiles; Group 2: Greater Taper rotary (GT); Group 3: ProTaper; Group 4: with Reamer with alternate cutting edges(Race). The teeth were instrumented with K- type files and filled using lateral condensation technique withguttapercha and AH plus sealer. After repreparation with Gates Glidden drills and the test instruments the teethwere cleared. The area of remaining guttapercha/sealer on the root canal wall was measured from mesio-distaland bucco-lingual directions.
The RaCe group showed significantly less obturation material than System GT, ProTaper and H-files (p<0.001).There was no significant difference between System GT and ProTaper in removing guttapercha/sealer. RaCe tookthe least time for removing guttapercha/sealer (p<0.05). One ProTaper files and one H-file separated.
The study demonstrated that, RaCe NiTi rotary instruments cleaned the root canals after retreatment more efficientlythan ProTaper, System GT and H-files.
Keywords: Gutta-percha removal, Root canal retreatment, Nickel Titanium files, Rotary instrumentation.
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perforations, overfillings, underfillings, ledges and
so on are the direct cause of endodontic failure. In
truth, a procedural accident often impedes or makes
it impossible to accomplish appropriate intracanal
procedures5.
Removal of guttapercha can be obtained with
several techniques such as solvents, K-type or
Hedstrom files, Gates Glidden drills, heat pluggers3,
ultrasonic technique6, and lasers2. Additionally,
rotary instruments can also be used, such as the
inflexible XGP drills, the canal finder3, or more
recently flexible rotary nickel-titanium (NiTi) files
in a slow-speed handpiece.
More recently Ni-Ti retreatment rotary files
have been introduced which have proved to be
efficient and require less time when compared to
hand instrumentation1 although complete removal
of guttapercha has not been attained with these
instruments7. Currently, nickel titanium rotary
instruments like Reamer with alternate Cutting
edges (RaCe), ProTaper and Greater Taper (GT)
rotary have an important role in the removal of
guttapercha for their ability to simulate curved
canals & effectively produce well tapered root canal
form requiring less time.
Purpose of this study is to evaluate the
efficacy of H-file versus RaCe, ProTaper and Greater
Taper (GT) NiTi rotary instruments in the removal
of guttapercha from root canals, the time taken for
removal and procedural errors i.e. separated
instruments that occur during retreatment.
METHODOLOGYSelection of teeth: Sixty freshly extracted
human mandibular premolars were collected from
Dept. of Oral and Maxillofacial Surgery, College
of Dental Sciences, Davangere. Soft tissue and
calculus were mechanically removed from root
surfaces.
Access opening was made on each tooth with
high speed round diamond bur no.2 with air- water
spray. Working length was established l mm short
of root apex and the crowns were sectioned so that
working length was standardized to 18 mm. The
canals were prepared using step-down technique.
The cervical and middle-thirds were flared with
Gates Glidden drills 1, 2 and 3 in a telescopic
preparation. Canal instrumentation was completed
using K-type files with a master apical file size of
30. The canals were debrided using sodium
hypochlorite 5.25% and chlorhexidine 2%
irrigants.
The root canal of each tooth was dried with
paper points and obturated using lateral
compaction. A master gutta-percha cone size 30
was selected and tug-back was checked. AH Plus
sealer (Dentsply DeTrey) was mixed according to
the manufacturer’s instructions. The master cone
was coated with sealer and positioned into the
canal. Then accessory cones were laterally
compacted until they could not be introduced more
than 5 mm into the canal. The extension of the
root canal filling was limited to 14 mm from the
apex so that the volume of gutta-percha was nearly
equal for all teeth. The access cavities were filled
with the Cavit G (3M ESPE). All teeth were stored
in a humidor at 37°C for 2 weeks to allow complete
setting of the sealer.
Retreatment TechniqueAll samples were randomly divided into four
groups with 15 specimens each. All roots had 6
mm of obturation material removed from the
cervical part of the canal using Gates Glidden drills
A COMPARISON OF THE RELATIVE EFFICACIES OF HAND AND ROTARY INSTRUMENTS IN THE REMOVAL OFGUTTAPERCHA FROM THE ROOT CANAL DURING RETREATMENT USING STEREOMICROSCOPE - AN IN-VITRO STUDY
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2 and 3. After using the Gates Glidden drills, a
drop of eucalyptol solvent was intro-duced into
each canal to soften the gutta-percha. Two or three
addi-tional drops of solvent were applied as
required to reach the working length. Sodium
hypochlorite 5% and chlorhexidine 2% irrigations
were used after each instrument. Each root canal
was irrigated with a total of 30 ml sodium
hypochlorite and 30 ml chlorhexidine. System GT,
Pro-Taper and RaCe rotary instruments were driven
with a torque-con-trolled motor (X-Smart, Dentsply,
Maillefer) according to the manufacturer’s
instructions. The teeth were then rendered
transparent by first decalcifying them in 5% Nitric
acid then dehydrating them in 80% alcohol for
12hrs, 90% alcohol for 1hr and 100% alcohol for
3hrs. The teeth were then cleared using
Methylsalicylate.
Teeth were divided into 4 groups, each group
consisting of 15 teeth.
Group 1: (n=15) with Hedstrom files (Mani):ISO size 15 and 20 Hedstrom files were used for
deep penetration until they reached the working
length. The removal of gutta-percha was completed
using size 25 to 35 Hedstrom files in a
circumferential quarter-turn push-pull filing motion.
Group 2: (n=15) with Greater Taper (GT)NiTi rotary instruments (Dentsply Maillefer): GT
rotary instrument sizes 10.30, 08.30, 06.30, 04.30
were used in a crown-down technique according
to manufacturer’s instructions to remove the
guttapercha from the root canals.
Group 3: (n=15) ProTaper NiTi rotaryinstruments (Dentsply Maillefer): As suggested by
the manu-facturer, the gutta-percha was removed
by the following se-quence using light apical
pressure: Finishing files #3 (ISO size 30, taper
O.O9-O.O5), #2 (ISO size 25, taper 0.08-0.055),
and #l (ISO size 20, taper O.O7-O.O55) were used
in a crown-down technique to remove the gutta-
percha until the working length was reached.
Finishing files #2 and #3 were used again to the
working length to complete gutta-percha removal
and cleaning of the canal walls.
Group 4: (n=15) RaCe NiTi rotaryinstruments (FKG Dentaire) RaCe rotary
instruments sizes 10.40, 08.35, and 06.30 were
used in a crown-down approach. Instrument size
04.25 reached working length. RaCe files 02.30
and 02.35 were used for apical enlargement.
One set of instruments was used for
repreparation of five root canals. Files were wiped
regularly using gauze to remove obturation material
and debris. Preparation was deemed complete
when there was no gutta-percha/sealer covering
the instruments. Each root canal was prepared,
filled and retreated by the same operator to reduce
interoperator variability.
EvaluationFor all roots, three types of data were
recorded.
1. Canal Wall CleanlinessThe amount of gutta-percha/ sealer on the
canal walls was imaged in a standardized way in
bucco-lingual and mesiodistal directions and
measured in mm2 using image analyzer software
connected to a stereomicroscope with 6.5 X
magnification via a CCD-sensor. The evaluator was
blinded to group assignment.
DHANYA KUMAR N. M, PRAVEEN GOKUL, VASUNDHARA SHIVANNA
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2. Time for RetreatmentThe time elapsed from entering the canal with
the first Gates Glidden bur until the completion of
the reinstrumentation was measured with a
stopwatch.
3. Procedural ErrorsThe number and sort of fractured instruments
were recorded
Statistical analysis:Statistical analysis was performed for multiple
group comparisons by means of Kruskal-Wallis
ANOVA test followed by post hoc tests for pair
wise comparisons
RESULTSFrom the present in- vitro study the following
results were obtained:
1. Remaining obturation material was
observed in all groups. Imaged in a bucco-lingual
and mesio-distal directions, specimens treated with
RaCe showed least amount of remaining
guttapercha/sealer. The Hedstrom group, System
GT group and ProTaper group revealed significantly
larger areas of obturation material than RaCe group
(p<0.05). System GT group did not differ
significantly from ProTaper group (p>0.05) in the
removal of guttapercha/sealer from the root canals.(
Table 1, Graphs 1-4)
2. Regarding the mean time for retreatment
RaCe group took least time while System GT,
ProTaper and H-files required significantly more
time when compared to RaCe group. (Table 1,
Graph 5).
3. One ProTaper file (size F1) and one H-file
(ISO 25) separated during retreatment.
DISCUSSIONThe main goal of retreatment is to regain
access to the constriction by complete removal of
the root canal filling material, thereby facilitating
sufficient cleaning and shaping of the root canal
system and final obturation5, 8. Prognostic studies
have indicated that endodontic surgery or
extraction could be avoided by conventional
retreatment12.
Eucalyptol was used as a solvent in our study
as it has been reported to be a safe and efficient
alternative to chloroform11.
Different methodologies have been reported
during evaluation of remaining filling material
including longitudinal cleavage of teeth which may
displace filling material remnants; association of
longitudinal and transverse cleavage for evaluation
in thirds; and cleavage and photographic
recordings; visual examination through cleavage
and photography in association with radiographic
examination. The pro-blems with sectioning teeth
are that it can disturb the remaining filling material
and it is unpredictable. In the present study, the
roots were cleared to allow the measurement of
the area of residual obturation material because
remaining Gutta Percha or sealer might get lost by
splitting the roots longitudinally4.
In our study, direct visual scoring with the aid
of a stereomicroscope was adopted for the
evaluation of residual gutta-percha and sealer on
the canal walls, as it was considered a simple and
efficient assessment method9.
The results of our study suggest that RaCe NiTi
rotary instruments performed better when
compared to the other instruments. There was no
A COMPARISON OF THE RELATIVE EFFICACIES OF HAND AND ROTARY INSTRUMENTS IN THE REMOVAL OFGUTTAPERCHA FROM THE ROOT CANAL DURING RETREATMENT USING STEREOMICROSCOPE - AN IN-VITRO STUDY
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significant difference between System GT and
ProTaper in removal of guttapercha when viewed
in a mesio-distal direction. H-files performed poorly
when compared to rotary instruments. Instrument
separation occurred with H-files and ProTaper NiTi
rotary files.
The first two RaCe instruments (size 10.40 and
08.35) are made of stainless steel. Stainless steel
files have a better cutting efficiency than nickel-
titanium file. Probably this fact and the greater
taper of these two files compared to the ProTaper,
System GT and Hedstrom group might be a reason
for the quick and effective gutta-percha removal.
Other advantages of the RaCe instruments could
be the alternating cutting edges which eliminate
the unde-sirable screwing effect and the smooth
surface of the instruments that is caused by the
special chemical surface treatment. It is also
possible that the gutta-percha adhered less to the
flutes so that the file had a better cutting efficiency.
GT instruments with their taper-centric shaping
ability, Radial lands and U-type cross section
cleaned canal walls better and took less time than
H-files but was inferior than RaCe files and there
was not much difference when compared to
ProTaper.
With ProTaper group final apical preparation
diameter was of size 30 (F3) compared to final
apical diameter in the RaCe group which was of
size 35 therefore its cleaning ability was less when
compared to RaCe and there was not much
difference when compared to System GT although
the cleaning ability was better than hand files. Also
ProTaper shaping files proved to be impossible to
penetrate guttapercha without fractures of the files.
CONCLUSIONWithin the limitations of this in-vitro study the
following conclusions can be drawn from the
results of this study:
RaCe rotary system has alternating cutting
edges which efficiently removed debris from the
root canals and showed least remaining obturating
material. During retreatment the risk of instrument
fractures of ProTaper and H-files instruments seems
to be higher than that of RaCe and System GT, the
reason attributed could be that since RaCe files
utilize reduced working torque there was no
fracture of any instrument, and due to its inherent
instrument design wherein cutting efficiency is
increased RaCe took less time than ProTaper,
System GT and H-files.
Mean areas of remaining obturation material imaged in mesio-distal and bucco-lingual direction withstandard deviations (SD,mm2),mean time for retreatment (min) and number of fractured instruments
Method Mesio-distal Bucco-lingual Mean time Fractures
Mean SD Mean SD Mean SD
Hedstrom 5.49 0.37 4.44 0.63 12.29 1.16 1
System GT 3.81 0.58 2.37 0.32 9.31 0.15
ProTaper 3.79 0.24 2.93 0.38 8.23 0.11 1
RaCe 1.48 0.27 0.93 0.27 7.16 0.11
DHANYA KUMAR N. M, PRAVEEN GOKUL, VASUNDHARA SHIVANNA
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GRAPHS PHOTOS
FIG 4: STEREOMICROSCOPE READINGS WITH RaCe
BUCCO-LINGUALMESIO-DISTAL
FIG 3: STEREOMICROSCOPE READINGS WITH ProTaperBUCCO-LINGUALMESIO-DISTAL
Fig 2: STEREOMICROSCOPE READINGS WITH SYSTEM GT
BUCCO-LINGUALMESIO-DISTAL
BUCCO-LINGUALMESIO-DISTALFig 1: STEREOMICROSCOPE READINGS WITH H-FILES
A COMPARISON OF THE RELATIVE EFFICACIES OF HAND AND ROTARY INSTRUMENTS IN THE REMOVAL OFGUTTAPERCHA FROM THE ROOT CANAL DURING RETREATMENT USING STEREOMICROSCOPE - AN IN-VITRO STUDYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGY
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BIBLIOGRAPHY1. Barrieshi-Nusair KM. Gutta-percha retreatment: effectivenessof nickel-titanium instru-ments versus stainless steel hand files.J Endod 2002; 28:454-6.
2. D.Viducic, S. Jukic, Z. Karlovic, Z. Bozic, I.Miletic & I. Anic.Removal of guttapercha from root canals using an Nd-YAGlaser. Int Endod J 2003;36:670-3
3. Friedman S, Stabholz A, Tamse A. Endodontic retreatment:case se-lection and technique. Part 3: retreatment techniques.J Endod 1990; 16: 543-9.
4. Gergi R, Sabbagh C. Effectiveness of two nickel-titaniumrotary instruments and a hand file for removing gutta-perchain severely curved root canals during retreatment: an ex vivostudy. Int Endod J 2007;40:532-7
5. J.F. Siqueria Jr. Aetiology of root canal treatment failure:why well-treated teeth can fail. Int Endod J 2001; 34:1-10.
6. Krell KV, Neo J. The use of ultrasonic endodonticinstrumentation in the re-treatment of a paste-filled endodontictooth. Oral Surg Oral Med Oral Pathol 1985:60:100-2.
7. Kosti E, Lambrianidis T, Economides N, Neofitou C. Ex vivostudy of the efficacy of H-files and rotary Ni-Ti instruments toremove gutta-percha and four types of sealer. Int Endod J2006;39:48-54
8. Mandel E, Friedman S. Endodontic Retreatment: A RationalApproach to Root Canal Reinstrumentation. J Endod1992;11:565-9
9. Schirrmeister JF, Wrbas KT, Meyer KM, Altenburger MJ,Heiiwig E, Efficacy of differ-ent rotary instruments for gutta-percha removal in root canal retreatment. J Endod2006;32:469-72.
10. Stabholz A, Friedman S. Endodontic retreatment: caseselection and technique. Part 2: treatment planning forretreatment. J Endod 1988; 14:607-14.
11. Tamse A, Unger U, Metzger Z, Rosenberg M. Gutta-perchasolvents: a comparative study. J Endod 1986;12:337-9Tasdemir T, Er K, Yildirim T, Celik D. Efficacy of three rotaryNiTi instruments in removing gutta-percha from root canals.Int Endod J 2007;41:191-6
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“To Analyze the Distribution of Root Canal Stresses afterSimulated Canal Preparation of Different Canal Taper inMandibular First Premolar by Finite Element Study – An InVitro Study.”
DHANYA KUMAR N. M. *ABHISHEK SINGHANIA **VASUNDHARA SHIVANNA ***
* PROFESSOR, ** POST GRADUATE, *** PROFESSOR & HEAD, DEPARTMENT OF CONSERVATIVE DENTISTRY AND ENDODONTICS, COLLEGE OF DENTAL SCIENCES(C.O.D.S.), DAVANGERE – 577004, KARNATAKA.
ABSTRACTWas to Investigate stress distribution patterns in simulated biomechanically prepared mandibular first premolarswith four different tapers at two different compaction forces and an occlusal load with finite element analysis.
Six recently extracted, intact, non-carious, undestroyed mandibular premolars similar in-straight root canals wereselected. Four finite element models were designed on the software varying only in canal taper of mandibularfirst premolars. Gutta-percha was compacted by vertical condensation technique in three separate verticalincrements under two different vertical compaction forces that are 10N and 15N. Finite element meshes weregenerated with this model by using soft ware to know the pattern of distribution of radicular stresses duringobturation. At last access opening will be filled by using simulated restorative material (composite). A masticatoryload of 50N was applied; again Finite element meshes were generated.
The highest circumferential and radial stresses were found during compaction of first gutta percha increment,while an increase in taper reduced the stress level for the same compaction force. During obturation, higherstresses were found at the canal surface, using the smallest taper, in apical third, during the first gutta perchaincrement and gradually decreased along the canal length. Root stresses during occlusal load application generatesthe highest stresses at external root surface and concentrate at cervical third, an increase taper size caused onlyslight lower root stresses.
With increasing taper root stresses decreased during root canal obturation. Root fracture at the apical third islikely initiated during obturation. Root fracture at the cervical third is likely initiated during occlusal load.
KEYWORDS: canal taper, compaction force, finite element analysis, occlusal load, root stresses, verticalcompaction, vertical root fracture.
INTRODUCTIONAfter endodontic therapy, teeth are more prone
to vertical root fracture because of loss of moisture
(9%) and become more brittle when compared to
vital tooth. Vertical root fracture can occur in teeth
during or subsequent to endodontic therapy. The
causative factors for vertical root fractures are the
compaction of gutta percha, placement of intra-
radicular posts, masticatory load, trauma, and
traumatic injuries. Vertical root fractures are more
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common during the vertical condensation
technique of obturation and often complicate or
prevent subsequent restorative procedures. These
fractures a count for the most serious complication
of root canal treatment and often result in tooth
extraction because of poor prognosis6.
It is generally accepted that the strength of an
endodontically treated tooth is directly related to
the amount of remaining tooth structure. Several
treatment procedures such as caries removal, access
preparation, instrumentation of root canal, irrigation
of root canal with sodium hypochlorite, and long
term intracanal dressing with calcium hydroxide
lead to loss of tooth structure or weaken the root
dentine. The prevalence of Vertical root fracture is
not equally distributed over the different tooth types.
Maxillary and mandibular premolars have both
recorded a high prevalence6.
Stresses distribution in endodontically treated
teeth can be measured by photoelastic method,
strain gauge and instron testing machine. But the
major disadvantage of all these methods in stresses
can measured at selected sites only and not inside
the root canal7.
Finite element analysis is an engineering
method for the numerical analysis of complex
structures based on their material properties
(Young’s modulus and Poisson ratio) to determine
the distribution of stresses and strain pattern induced
in internal structure of tooth / bone / implants / any
living tissue5.
The purpose of the present study is to
investigate stress distribution patterns in simulated
biomechanically prepared mandibular first
premolars with four different tapers at two different
compaction forces and an occlusal load with finite
element analysis.
METHODOLOGYTwenty four samples have been derived from
six recently extracted, intact, non-carious,
undestroyed mandibular first premolars. Six x-ray
films were used to know the canal curvature of six
mandibular first premolars. Optical scanner was
used to digitalize the external surface morphology
of six extracted mandibular first premolars on
computer software that has been designed for Finite
Element analysis.
GROUPINGFour finite element models were designed on
the software varying only in canal taper of each
mandibular first premolar. Each model carried six
specimens. These models were assigned as: Group
1 with taper 2%, Group 2 with taper 4%, Group 3
with taper 6% and Group 4 with taper 12%.
All other aspects of the models were held
constant including boundary conditions, material
properties, compaction forces during filling and
magnitude / direction of applied occlusal load. The
tooth model was created by digitizing the external
surface of extracted human mandibular first
premolar with an optical scanner in combination
with Finite element analysis computer software
(NISA). A straight root was chosen for this study to
eliminate effects due to canal curvature. Gutta-
percha were compacted by vertical condensation
technique in three separate vertical increments
(apical 1/3, middle 1/3, cervical 1/3) under two
different vertical compaction forces that are 10
Newton and 15 Newton for each increment. 200µm
thick periodontal ligament layer and a surrounding
bone volume to support the root were created on
DHANYA KUMAR N. M., ABHISHEK SINGHANIA, VASUNDHARA SHIVANNA
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finite element model.
Subsequently, a simulated standard access
opening was made in the crown, and root canals
were created that represented 2%, 4%, 6% and
12%. The 4% and 6% tapers were chosen for
clinical relevancy, as these are incorporated into
commonly used nickel–titanium rotary files and are
representative of clinically imparted tapers on the
canal space. The drastic 12% tapered canal
preparation was chosen arbitrarily to simulate the
effects of excessive canal preparation. All models
were created with a final apical preparation of 0.35
mm at the point of constriction, 0.5 mm from what
would be clinically perceived as the radiographic
apex. All canal preparations were straight. Isotropic
properties were applied for the dentine, periodontal
ligament, supporting bone volume, gutta-percha
and restorative composite. The periodontal ligament
was modeled as a soft incompressible connective
layer.
An arbitrary range of friction coefficients (0.10–
0.25) were evaluated to account for the friction
between the gutta-percha and the root canal wall.
The development of radicular stresses was analyzed
during three consecutive filling steps as well as for
an occlusal load after the root filling using finite
element analysis. Warm gutta-percha was
compacted in three separate vertical increments
until the canal was filled. The gutta-percha
temperature at the start of compaction was 60oCo
and was gradually cooled down during the filling
procedure until it reached 37oCo. In this analysis,
two vertical compaction forces were tested at 10
and 15 N for each increment. The forces were
applied by means of a simulated plugger. The
plugger surface had slightly rounded edges and a
tip-diameter that was 0.5 mm smaller than the canal
diameter at each compaction increment.
After complete simulated obturation, the
simulated access space was closed using a simulated
bonded restorative composite. The composite was
filled; a 50 N occlusal load was applied in the
buccolingual plane to the triangular ridge of the
buccal cusp (functional cusp) at an angle of 600 with
the vertical axis. The value of the occlusal force
was chosen to represent a relatively high biting force
and buccal cusp was selected because it is the
functional cusp and lingual cusp is rudimentary in
mandibular first premolar. During the analysis, the
root was supported by the surrounding bone volume
via the soft periodontal ligament layer, which was
given incompressible properties to approximate
fluid behavior.
The mean value, standard deviation and one
way ANOVA was used to evaluate the site of
maximum stress concentration. Statistical analysis
(ANOVA) was used for multiple comparison and
correlation analysis to assess the relationship
between different taper and radicular stresses.
RESULTSFour finite element models were designed on
the software varying only in canal taper as- Group
1 with taper 2%, Group 2 with taper 4%, Group 3
with taper 6% and Group 4 with taper 12%.
In group 1 with taper 2%, the highest mean
value and standard deviation was at apical third
followed by middle and cervical third under
compaction force of 10 newton (Table-1).
From group 1 to group 4, the highest mean
value and standard deviation was at apical third of
“TO ANALYZE THE DISTRIBUTION OF ROOT CANAL STRESSES AFTER SIMULATED CANAL PREPARATION OFDIFFERENT CANAL TAPER IN MANDIBULAR FIRST PREMOLAR BY FINITE ELEMENT STUDY – AN IN VITRO STUDY.”
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2% taper (group-1) followed by middle and cervical
third of 2% taper under compaction force of 10
Newton (Table-1). Similar results were obtained in
different groups under compaction force of 15
Newton (Table-2).
During occlusion load application (50N) in
different group, highest mean was recorded in group
1 with 2 % taper and least in group 4 with 12%
taper. Highly significant pairs were group 1 & 2,
group 1 & 3 and group 1 & 4 (Table 3).
On comparing the different tapers with each
increment under compaction force of 10N shows
the significant pairs apical third and coronal third
for taper 2% ( P<0.05), apical third and middle
third, apical third and coronal third for taper 6%
and 12% taper (P<0.001) (Table 4).
Also on comparing the different tapers with
each increment under compaction force of 15N
shows the significant pairs apical third and middle
third, apical third and coronal third for taper 4%,
6% and 12% taper (P<0.001) (Table 5)
Results: Highest circumferential and radial
stresses were found during compaction of first gutta
percha increment, while an increase in taper
reduced the stress level for the same compaction
force. During obturation, higher stresses were found
at the canal surface and in apical third with smallest
taper and during the first gutta percha increment
and gradually decreased along the canal length.
Root stresses distribution during occlusal load
application generated the highest stresses at external
root surface that concentrated at the tooth surface
of the cervical third, an increase taper size caused
only slight lower root stresses.
DISCUSSIONThe prognosis of endodontically treated teeth
depends not only on the success of the endodontic
treatment but also on the amount of remaining
dentine tissue, and the nature of final restoration.
Fractures of restored endodontically treated teeth
are a common occurrence in clinical practice and
it is the second most frequent identifiable reason
for loss of endodontically treated teeth4.
The increased susceptibility of fracture in
endodontically treated teeth had been attributed due
to the increased brittleness of dentine, due to loss
of moisture - Helfer et al reported that the moisture
content of dentine from endodontically treated teeth
was about 9% less than teeth with vital pulp.
However, Papa et al emphasized the importance
of conserving the bulk of dentine to maintain the
structural integrity of post-endodontically restored
teeth. Other studies have also emphasized that the
loss of tooth structure is the key reason for the
increase in fracture predilection of endodontically
treated teeth1.
The fracture resistance of the restored
endodontically treated tooth is a function of the
strength of the root (taper of prepared canal) and
remaining coronal tooth structure.34 Tooth fracture
has been described as a major problem in dentistry,
and is the third most common cause of tooth loss
after dental caries and periodontal disease.
Generally, an endodontically treated tooth
undergoes coronal and radicular tissue loss due to
prior pathology, endodontic treatment, and/or
restorative procedures. The loss of dentine tissue
will compromise the mechanical integrity of the
remaining tooth structure1.
Mandibular premolars and maxillary premolars
DHANYA KUMAR N. M., ABHISHEK SINGHANIA, VASUNDHARA SHIVANNA
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have both recorded a high prevalence of vertical
root fracture in endodontically treated teeth21.
Vertical root fracture seems to be a more common
reason for extraction of endodontically treated
teeth.2
Root canal biomechanical preparation can be
done by a hand file or rotary file. Canal preparation
involves dentin removal and may compromise the
fracture strength of the roots25. The development
of new design features such as varying tapers,
noncutting safety tips and varying length of cutting
blades in combination with the metallurgic
properties of alloy nickel-titanium have resulted
in a new generation of instruments and concepts33.
Although no significant difference in the fracture
load of hand and rotary nickel titanium canal
preparation could be demonstrated3.
Given increasing acceptance of rotary
instrumentation as a technique for cleaning and
shaping the canal space, it is important to examine
the effect of specific tapers imparted by rotary
instrumentation of the canal wall as it relates to
vertical root fracture. The clinician must make a
decision to use instruments which have an
inherently larger or smaller taper based on the
architecture present in a given canal. Choosing a
smaller taper may reduce the risk of procedural
accidents and untoward events during cleaning and
shaping, but it may compromise the cleanliness of
the canal system and placement of filling material.
Choosing too large a taper may increase canal
cleanliness (especially in the coronal and mid-root
areas), but may also increase the potential for strip
perforations, other procedural accidents, and may
predispose the root to vertical fracture if, indeed,
greater reduction of root structure increases stress
in the canal wall.7
Assessment of stress levels patterns in root
canal can be measured by a number of ways that
includes Instron universal machine, photoelastic
method, strain gauges and most recent one is finite
element analysis10. Assessment of stress levels by
measuring deformation patterns inside the root
canal is extremely difficult, leaving investigators
with indirect external observations at best
extremely difficult. Finite element analyses have
been utilized to address these difficulties and gain
insight into internal stress distributions 7,2.
Finite element analysis which is an
engineering method for the numerical analysis of
structure based on their material properties has
been used for stress analysis. Material properties
such as the Young’s modulus and Poisson Ratio
can be utilized by computer generated analyses to
describe the mechanical behavior of a structure5.
CONCLUSIONWith in the limitation of this finite element
analysis, the following conclusions were drawn.
During simulated obturation, root stresses
decreased as the root canal taper increases and
stresses were greatest at the apical third and along
the canal wall. After simulated root canal obturation
was completed and occlusal force was applied, the
generated stresses were greatest at the cervical
portion of the root surface, and decreased as taper
increases. It was likely that vertical root fractures
initiated at the apical third as result of compaction
forces, whereas vertical root fractures initiated
cervically were a manifestation of subsequent
masticatory load on the root canal obturated teeth.
However additional in-vivo and in-vitro tests
and clinical trial are desirable in order to elucidate
the accuracy of finite element analysis.
“TO ANALYZE THE DISTRIBUTION OF ROOT CANAL STRESSES AFTER SIMULATED CANAL PREPARATION OFDIFFERENT CANAL TAPER IN MANDIBULAR FIRST PREMOLAR BY FINITE ELEMENT STUDY – AN IN VITRO STUDY.”
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10 NEWTON OF COMPACTION FORCE
Apical 1/3 Middle 1/3 Cervical 1/3
Tapers Mean SD Mean SD Mean SD
2% 0.789 0.087 0.716 0.067 0.669 0.025
4% 0.713 0.041 0.657 0.022 0.587 0.032
6% 0.667 0.025 0.603 0.029 0.608 0.134
12% 0.646 0.015 0.566 0.030 0.484 0.025
Table-1: Compaction Force of 10N on Apical, Middle and Cervical Third in Different Tapers.
15 NEWTON OF COMPACTION FORCE
Apical 1/3 Middle 1/3 Cervical 1/3
Tapers Mean SD Mean SD Mean SD
2% 1.267 0.373 1.135 0.256 0.988 0.012
4% 1.051 0.038 0.972 0.019 0.869 0.051
6% 0.976 0.018 0.893 0.032 0.767 0.059
12% 0.946 0.017 0.847 0.033 0.540 0.110
Table-2: Compaction Force of 15N on Apical, Middle and Cervical Third in Different Tapers.
Tapers Mean
2% 4.782
4% 3.291
6% 3.007
12% 2.510
P* Value, Sig P<0.001 HS
Significant Pairs** I&II, I&III,I&IV
Table-3: Comparision of Mean Occlusion Load of 50N in Different Tapers.
Tapers Apical 1/3 Middle 1/3 Cervical 1/3 P* Value, Sig Significant Pairs**
2% 0.789 0.716 0.669 P<0.05 S At & Ct
4% 0.713 0.657 0.608 P>0.05 NS -
6% 0.667 0.603 0.587 P<0.001 HS At &Mt, At & Ct
12% 0.646 0.566 0.484 P<0.001 HS At &Mt, At & Ct
Table-4: Comparison Of Different Tapers With Each Increment To Evaluate Significant Pair Under CompactionForce Of 10N.
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Tapers Apical 1/3 Middle 1/3 Cervical 1/3 P* Value, Sig Significant Pairs**
2% 1.267 1.135 0.988 P>0.05 NS -
4% 1.051 0.972 0.869 P<0.001 HS At &Mt, At & Ct
6% 0.976 0.893 0.767 P<0.001 HS At &Mt, At & Ct
12% 0.946 0.847 0.540 P<0.001 HS At &Mt, At & Ct
Table-5: Comparison Of Different Tapers With Each Increment To Evaluate Significant Pair Under CompactionForce Of 15N.
Fig 1 apical third g.p filling on model with taper 2% under compaction forces (10n) fig. 2 (15n). Fig 3.middle third g.p filling on model with taper 2% under compactionforces (10n).fig 4 (15n). Fig 5cervical third g.p filling on model with taper 2% under compaction forces (10n). Fig 6 (15n). Fig 7 occlusal load of 50n applied on model(2%), after filling the access cavity with composite (stress graph ).fig 8 occlusal load of 50n applied on model (2%), after filling the access cavity with composite(displacement graph). Fig 9 apical third g.p filling on model with taper 4% under compaction forces (15n). Fig 10 (10n). Fig 11middle third g.p filling on model with taper4% under compaction forces ( 15n). Fig 12 (10n).
“TO ANALYZE THE DISTRIBUTION OF ROOT CANAL STRESSES AFTER SIMULATED CANAL PREPARATION OFDIFFERENT CANAL TAPER IN MANDIBULAR FIRST PREMOLAR BY FINITE ELEMENT STUDY – AN IN VITRO STUDY.”
5 6 7 8
9 10 11 12
1 2 3 4
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Fig 13 cervical third g.p filling on model with taper 4% compaction forces (15n) fig 14 (10n) fig 15 occlusal load of 50n applied on model (4%), after filling the accesscavity with composite(stress graph ) fig 16 (displacement graph) fig 17 apical third g.p filling on model with taper 6% compaction forces ( 15n) fig 18 (10n) fig 19 middlethird g.p filling on model with taper 6% under compaction forces ( 15n). Fig 20 (10n). Fig 21 cervical third g.p filling on model with taper 6% compaction forces (15n) fig22 10 n fig 23 cervical third g.p filling on model with taper 6% compaction forces (10n) occlusal load of 50n applied on model (6%), after fiiling the access cavity withcomposite (stress graph ) fig 24occlusal load of 50n applied on model (6%), after fiiling the access cavity with composite (displacement graph)
DHANYA KUMAR N. M., ABHISHEK SINGHANIA, VASUNDHARA SHIVANNA
13 14 15 16
17 18 19 20
21 22 23 24
25 26 27 28
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MATERIAL PROPERTIES APPLIED IN THE STRESS ANALYSIS (FEA)Material Elastic Reference Poisson’s Reference
Modulus (GPa) Ratio Reference
Enamel 84 Craig & Powers 0.33 Farah et al. (1989)(principal direction) (2002)
Enamel 42 Craig & Powers 0.31 Farah et al. (1989)(transverse plane) (2002)
Dentine 14.7 Sano et al. (1994) 0.50 Farah et al. (1989)
Periodontal ligament 0.00118 Dyment and Synge 0.30(1935)
Bone 0.49 Moroi et al. (1993) 0.30 Farah et al. (1989)
Gutta-percha Temperature 0.30 (0 C0) 0.35Dependent (30 C0) 0.40 (60 C0)
Restorative composite 14 Willems et al. (1992) 0.24 Craig & Powers0.24 Craig & Powers (2002)(2002)
GRAPHS
“TO ANALYZE THE DISTRIBUTION OF ROOT CANAL STRESSES AFTER SIMULATED CANAL PREPARATION OFDIFFERENT CANAL TAPER IN MANDIBULAR FIRST PREMOLAR BY FINITE ELEMENT STUDY – AN IN VITRO STUDY.”
Fig 25 apical third g.p filling on model with taper 12% under compaction forces (10n). Fig 26 (15n). Fig 27 middle third g.p filling on model with taper 12% undercompaction forces (10n) fig 28 (15n). Fig 29 cervical third g.p filling on model with taper 12% under compaction forces (10n). Fig 30 (15n). Fig 31 occlusal load of50n applied on model (12 %), after fiiling the access cavity with composite (stress graph ) fig 32 occlusal load of 50n applied on model (12 %), after fiiling the accesscavity with composit e (displacement graph)
29 30 31 32
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BIBLIOGRAPHY1) Aviad Tamse. Vertical root fractures in endodonticallytreated teeth: diagnostic signs and clinical management.Endodontic Topics 2006;13:84–94.
2) B. D. Rundquist & A. Versluis. How does canal taper affectroot stresses? International Endodontic Journal. 2006;39:226-237.
3) Chankhrit Sathorn, Joseph E.A. Palamara, and Harold H.Messer. Effect of root canal size and external root surfacemorphology on fracture susceptibility and pattern: A FiniteElement Analysis. J Endod 2005;31:288-291.
4) Chankhrit Sathorn, Joseph E.A. Palamara, and Harold H.Messer. A comparison of the effect of two canal preparationtechnique on root fracture susceptibility and pattern, J Endod2005;31:283-287.
5) Linda J.-William, Peter G. Fotos, Vijay K. Goel, James D.Spivey, Eric M. Rivera and Satish C. Khera. A-three–dimensional finite–element stress analysis of an endodonticprepared maxillary central incisor. J Endod 1995; 21:362-367.
6) Tannaz Zandbiglari et al. Influence of instrument taper onthe resistance to fracture of endodontically treated roots. Oralsurg oral med oral path oral radio endo 2006;101:126-31.
7) Yeera Lertchirakarm et al. Finite element analysis and straingauge studies of vertical root fracture.J Endod 2003;29:529-534.
DHANYA KUMAR N. M., ABHISHEK SINGHANIA, VASUNDHARA SHIVANNA
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A Comparative Evaluation of Cyclic Fatigue Resistance ofTwo Rotary Nickel - Titanium Endodontic Systems - An InVitro Study
DR. GAURAV GARG *DR. SANJAY MIGLANI **DR. SEEMA YADAV ***DR. SANGEETA TALWAR ****
ABSTRACT:The purpose of this study was to compare the fracture resistance of two different rotary Ni Ti instrument systemsdue to cyclic fatigue. The instruments compared were RaCe (FKG, La- Chaux De Fonds, Switzerland) and a newrotary system - Varitaper (Endomax, Equinox, Holland). The cyclic fatigue testing was conducted with the instrumentrotating freely at two different angles of curvature 45Ú & 90Ú with maximum curvature at 5mm from the tip.Total 60 instruments were tested in the two groups for both angles of curvature. The instruments were rotated at350 rpm using the ATR motor (Dentsply, Maillefer) set at maximum torque, until fracture occurred. The timeuntil fracture was recorded in seconds by using a stopwatch, and the number of rotations to fracture was thencalculated and results were statistically analyzed. RaCe (FKG, La- Chaux De Fonds, Switzerland) performedsignificantly better than Varitaper (Endomax, Equinox, Holland) in cyclic fatigue testing.
* PG Student, ** Asst. Professor, *** Assoc.Professor, **** Professor & Head of Department, Department of Conservative dentistry & Endodontics, Maulana Azad Instituteof Dental Sciences ,MAMC Campus, New Delhi - 110002. Correspondence: Dr. Gaurav Garg (e-mail- [email protected])
INTRODUCTIONRoot canal preparation in narrow and curved
canals is a great challenge. Rotary Ni- Ti files can
be used to prepare curved canals as they are 2-3
times more elastic and flexible in bending & torsion
and have Superior resistance to torsional fracture
compared with similar size stainless steel files1.
Despite the advantages of rotary Ni- Ti instruments,
concern has been expressed by many authors and
clinicians about the potential for rotary Ni- Ti
instrument to fracture within the root canal system
during endodontic treatment2-4. Although
instrument fracture may not affect the prognosis
when endodontic treatment can be performed to a
high technical standard, it may present a problem
if microbial control is compromised3 or should
excessive removal of tooth structure be required
to eliminate the fragment4.
Endodontic instrument fracture within canal
is a complex event. Fracture occurs without
warning and without any visible defects of previous
permanent deformation. So Visible inspection is
not reliable for Ni-Ti instruments.Two modes of
fracture of rotary Ni-Ti endodontic instruments have
been identified in the clinical situation: Torsional
fracture and Flexural fracture5. Among these
flexural fatigue is an important factor in a clinical
point of view. An understanding of factors that
contribute to instrument fracture is important in
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preventing its occurrence. These include the
following: Root canal anatomy both in terms of
radius & Degree of curvature (most Important),
operator proficiency, operational speed and torque,
previous use, sterilization procedures and cross
sectional area and design of the instrument6. Many
different rotary systems are available with difference
in cross sectional shape and design, Taper and total
number of instruments within system. But it is quite
difficult to determine the best one.
RaCe(FKG, La- Chaux De Fonds, Switzerland)
is one of the system that has been used for severely
curved canals with success due to its extreme
flexibility and Good shaping ability with little
transportation7,8.
Varitaper (Endomax, Equinox, Holland)
comprises of six safe ended instruments including
three apical finishers with a gradual increasing taper
of 3-6% and variable helical angles. It has a unique
crosscut design over cutting edge to reduce stress
on instrument and for efficient debris removal.
Like RaCe (FKG, La- Chaux De Fonds,
Switzerland) the cross section design of Varitaper
is triangular but with slightly positive rake angle
for efficient cutting of dentin as per manufacturer’s
specifications.
Fig.1- Armamentarium
The aim of this study was to evaluate &
compare the cyclic flexural fatigue resistance of
RaCe(FKG, La- Chaux De Fonds, Switzerland) and
recently introduced rotary Ni-Ti system;
Varitaper(Endomax, Equinox, Holland).
MATERIALS AND METHODSThe instruments evaluated were RaCe (FKG,
La-Chaux De Fonds, Switzerland) and Varitaper
(Endomax, Equinox, Holland)(fig.1). All files were
of tip size ISO 25 and 25 mm in length, but there
was a difference in the taper among the two (fig.2).
Fig. 2- instruments evaluated-upper-RaCe,lower-Varitaper.
RaCe has a continuous taper of 0.02
throughout and Varitaper has a gradual increasing
taper from 3-6%.
A system was used that allowed fatigue test to
be conducted in a manner similar to that of Youssef
et al (1999)9. It comprises of three cylindrical steel
blocks (one supporting block and two shaping
block) attached on a 6mm thick acrylic sheet which
was held vertically with the help of a vise.
The positions of the shaping blocks was
adjusted in order to get the desired degree of
curvature (45Ú and 90Ú) in the instrument in such
a manner that maximum curvature was at 5mm
from the tip (fig. 3 and fig.4).
The angle of curvature was calculated by
Schneider’s method10, which defined the angle of
curvature by drawing a line parallel to the long
DR. GAURAV GARG, DR. SANJAY MIGLANI, DR. SEEMA YADAV, DR. SANGEETA TALWAR
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axis of the canal and the outer line from the apical
foramen to intersect with first line at a point wherein
the canal began to leave the long axis of the canal.
Fifteen instruments were tested in each of the
four experimental groups and for both angles of
curvature to give a total of 60 instruments tested
(table 1).
The instruments were rotated at 350 RPM
using the ATR motor (Dentsply, Maillefer).
The time until fracture was recorded in
seconds by using a stopwatch, and the number of
rotations to fracture was than calculated using the
simple formula: No. of rotation to fracture= 350/
60 X time taken to fracture (in sec.).
Because the study was a direct comparison of
fatigue resistance among groups, a separate control
group was not required.
Results of cyclic fatigue test were analyzed
by using Paired t test (SPSS Software) with level of
significance at p< 0.05.
RESULTSThe number of rotations to fracture, when the
instruments were rotated at a 45Ú and 90Úangle
of curvature, are presented in table 2 and mean &
standard deviation is provided in table 3. Pairwise
comparison showed that the number of rotations
to failure for RaCe was significantly greater than
that of VariTaper at both angles of curvature 45Ú
and 90Ú with p-value .004 and .002 respectively.
(Table 4).
Table 1
Experimental groups and no. ofinstruments in each group (n)
Group 1 Group 2 Group 3 Group 4
VariTaper VariTaper RaCe RaCe(45Ú), n=15 (90Ú), n=15 (45Ú), n=15 (90Ú), n=15
A COMPARATIVE EVALUATION OF CYCLIC FATIGUE RESISTANCE OF TWO ROTARY NICKEL -TITANIUM ENDODONTIC SYSTEMS - AN IN VITRO STUDY
Fig.4- Instrument at 90Úcurvature
Fig.3-Instrument at 45Úcurvature
ENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGY
25
Table 2 : Table of number of rotations atfracture at both angles of curvature for bothinstruments
VariTaper RaCe
Samples 45O 90O 45O 90O
1 332 146 350 154
2 340 150 356 150
3 330 142 352 148
4 315 145 349 154
5 351 152 341 152
6 328 148 346 146
7 340 143 343 153
8 345 151 346 158
9 330 147 349 151
10 337 138 341 143
11 324 149 348 150
12 348 146 351 151
13 352 154 342 148
14 339 143 348 152
15 336 149 350 156
Table 3 : Table of means and standarddeviations of number of rotations to fracture
VariTaper RaCe
45O 90O 45O 90O
Mean 336.47 146.87 347.47 151.07
St. D 10.29 4.24 4.32 3.84
Pairs Mean Diff. St. D P -value
Pair 1 Varitaper 11 12.47 0.00445Ú- RaCe 45Ú
Pair 2 Varitaper 4.2 4.33 0.00290Ú- RaCe 90Ú
Table 4: Table of pairwise comparison amonggroups, mean difference, standard deviationand p value
DISCUSSIONThe present study confirmed that the number
of rotation to fracture an instrument largely depends
on the degree of curvature with more incidence of
breakage at greater degree of curvature as
concluded by other studies11, 12.
In endodontic treatment, Biomechanical
preparation is very important as the outcome is
largely depends on proper cleaning and shaping.
A more tapered preparation results in enhanced
cleaning as there is more removal of infected dentin
and also endodontic irrigants can reach more
apically and results in better microbial control and
better debridement and also good quality
obturation13.
Varitaper has more taper (3-6%) as compared
to RaCe (0.002) and theoretically might results in
better apical preparation with gradually increasing
taper. But in severely curved canals the instruments
with greater taper generally fracture earlier as
compared to 0.02 tapered instruments due to
reduced flexibility14. The results of present study
also confirmed this fact.
The cross cut design incorporated in the
Varitaper system might results in less cyclic fatigue
than other instruments of similar taper as some of
the values of Varitaper at 45Ú & 90Úare similar to
as that of RaCe. As this was an in vitro study clinical
trials should be carried out for more appropriate
comparison.
As Varitaper is a new system, further studies
are required to analyze it with other various rotary
systems according to various aspects.
CONCLUSIONUnder the limitations of present study we
DR. GAURAV GARG, DR. SANJAY MIGLANI, DR. SEEMA YADAV, DR. SANGEETA TALWAR
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26
concluded that RaCe performed significantly better
than Varitaper at both degree of curvature.
References:1. Walia H, Brantley W A, Gerstein H. An initial investigationof the bending and torsional properties of nitinol root canalfiles. JOE 1988; 14:346-51.
2. Huismann M, Peters OA,Dummer PMH. Mechenicalpreparation of root canals: shaping goals, techniques andmeans. Endod Topics 2005; 10:30-76.
3. Spili P, Parashos P, Messer HH. The impact of instrumentfracture on outcome of endodontic treatment. J Endod 2005;31:845-50.
4. Souter NJ, Messer HH. Complications associated withfractured file removal using an ultrasonic technique. J Endod2005;31:450-2
5. Sattapan B, Nervo GJ, Palmara JEA, Messer HH. Defects inrotary nickel-titanium files after clinical use. J Endod2000;26:161-5.
6. Margot E Anderson, John WH, Peter parashos. Fractureresistance of electropolished rotary nickel titanium endodonticinstruments. J Endod 2007;33:1212-16.
7. Samantha, Renato Cremonse, Susan Bryant, Paul Dummer.Shaping ability of RaCe rotary Nickel-Titanium instruments
in simulated root canals. J Endod 2005;31:460-67.
8. F Paque, U Musch, M Hulsmann. Comparison of root canalpreparation using RaCe and Protaper rotary Ni-Ti instruments.IEJ 2005;38:8-16.
9. Youssef Haikel, Rene Serfaty, Geoff Bateman, BernardSenger, Claud Allemann. Dynamic and cyclic fatigue of enginedriven rotary Nickel-Titanium endodontic instruments. JEndod 1999;25:434-440.
10. Schneider SW. A comparison of canal preparation instraight and curved root canals. Oral Surg 1971;32: 271-5.
11. Gabriela Zelada, P. Varela, B. Martin, Jose G., F.Magan,Saem Ahn. The effect of rotational speed and the curvatureof root canals on the breakage of rotary endodonticinstruments. JOE 2002; Vol.28, No.7.
12. Margot E.Anderson, John W.H. Price, Peter Parashos.Fracture resistance of electropolished rotary Nickel-Titaniumendodontic instruments. JOE 2007; Vol. 33, No. 10: 1212-1216.
13. Najia Usman, J.Craig, J. Gordon. Influence of instrumentsize on root canal debridement. JOE 2004; Vol.30, No.2.
14. Y. Haikel, Rene Serfaty, G. Bateman, B. Senger, C.Allemann. Dynamic and cyclic fatigue of engine driven rotaryNickel-Titanium endodontic instruments. JOE 1999; Vol.25,No. 6: 434-40.
A COMPARATIVE EVALUATION OF CYCLIC FATIGUE RESISTANCE OF TWO ROTARY NICKEL -TITANIUM ENDODONTIC SYSTEMS - AN IN VITRO STUDY
ENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGY
Coronal Microleakage of Four Restorative Materials Usedin Endodontically Treated Teeth as A Coronal Barrier - AnIn Vitro Study
DEEPALI S. *MITHRA N. HEGDE **
* PG Student, ** Head of the Department, Department of Conservative Dentistry & Endodontics, A.B. Shetty Memorial Institute of Dental Sciences, Deralakatte, Mangalore.
ABSTRACTThe present in vitro study was undertaken to evaluate sealing ability of access restoration using, four differentdentin adhesives under composite with conventional glass ionomer cement and resin modified glass ionomercement as intracoronal barrier
65 extracted human maxillary premolars were randomly divided into 15 teeth each in 4 experimental groupsand 5 intact teeth each in control group. Following the biomechanical preparation,all teeth were obturated usingProtaper gutta percha points and AH plus sealer. Once the sealer set, about 3mm of gutta-percha was removedfrom canal orifice in all the teeth. The base was placed till canal orifice extending 1mm coronally.
All the specimens were thermocycled for 500 cycles at 50 – 550 c for 30 sec, and then placed in Rhodomine 6Gfluorescent dye for 24 hrs. The coronal leakage was measured under a fluorescent microscope. Data obtainedfrom the study were subjected to statistical analysis using one way Anova Test and Tukey’s HSD test.
RESULTS - It showed statistically significant difference in coronal leakage among all the groups, but with nostatistically significant difference seen between high strength glass ionomer cement (Group I and Group II) andKetac N 100 (group III and Group IV when placed as intraorifice barrier.
CONCLUSION - Under the limitations of the present study the following conclusions were made that, Compositerestoration with Xeno III adhesive and Ketac N 100 as intraorifice barrier showed better coronal sealing ability inaccess cavities.
INTRODUCTIONThe most common cause for failure of root
canal therapy is apical percolation or microleakage
due to an inadequate apical seal. This allows
periapical fluids, proteins, and bacteria access to
the root canal. Through this interchange an
inflammatory reaction is initiated which often
results in radiographic or clinical signs of failure of
root canal therapy. The question arises that if apical
microleakage is a cause of endodontic failure, what
role might coronal microleakage plays in prognosis
of root canal treatment. 1
Endodontic obturation is often thought of only
in terms of an effective apical seal. However, the
coronal seal may be equally important for the
ultimate success of endodontic treatment. The
apical seal may be adversely affected if coronal
seal is lost or becomes defective.2
A three dimensional filling of the root canal
27
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28
system will prevent the penetration of
microorganism and toxins from the oral cavity via
the root canal into the periradicular tissues. Weine
has indicated that improper restoration leads to loss
of more endodontically treated teeth than actual
failure of endodontic therapy. Good coronal
restoration resulted in significant healing of
periradicular inflammation as compared to well
obturated root canals.3
Composite resins are the most common
choice for restoring access cavities. They can be
bonded to tooth structure and most restoratives,
and can provide a good match of color and surface
gloss. Bonded composite materials can also
strengthen existing coronal or radicular tooth
structure, at least in the short time. Traditional glass
ionomer cements are self cure and have very little
polymerization shrinkage, although less than
composite resins. Conventional glass ionomer
cement and resin modified glass ionomer materials
are useful for bulk filling access cavities.
Placement of material over the coronal gutta-
percha to act as a barrier to coronal microleakage
would be advantageous. The ideal intraorificebarrier has not been identified yet, or perhaps, not
even developed.4
Hence there is a need to conduct a study to
assess the coronal microleakage with permanent
access restorative materials with an intraorifice
barrier.
METHODOLOGY65, straight two rooted maxillary premolars
with mature root apices and single canal extracted
on periodontal or orthodontic grounds were used.
Teeth with gross caries involving the root, cracks
on the root surface and for exceptionally short and
thin roots were excluded. All teeth were stored in
10% neutral buffered formalin for at least 2 weeks
and then in distilled water until they were tested.
The teeth were thoroughly cleaned with an
ultrasonic scaler. Radiographs were taken to
confirm the presence of two canals.
Coronal access was achieved and working
length for all teeth was determined by subtracting
0.5 mm from the length at which the file tip
extruded apically. All the teeth were prepared using
ProTaper files in a variable tip crown – down
sequence to an apical size of 0.25 mm (master
apical file size .25 mm) at 0.5 mm from the canal
terminus or apical foramen. All the teeth were
instrumented with the ProTaper instruments
according to the manufacturer’s direction.
15% EDTA (Glyde, Dentsply Co.) was used
to coat the ProTaper files while they were used.
The root canals were irrigated in between each file
with 2.5% sodium hypochlorite (Vensons India)
and physiologic saline using a long 27 gauge
needle alternatively. The smear layer was removed
using 3 ml of 17% EDTA followed by a final flush
with 3 ml of 2.5% sodium hypochlorite. Upon
completion of instrumentation, the canals were
dried utilizing absorbent points. Upon completion
of instrumentation, the canals were dried utilizing
absorbent points. A master cone radiograph was
taken and obturated using F2 gutta percha cone
and accessory cones with lateral condensation
using AH Plus root canal sealer.
Access restoration placement –All the 65 prepared teeth were randomly
divided into four experimental groups of 15 teeth
MITHRA N. HEGDE, DEEPALI S.
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29
each as I, II, III and IV respectively, and control
group of 5 teeth.
Control group: 5 teeth used were intact teeth
with periapical seal and coated with Nail Varnish
completely
Intra orifice space preparation - After drying
the access, 3mm of gutta percha was removed from
the coronal orifice (cemento-dentinal junction)
using heated endodontic hand plugger of ISO size
# 30. in all the teeth except control group.
Intraorifice Barrier–Group I and Group II: 30 teeth were used in
which 3mm intraorifice space was restored with
High Strength Glass Ionomer Cement extending
1mm coronally.
Group III and Group IV: 30 teeth were used
in which 3 mm intraorifice space was Primed for
15 seconds and then air dried restored with Ketac
N 100 and cured for 10 seconds extending 1 mm
coronally.
Access Restoration:
Group I: 15 teeth used were etched with 37%
phosphoric acid for 15 Seconds, Prime& Bond NT
adhesive was applied and cured for 10 sec.
Group II: In 15 teeth, Clearfil S3 adhesive was
applied and left for 20 seconds, then Light cured
for 10 sec.
Group III: 15 teeth, G Bond was applied and
left for 10 seconds and then light cured for 10 sec.
Group IV: 15 teeth, Xeno III was mixed
according to manufacturer’s Instructions, left
undisturbed for 20 sec and light cured for 10 sec.
All the four groups were then restored with
Filtek Z 350 and cured for 20 seconds. Teeth were
then placed in artificial saliva for 20 days, later
subjected to thermocycling for 500 cycles at 5- 550c
for dwell time 30 seconds. The samples were dried
for 24 hours.
DYE LEAKAGEFor evaluation of the quality of the coronal
seal, the teeth were subjected to dye leakage.
Experimental groups were coated with two layers
of nail varnish except at 2 mm area around access
restoration.
All teeth were then immersed in Rhodomine
6G fluorescent dye which was freshly prepared
(According to the manufacturer’s instruction) for
48 hours. After this time the excess dye were
washed off and varnish gently scraped away from
the coronal surface.
The coronal portion was then sectioned
buccolingually in a longitudinal direction with a
diamond disc under running water.
MICROSCOPIC EVALUATIONColor photographs were taken of the sectioned
samples using Nikon S-10 camera attached to a
fluorescent microscope and later the pictures were
transferred to a personal computer. Digitized
images were analysed using Image analysis
software. The maximum degree of dye penetration
was recorded for each section, the degree of
leakage was determined from the coronal till the
apex and the dye penetration was scored with
scoring criteria.19
SCORING CRITERIA0 = No leakage detected
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1 = Slight, just reaching the pulp chamber
2 = Moderate, penetrating halfway into pulp
chamber
3 = Extensive, with leakage extending upto
the floor of the pulp chamber
4 = Gross, extending into the root canal and/
or furcation
RESULTSThe data obtained evaluating the coronal seal
was subjected to statistical analysis using Anova
test. The computed value of p is < 0.005, which
indicates statistically significant difference between
the groups under study. All the experimental groups
exhibited maximum leakage in composite while
the least leakage was in glass ionomer to radicular
dentin.
The mean values showed that the highest
leakage in composite was seen in Group IV
followed by Group III, while least was seen in
group I. At the interface between the glass ionomer
cement and interface, the mean value showed
highest leakage in Group III and least was in Group
IV. At the level of intraorifice barrier highest leakage
was observed in Group I and least in Group IV.
Furthermore, the data was subjected to
Tukey’s HSD test to determine the intergroup
comparison. This test was done to compare the
two groups, it was observed that there was no
statistically significant difference when Group I was
compared with Group II (p value = 0.347), and
there was no statistically significant difference when
Group III was compared with Group IV and (p value
= 0.076).
DISCUSSIONThe success of endodontic therapy depends
on a thorough chemomechanical preparation for
removal of necrotic debris and bacteria from the
root canal followed by sealing the root canal to
prevent ingress of bacteria and tissue fluids. Dow
and Ingle stated that failure most commonly occurs
due to inadequate apical seal. Studies have shown
that a good coronal seal is equally important.5
Swarthz et al found that the failure rate was twice
as high in cases without an adequate coronal
restoration compared to cases which were
adequately restored 6
Fractured teeth and leaking or missing
temporary restorations are encountered clinically,
leaving the access to the canals open to the oral
cavity. Thus the potential exists for oral fluids and
bacterial contamination of the root canal space due
to dissolution of the coronal seal23.
There are several methods that might possibly
prevent microleakage through obturated root canals
in the event the coronal restoration becomes
defective or is lost. These include placement or an
additional material such as IRM into the canal
orifices after removal of portion of the gutta percha
and sealer, sealing the entire chamber floor with a
restorative material, or use of a root canal filling
method that provides a seal without the addition
of other sealing materials.
In the present study, Multirooted maxillary
premolar teeth with two root canals were selected
to minimize anatomical variation, allow
standardization and since accessory canals and
lateral canals in furcation area though are not
routinely obturated, may affect the prognosis of
MITHRA N. HEGDE, DEEPALI S.
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31
endodontically treated tooth due to close proximity
of furcation to gingival sulcus. 10
The use of tracers is one of the oldest and most
common methods of detecting microleakage in
vitro. Fluorescent dyes are found to be useful as
tracers because they are detectable in dilute
concentrations, inexpensive, are easy to
photograph, permit more reproducible results,
contrast sharply with the natural fluorescence of
teeth, permit direct observation of the total marginal
interface during evaluation and scoring of leakage,
and being nontoxic, can be used safely.16
Thermocycling is a standard protocol in
restorative literature when bonded materials are
evaluated, simulating in vivo aging by subjecting
them to cyclic exposures of hot and cold
temperatures. Resin composite restorative materials
and adhesive systems are sensitive to
thermocycling. Thermocycling stress may induce
a significant amount of bond fatigue and
microleakage at the tooth/restoration interface.
Marginal leakage is believed to be result of a
difference in coefficient of thermal expansion
between restorative material and tooth.15.hence in
accordance with study done by Korsali et al the
samples were thermocycled 500 cycles at 50-550C
for 30 seconds.
The ideal properties of an intraorifice barrier
have been proposed by Wolcott et al. to include
the following characteristics: a) easily placed b)
bonds to tooth structure c) seals against
microleakage d) distinguishable from natural tooth
structure and e) does not interfere with final
restoration. Placement of an additional material
such as Glass ionomer cement or amalgam in to
the canal orifices after removal of a portion of the
gutta percha and sealer upto 3mm has several
advantages.
1. The coronal 3mm of the canal is an ideal
small cavity that is surrounded by intact tooth
structure and can be easily sealed.
2. There is no occlusal load in the orifice area.
3. There are no esthetic considerations in this
method, because the material is placed within the
canal. 14
This is more appropriate on posterior teeth;
however on anterior teeth, more care is necessary
because the suggested material can cause
discoloration of teeth or interfere with future
bonding agents that are usually used for the teeth.
Glass ionomer cements are made primarily
of alumina, silica and polyacrylic acid and self
curing materials. They are the only restorative
materials that depend primarily on a chemical bond
to tooth structure. They form an ionic bond to
hydroxyapatite at dentin surface and also obtain
mechanical retention from micro porosities in the
hydroxyapatite.
Glass ionomer cements form lower initial
bond strength to dentin than resins, (3-7Mpa). But
unlike resins they form a “dynamic” bond as the
interface is stressed, bonds are broken, but new
bonds form .this is one factor that allows glass
ionomer cements to succeed clinically, despite
relatively low bond strength. But they could not
overcome the following disadvantages: 1) they set
slowly and must be protected from moisture and
dehydration during the setting reaction which is
not completed for 24 hours, 2) they rely on ionic
bonding to hydroxyapatite, strong acids should be
CORONAL MICROLEAKAGE OF FOUR RESTORATIVE MATERIALS USED IN ENDODONTICALLYTREATED TEETH AS A CORONAL BARRIER - AN IN VITRO STUDY
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32
avoided because they totally eliminate mineral
from dentin surface. Hence could be sensitive to
total etch adhesives for bonding.18 The present study
showed no statistical significance difference
between sealing ability of high strength glass
ionmer cement groups.
Nano resin modified glass ionomer cement
contains an acid- degradable glass and aqueous
solutions of polyacid and monomeric ingredients
such as 2-hydroxyethyl methacrylate (HEMA). The
nano resin modified glass ionomer” restorative
further contains a unique combination of two types
of surface treated nanofillers (approximately 5-25
nm) and nanoclusters (approximately 1.0 to 1.6
microns). The setting reaction of the cement starts
immediately upon mixing as an acid –base
reaction. Free radical polymerization of the
monomeric components is then initiated by visible
light irradiation. Each acrylate group can take part
independently in the chain reaction, but the net
effect is the formation of a covently cross-linked
three-dimensional network. The set cement then
consists of interpenetrating networks of, poly
(HEMA) and polyacrylate salts. This photochemical
reaction reduces the early sensitivity to moisture
and dehydration associated with the early stage of
the acid-base setting reactions of GICs. They have
the clinical advantage of extended working time,
increased mechanical strengths by as much as two
or three times compared to GICs. The primer,
contains HEMA modifies the smear layer which
facilitate better penetration of polyacrylic acid
aiding into increase bond strength compared to
conventional GICs.23 The present study evaluated
no statistical significance difference between
sealing ability of Ketac N 100 groups.
Bonding to dentin with resin is more complex
than bonding to enamel. Dentin consists of 50%
inorganic mineral by volume, 30% organic
components and 20% fluid. The wet environment
and relative lack of mineralized surface made it a
challenge to develop materials that bond to dentin.
Microleakage of the restoration is a more important
issue in endodontically treated tooth. None of the
current adhesives systems are capable of preventing
microleakage over long time.
The current study concluded that all the
adhesive system showed microleakage after 20
days, while Xeno III has shown the least leakage
compared to Clearfil S3, Prime&Bond NT, G Bond.
Self etch adhesives system have become
increasingly popular in the last decade the
combination of etchant and primer into one system
is advantageous in that it reduces the application
time and technique –related sensitivity. On the
other hand, there is on going debate regarding the
efficacy of bonding to enamel with self-etch
adhesives systems. While some authors support the
manufactures recommendations that the adjunctive
use of phosphoric acid etching is necessary when
bonding to uncut enamel, while others argue that
the bond strengths of self etch adhesives are equal
to the bond strength of total-etch adhesives to
unground enamel.20,22
Contemporary self etch adhesives systems can
be categorized as mild, moderate and aggressive
depending on the acid dissociation constants acidic
resin monomers used and the concentration of
monomers present in the adhesives.
Van Meerbeek et al attributed least leakage is
due to it being a intermediary self etch adhesive
MITHRA N. HEGDE, DEEPALI S.
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33
with acidic PH of 1.5. This acidic nature results in
better micromechanical interlocking to dentin
compared to strong self etch adhesives. It is also
suggested that the residual hydroxyappatite at the
hybrid layer base may still allow for chemical
intermolecularinteraction.25
Clearfil S3 shows better seal among the self
etching adhesives but slightly lower than Xeno III
(p>0.05). The reason attributed to this is the
presence of MDP. This functional phosphate
monomer to a large extent, determines its actual
bonding efficiency and stability. MDP has two
hydroxyl groups that may bind to calcium. Yoshida
et al reported that MDP tightly adheres to
hydroxyapatite and that its calcium salt hardly
dissolved in water. Moreover MDP causes minimal
dissolution of smear plugs and limited opening of
tubules, reducing dentin permeability. It also
facilitates penetration, impregnation,
polymerization and entanglement of monomers
with demineralized dentin to form a relatively thick
hybrid layer. So the lower dye penetration observed
in the samples could be attributed to difference in
chemical compositions of self etch adhesives.24
According to the study conducted by Van
Meerbeek et al, at the dentin interface the
phosphoric acid treatment exposes microporus
network of collagen that is totally deprived of
hydroxyappatite, EDAX have confirmed that nearly
all calcium phosphates were removed or at least
became under detection limit. As a result, the
primary bonding mechanism of Etch & rinse
adhesives to dentin is primarily diffusion-based and
depends on hybridization or infiltration of resin
within the exposed collagen fibril scaffold, which
should be as complete as possible. True chemical
bonding is rather unlikely, because the functional
groups of monomers may have only weak affinity
to the “hydroxyappatite – depleted” collagen. Such
challenging monomer- collagen interaction could
be the prime reason for microleakage. This is in
accordance to the present study which concludes
that, Prime & Bond NT showed the maximum
leakage .25
G bond adhesive (HEMA free adhesive)
showed the highest leakage, the reason could be
attributed to the recent study phase where
separation among the adhesives compositions was
confirmed as droplets entrapped during solvent
evaporation from HEMA free adhesives. That
phenomenon could be explained by the
evaporation of solvents such as acetone, which
affected the balance of solvents and resin monomer
and caused water separate from the composition
of the adhesive.17 Spherical blisters within the resin
film may be the outcome of the residual free water
not completely evaporated and entrapped at the
interfacial level. The convergence of small blisters
into large ones tends to produce honeycomb
structures that may jeopardize the bonded
interface.
In the present study, Filtek Z 350 showed
leakage in all the groups it is in accordance with
study done by Korsali et al, the reason was
attributed to the sealing performance of nano
composite which is affected in access cavities by
cavity configuration (6:1), dimensional changes like
polymerization shrinkage or thermal/hydroscopic
expansion and bonding capacity of resin.
Clinically, the quality of an access restoration
cannot be determined. Although experimental
studies cannot exactly reproduce clinical
CORONAL MICROLEAKAGE OF FOUR RESTORATIVE MATERIALS USED IN ENDODONTICALLYTREATED TEETH AS A CORONAL BARRIER - AN IN VITRO STUDY
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34
MITHRA N. HEGDE, DEEPALI S.
Table IDYE LEAKAGE
Shows comparison of the mean coronal leakage of fivedifferent group’s
BAR GRAPH SHOWS COMPARISON OFMEAN APICAL LEAKAGE OF THE THREEGROUPS BY ANOVA TEST
Table 1: Comparison of the Coronal Leakage of all theExperimental Groups and control Group.
conditions, and the relationship of in vitro leakage
measurements to the in vivo situation has not yet
been established, the most reasonable way of
testing the efficacy of coronal restoration is
extrapolation of the data obtained from in vitro
studies to clinical conditions and long term clinical
evaluation of the results. 13
CONCLUSIONIn the present study microscopic evaluation
was done to analyze the extent of coronal dye
leakage using Rhodamine 6G fluorescent dye of
access restoration in endodontically treated with
a Composite material ( Filtek Z350) using Prime &
Bond NT, Clearfil S3, G bond and Xeno III
adhesives with High strength glass ionomer
cements and Ketac N 100 as an intra orifice barrier.
The following conclusions were drawn,√ The coronal seal is better when Ketac N 100
is used as intraorifice barrier.
√ Maximal coronal sealing is critical for
successful endodontic therapy. In this simulated
clinical setting, composite restoration with Xeno
III as bonding adhesive and Ketac N 100 as
intraorifice barrier offered the highest probability
for achieving a maximal coronal seal. Figure 2: Fluoroscent Microscope.
Figure 3: Fluorescence of the dye showing extent of coronalleakage.
Figure 1: Bar graph shows comparison of mean coronalleakage of the five groups by ANOVA.
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4. Arnold.A.D, Wilcox.L.R: Restoration of endodonticallytreated anterior teeth: An evaluation of coronal microleakageof glass ionomer and composite resin materials. J ProsthetDent 1990; 64:643 – 646.
5. Torabinejad.M, Borasmy.MS, Kettering.J.D: In vitrobacterial penetration of coronally unsealed endodonticallytreated teeth. J Endod 1990; 16(12):566 – 569.
6. Magura.M.E, Kafrawy.A.H, Brown.C.E, Newton.C.W:Human saliva coronal microleakage in obturated root canals:An in vitro study. J Endod 1991; 17(7):324 – 331.
7. Khayat A, Lee S-J, Torabinejad M. Human saliva penetrationof unsealed obturated root canals. J Endo 1991; 17: 324-331.
8. Shetty M. B. Fracture resistance of intact and endodonticallyprepared human mandibular molars restored with threedifferent combinations of restorative materials- An in-vitrostudy. Endo Society Intern Endo Journal.1993.
9. Wolcott.J.F, Hicks.L.M, Himel.V.T. Evaluation of pigmentedintraorifice barrier in endodontically treated teeth. J Endod1999; 25(9):589-592.
10. Tewari.S, Tewari.S. Evaluation of coronal microleakagein endodontically treated multirooted teeth. Endodont 2000;12:18-22.
11. Wolanek.G.A, Loushine.R.J, Weller.N.R, Kimbrough.F.W,Volkmann.K.R. In vitro bacterial penetration of endodonticallytreated teeth coronally sealed with dentin bonding agent. JEndod 2001; 27(5):354-357.
12. Belli.S, Zhang.Y, Pereira P.N.R, Pashley.D.H. Adhesivesealing of pulp chamber. J Endod 2001; 27(8):521-526.
13. Ozturk B, Ozer F, Belli S. An in vitro comparison ofadhesive systems to seal pulp chamber walls. Int Endo J 2004;37:297-306.
14. Scott.M.M, Scott.B, Goodell.G. The effect ofthermocycling on a colored glass ionomer intracoronal barrier.J Endod 2005; 31(7):5266-528
15. Korsali.D, Ziraman.F, Ozyurt.P, Cehrali.B. Microleakageof self etch primer/adhesives in endodontically treated teeth.J Am Dent Assoc 2008; 138(5):634-640
16. Bahareh Fathi, James Bahcall, James S. Maki. An In VitroComparison of Bacterial Leakage of Three CommonRestorative Materials Used as an Intracoronal Barrier. J Endod.2007; 33(7):872-874.
17. Saunders.WP, Saunders.EM: Coronal leakage as a causeof failure in root canal therapy: a review. Endod DentTraumato1994; 10:105-108.
18. Schwartz R.S, Fransman R. Adhesive dentistry andendodontics : materials, clinical strategies and procedures forrestoration of access cavities : a review. J Endo 2005;31:151-165
19. Leinfelder, K. Current Developments in Dentin BondingSystems. JADA 1993; 124: 40-42.
20. Christensen.G. Self-etching primers are here. J Am DentAssoc 2001; 132(7):1041-1043
21. Smith.G. Surface deterioration of glass-ionomer cementduring acid etching: An SEM evaluation. J Op. Dent 1988;13:3-7.
22. Tay.F, Pashley.D.H. Aggressiveness of contemporary selfetching systems. I: depth of penetration beyond dentin smearslayers. Dent Mat 2001; 15:715-718.
23. Darvell.B, Yelamanchili.A. Network competition in resin-modified glass ionomer cement. Dent Mat 2008; 24:1065-1069.
24. Burke.T.F.J. What’s new in dentine bonding self-etchadhesives. Dent update 2004; 12:580-589.
Meerbeek.B.V, et al. Adhesion to Enamel and dentin: currentstatus and future challenges. J Op Dent 2003; 28(3):215-235.
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CORONAL MICROLEAKAGE OF FOUR RESTORATIVE MATERIALS USED IN ENDODONTICALLYTREATED TEETH AS A CORONAL BARRIER - AN IN VITRO STUDY
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In Vitro Evaluation of the Efficacy of Five Apex Locators
NIRANJAN A. VATKAR *SUCHETA SATHE **VIVEK HEGDE ***
* Second year post graduate student, ** Professor, *** Head of Department, Department of Conservative Dentistry and Endodontics at M. A. Rangoonwala College of DentalSciences and Research Centre, Azam Campus, Pune-1.
ABSTRACTToday in this field of new era with lot many innovations coming up daily, endodontics has taken a new paradigmshift. The earlier root canal technique of ‘biomechanical preparation’ is now changing into ‘chemobiomechanicalpreparation’. Today’s root canal treatment not only depends on proper cleaning and shaping procedures but alsoproper reaching of the irrigant upto the desired working length. Therefore it is absolutely essential to determineexact working length to achieve an optimum cleaning and shaping procedures. From the beginning of endodontics,many modalities and techniques have been devised for the determination of working length. With increasedunderstanding of the relation of oral mucosa and periodontium to physics, the apex locator was invented whichnow is been used frequently. The present study was conducted to evaluate the efficacy of five different apexlocators in determining the working length.
Key words: apex locator, working model
INTRODUCTIONThe ultimate success of any root canal
treatment depends on multiple factors like the
extent of caries, the biomechanical preparation, the
obturation, the remaining tooth structure, etc.
The proper instrumentation upto the apical
constriction or also called as the cemento-dentinal
junction (9) as seen earlier is also one of the vital
factor for a good prognosis. The cemento-dentinal
junction is a histological landmark and in clinical
practice it is impossible to locate it. Therefore the
apical constriction can be regarded as a clinical
landmark on which we can depend upon. The
apical constriction, when present, is the narrowest
part of the root canal with the smallest diameter of
blood supply and preparation to this point results
in a small wound site and optimal healing
conditions (18).
The traditional methods used till today rely
on the apical tug back for the termination of any
root canal instrumentation. Though this method is
effective, it can also be deceptive as the tug back
could also be possible because of any secondary
curvatures present before the apical constriction.
Also in some cases the canal may be sclerosed or
the constriction has been destroyed by
inflammatory resorption (19).
The radiographs are definitely supportive for
the instrumentation upto the apical constriction,
but they can also prove deceptive due to improper
angulation of the cone. Also, the image obtained
is a two-dimensional image of a three dimensional
object.
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The moisture on the absorbent point method
can also give us false positive results as the draining
above the apical constriction can happen.
Keeping all the above limitations in mind, an
electronic device for the determination of working
length was investigated first in 1918 by Custer et
al. His ideas were later revisited by Suzuki in 1942
(21) and Sunada in 1962 (20) for the invention of
the modern electronic apex locator apex.
The first electronic working length device
measured the working length by calculating the
electrical resistance between the periodontium and
oral mucosa that gave a constant reading of 6 k¿.
Later on many new devices were invented
measuring the frequency, impedance and
capacitance.
The present study was conducted to evaluate
the efficacy of five different apex locators in
determining the working length.
MATERIALS AND METHODS1. Preparation of samples -
Twenty freshly extracted single rooted single
canal human teeth were chosen for the study. The
teeth were stored in sodium hypochlorite for 24
hours to dissolve any tissue on the root surface.
The teeth were then scaled with an ultrasonic scaler
(EMS, Mectron) to remove any hard tissue if present
on the root surface. Proper precautions were taken
while scaling the apical part of all teeth.
An access to the root canal of all teeth was
prepared using a round and cylindrical bur (Mani
Inc.). A 15# K-file (Mani Inc.) was used to negotiate
the canal using sodium hypochlorite and normal
saline.
2. Measurement of actual working length –A 15# K-file (Mani Inc.) was introduced inside
the canal until it became visible at the apical
foramen. The silicone stop was adjusted, the file
was removed and the distance between the base
of silicone stop and file tip was measured using a
vernier caliper. To obtain the actual working length,
0.5 mm was subtracted from this measured length
(1).
3. Working model for electronic workinglength determination –
Two plastic rectangular boxes, 18 cm×3
cm×4 cm in dimension were used for preparing
this model. Alginate was poured in each of this
boxes that acted as an electroconductive medium
(7, 10, 11, 17, 22).
Ten teeth among the selected samples were
mounted vertically upto the cementoenamel
junction. All measurements were made within 2
hours of the model being prepared (15).
4. Electronic working length measurement -Five apex locators were chosen for this study,
Dentaport ZX (Fig. 1; J. Morita Corporation, Japan),
Root ZX (Fig. 2; J. Morita Corporation, Japan),
Raypex 5 (Fig. 3; Roydent Dental Products, Johnson
City, TN), Propex (Fig. 4; Dentsply), and E Magic
Finder (Fig. 5; Densiti). Each tooth among the
twenty samples was subjected to electronic
working length measurement using all five apex
locators. The entire technique was performed and
the measurements were recorded by a single
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operator. Care was taken to see that all the circuits,
batteries and the operating modes of all five apex
locators are fully functional.
At first, canals were irrigated using 5.25%
sodium hypochlorite placed with a syringe, then
the pulp chamber was gently dried with an air
syringe; cotton pellets were used to dry the tooth
surface and eliminate excess irrigating solution.
A 15# K-file with the file clip of the apex
locator to be used, was attached to the file and
inserted inside the canal until the apex locator
showed the “apex” reading. The file was slightly
pulled out until the apex locator showed the “0.5
mm” reading. The silicone stop was adjusted and
the file was removed and the distance between the
base of silicone stop and file tip was measured using
a vernier caliper.
Measurements were considered as valid if they
were stable for at least 5 seconds otherwise the
value was recorded as an unstable measurement
due to inability of the EALs to reveal a constant
reading. The recorded values were tabulated. The
actual length readings were compared to electronic
working length readings.
Statistical analysis of the recorded readings
was done using a Sign test for nonparametric
evaluation of the groups. Statistical readings were
considered significant when p < 0.05.
RESULTS
TABLE 1
TOOTH ACTUAL PROPEX ROOT DENTAPORT E MAGIC RAYPEX 5SAMPLE LENGTH ZX ZX FINDER
1 21 21 20.5 20.5 21 21
2 24 23.5 24 23 23.5 24
3 22 21.5 21.5 23 22 22
4 23 23 23 24 23 23.5
5 22 21.5 22 22 22 22
6 21 20.5 21 20.5 20.5 20.5
7 21.5 21 22 22 21.5 21.5
8 23.5 23 23 23.5 23.5 23.5
9 19 19 19 18.5 19 18.5
10 24 23.5 23.5 23.5 24 23.5
The results obtained were tabulated as follows -
*Length in mm
NIRANJAN A. VATKAR, SUCHETA SATHE, VIVEK HEGDE
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TABLE 1
TOOTH ACTUAL PROPEX ROOT DENTAPORT E MAGIC RAYPEX 5SAMPLE LENGTH ZX ZX FINDER
11 19.5 19 19 19 19 19.5
12 19.5 19 19 19 19.5 19
13 24.5 23.5 24.5 24.5 24.5 24
14 20.5 20 20 20 20 20
15 21 21 21 20.5 21 20.5
16 20 20 20 20 19.5 20
17 21 21 21 20.5 21 20
18 21 21 21.5 21 21 21
19 22 22 22 21.5 22 22
20 24.5 24.5 24 24 24.5 24
*Length in mm
Accuracy was calculated only on stable
measurements. There was a highly significant
difference (p < 0.05) when the differences between
measurements obtained with the Dentaport ZX,
Raypex 5 and Propex and those obtained with the
actual length readings were compared. The
graphical representation of each apex locator
compared with the actual length readings were are
shown below.
Table 1 and 2 shows that most measurements
were within ±0.5 mm of the actual length. One
tooth each with Propex (tooth sample 13) and
Raypex 5 (tooth sample 17) and three teeth with
Dentaport ZX (tooth samples 2, 3, 4) gave readings
that were beyond ±0.5 mm.
The statistical data was obtained as below. The
dots above the line indicate the samples that the
apex locator measured short of the apex. The dots
IN VITRO EVALUATION OF THE EFFICACY OF FIVE APEX LOCATORS
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40
below the line indicate the sample that the apex
locator measured beyond the apex. The dots on
the line indicate the samples that the apex locator
measured exactly at apex. The ‘p’ value of each
group is also indicated in each of the graph that
was calculated statistically.
DISCUSSIONThe use of electronic devices to determine
working length has gained increasing popularity
in recent years. Modern apex locators are able to
determine an area between the minor and major
apical foramina by measuring the impedance
between the file tip and the canal with different
frequencies and enables tooth length
measurements in the presence of electrical
conductive media in the root canals (12).
As the mean foramen to apical constriction
distance is approximately 0.5–1.0 mm for all teeth
types (4, 8, 13), it was chosen in this study to record
the actual working length by subtracting 0.5 mm
from the measurement when the file appeared at
the foramen.
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Some authors have suggested that taking the
instruments slightly long when using EALs and then
retracting them may increase the accuracy of
readings of EALs (5, 14). Thus, to confirm the
measurement, the file was advanced upto the apex
reading and then retracted to obtain the consistent
‘0.5 mm’ reading.
All measurements were made within 2 hours
of the model being prepared in order to ensure the
alginate was kept sufficiently humid [12].
The relative stiffness of the alginate mould
prevented fluid movement inside the canal that is
responsible of premature electronic readings
registered with previous models (2, 3, 6).
APEX LOCATOR ‘P’ VALUE
Root ZX 1.109
E Magic Finder 0.063
Dentaport ZX 0.035
Raypex 5 0.021
Propex 0.001
The results of the present study confirmed that
Root ZX and E Magic Finder can accurately
determine the canal length within ±0.5 mm from
the apical constriction. The measurements obtained
revealed that the EALs were able to measure the
canal length with a precision compared with the
actual length. If the estimated working length, i.e.
actual length ± 0.5 mm is considered to be
clinically acceptable, then the measurements made
with the Root ZX and E Magic Finder were
acceptable in virtually all cases.
One tooth with Propex and one with Raypex
5 and three teeth with Dentaport ZX gave readings
exceeding the apical constriction (0.5 mm) (Table
1 and 2).
CONCLUSIONAll these modern apex locators gave
comparable results in comparison to actual working
length. However Root ZX and E Magic Finder were
the most precise, followed by Dentaport ZX,
Raypex 5 and Propex.
In conclusion, the modern newly advanced
apex locators are gaining popularity because of
their predictability, precision and ease of working.
It helps you to know the apical constriction which
you cannot see. These gadgets have definitely
improved the quality of endodontics. This short
study was performed to confirm the accuracy of
five apex locators.
References1. Kaufman A. Y., Keila S. & Yoshpe M. Accuracy of a newapex locator: an in vitro study. International EndodonticJournal 2002 35:186–192.
2. Czerw RJ, Fulkerson MS, Donnelly JC. An in vitro test of asimplified model to demonstrate the operation of electronicroot-canal measuring devices. Journal of Endodontics 199420:605–6.
3. Czerw RJ, Fulkerson MS, Donnelly JC, Walmann JO. Invitro evaluation of the accuracy of several electronic apexlocators. Journal of Endodontics 1995 21:572–5.
4. Dummer PMH, McGinn JH, Rees DG. The position andtopography of the apical canal constriction and apicalforamen. International Endodontic Journal 1984 17:192–8.
5. Dunlap CA, Remeikis NA, BeGole EA, RauschenbergerCR. An in vivo evaluation of an electronic apex locator thatuses the ratio method in vital and necrotic canals. Journal ofEndodontics 1998 24:48–50.
6. Fouad AF, Reid LC. Effect of using electronic apex locatorson selected endodontic treatment parameters. Journal ofEndodontics 2000 26:364–7.
7. Fuss Z, Assoline LS, Kaufman AY. Determination of rootperforations by electronic apex locators. Oral surgery, Oralmedicine, Oral Pathology and Endodontics 1996 82:324–329.
IN VITRO EVALUATION OF THE EFFICACY OF FIVE APEX LOCATORS
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8. Green D. Stereomicroscopic study of 700 root apices ofmaxillary and mandibular posterior teeth. Oral Surgery, OralMedicine and Oral Pathology and Endodontics 1960 13:728–33.
9. Grove CJ The value of the dentinocemental junction inpulp canal surgery. Journal of Dental Research 1931 11:466–8.
10. Kaufman AY. Katz. Reliability of Root ZX apex locatortested by an invitro model. Journal of Endodontics 199319:201.
11. Keila S, Linn H, Katz A Kaufman AY. Morphometricanalysis of working length determined by impedance typeapex locators. Journal of Endodontics 1994 20:196 (Abstract).
12. Kobayashi C. Electronic canal length measurement. OralSurgery, Oral Medicine, Oral Pathology, Oral Radiology andEndodontics 1995 79:226–31.
13. Kuttler Y. Microscopic investigation of root apices. Journalof the American Dental Association 1955 50:544–52.
14. Lee SJ, Nam KC, Kim YJ, Kim DW. Clinical accuracy of anew apex locator with an automatic compensation circuit.Journal of Endodontics 2002 28:706–9.
15. Lucena-Mart³n C, Robles-Gijon V, Ferrer-Luque CM,Navajas- Rodr³guez de Mondelo JM. In vitro evaluation of
the accuracy of three electronic apex locators. Journal ofEndodontics 2004 30:231–3.
16. Nekoofar M. H., Ghandi M. M., Hayes S. J. & Dummer P.M. H. The fundamental operating principles of electronic rootcanal length measurement devices: review. InternationalEndodontic Journal 2006 39:595–609.
17. Neguyen HQ, Kaufman AY, Komorowski R, Friedman S.Electronic length measurement using small and large files inenlarged canals. International Endodontic Journal 199629:359–364.
18. Ricucci D, Langeland K. Apical limit of root canalinstrumentation and obturation, Part II: A histological study.International Endodontic Journal 1998 31:394–409.
19. Stock C. Endodontics-position of the apical seal. BritishDental Journal 1994 176:329.
20. Sunada I. New method for measuring the length of theroot canal. Journal of Dental Research 1962 41:375–87.
21. Suzuki K. Experimental study on iontophoresis. JapaneseJournal of Stomatology 1942 16:411–29.
22. Tinaz AC, Maden M, Aydin C, Turkoz E. The accuracy ofthree different electronic root canal measuring devices: an invitro evaluation. Journal of Oral Science 2002a 44:91–5.
NIRANJAN A. VATKAR, SUCHETA SATHE, VIVEK HEGDE
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A Three-Dimensional Evaluation of Density andHomogeneity of Root Canal Obturation with Guttaflow®
using Backfilling Technique in Comparison withConventional Lateral Compaction Technique using SpiralComputed Tomography - An In Vitro Study
P. SENTHIL KUMAR *A. R. VIVEKANANDA PAI **KUNDABALA M. ***
* Specialist Resident, ** Professor, ** Professor & Head, Department of Conservative Dentistry & Endodontics, Manipal college of Dental Sciences, Mangalore.
ABSTRACTThe objective of the study was to three dimensionally compare the density and homogeneity of “GuttaFlow®”using backfilling technique with conventional lateral compaction technique using spiral computed tomography.
30 human extracted maxillary central incisors were used for this study. Following access cavity preparation,working length was determined and root canal preparation was carried out using standard step-back technique.Root canal irrigation was performed using 2.5% NaOCl ,saline and final flushing with 17%EDTA and normalsaline.
After root canal preparation, the specimens were randomly divided into 3 groups with 10 teeth in each group.Specimens in Group-I were obturated with GuttaFlow® using backfilling technique, Group-II were obturated bylateral compaction technique using GuttaFlow® as the sealer and Group-III were obturated by lateral compactiontechnique using zinc-oxide and eugenol as the sealer.
The specimens were then analyzed in both horizontal and vertical sections from the apex to the cemento-enameljunction of each specimen with section thickness of 1mm each using Spiral Computed Tomography.
The data obtained was statistically analyzed using one way ANOVA test followed by FISHER’S test and TUKEYSHSD test.
Results showed that specimens of Group -I was denser, more homogenous compared to other groups and wasstatistically significant. In the evaluation of obturation in the apical, middle and coronal third individually, Group-I showed better results than other groups in apical and middle third which was statistically significant, butshowed inferior results in the coronal third though it was not statistically significant. And Group-II and Group-IIIshowed inferior results in the middle third when compared with Group-I and was statistically significant.
From the results of the study it can be concluded that, Obturation done using GuttaFlow® with backfilling techniqueis superior in the apical and middle third but is inferior in the coronal third of the root canal system whencompared to lateral compaction technique.
Spiral computed tomography is a very useful tool fo checking the density of obturation in endodontics.
Key words: Gutta-Flow, Spiral Computed Tomography, Obturation density, Homogeneity.
ENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGY
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INTRODUCTIONThe success of endodontic treatment depends
on the complete obturation of the complex root
canal system with an inert material1. To seal this
system, the obturating material must adapt to all
the portions of the root canal2. The Washington
study of endodontic success and failures indicates
that nearly 60% of the failure is apparently caused
by incomplete obturation of the radicular space3.
Several materials and techniques have been
developed for achieving a successful obturation,
Gutta-percha is the most commonly used root canal
obturation material and its physical properties have
made it possible to use it in several different
techniques4.
One of the most recent techniques which uses
cold flowable filling system for obturation of the
root canal system is “GuttaFlow®” which is
combination of sealer and gutta percha powder. It
consists of polydimethylsiloxane matrix highly
filled with finely ground gutta-percha. Several
studies have shown that GuttaFlow® offers excellent
flow and satisfactory physical properties5 according
to ISO standards6.Unlike thermoplasticized gutta-
percha which shows shrinkage on cooling,
GuttaFlow® expands slightly by 0.2% on setting
further enhancing its sealing properties.
Computed Tomography and Micro Computed
Tomography are currently the leading technologies
for endodontic research7. With spiral computed
tomography three dimensional volume analyses are
possible without sectioning the specimen and thus
avoiding the loss of material during sectioning8 and
it is possible to reconstruct overlapping structures
at arbitrary intervals and thus the ability to resolve
small objects is increased 9.
The purpose of the study is to analyze the
three-dimensional sealing ability of cold flowable
gutta percha (GuttaFlow®) and compare it with cold
lateral compaction technique using spiral
computed tomography.
MATERIALS AND METHODSMechanical Preparation of the Teeth
Thirty freshly extracted single rooted human
teeth with type I root canal anatomy were stored
in normal saline. Following access cavity
preparation, working length was determined and
root canal preparation was carried out using
standard step-back technique. Root canal irrigation
was performed using 2ml of 2.5% NaOCl and
normal saline and final flushing using 17%EDTA
and normal saline. The apical portion of the canal
was enlarged to a maximum of size 50. Any tooth
requiring a size larger than #50 file was discarded.
The coronal third of each canal was flared using a
#2 and #3 Gates Glidden drills.
Obturation TechniquesAfter drying the canals with paper points, the
teeth were randomly selected and divided into
three experimental groups of 10 teeth each.
TABLE. 1Experimental Groups
Groups Obturation Number oftechnique teeth
I Obturation using Gutta Flow®
(back filling technique) 10
II Obturation using using 2%ISOgutta percha points and GuttaFlow® as sealer ( lateralcompaction technique) 10
III Obturation using 2% ISO guttapercha points and zinc oxideeugenol sealer.( lateralcompaction technique ) 10
P. SENTHIL KUMAR, A. R. VIVEKANANDA PAI, KUNDABALA M.
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Analysis of the experimental specimens using
Spiral Computed Tomography.
All the experimental specimens were mounted
on a wax block and placed on the couch of the
computed tomography machine. It was moved
longitudinally towards the gantry at the pitch of
“1”and exposure with 120kv and 180mA was done
for one second.
Both vertical and horizontal sections of 1mm
thickness were made which was followed by three
dimensional reconstruction of the sections. The
specimens were further analyzed for variations in
density in 1 to 5mm from apex ( SUBGROUP I), 6to 10mm from the apex(Subgroup-II) and 11 to16mm from the apex (Subgroup-III) individually in
both vertical and horizontal sections.
The specimens were analyzed using Windows
Advantage Work Station software for
Density of the filling material.
Homogeneity and adaptation
to the canal wall.
Voids.
The analysis of all the specimens was done
followed by statistical analysis.
OBSERVATION AND RESULTSThe assessment was done using spiral
computed tomography for variation in the density
TABLE. 2Sub-Groups
SUB-GROUP -I 1 to 5 mm from the apex
SUB-GROUP II 6 to 10 mm from apex
SUB-GROUP III 11 to 16 mm from apex
RESULTSThe Density was measured in HOUNSEFIELDUNITS
TABLE. 3
and homogeneity. The values were recorded in
both horizontal and vertical sections. The results
were tabulated and graphically analyzed.
All the experimental groups were compared
statistically using ONE WAY ANOVA test and the
sub groups were compared using TUKEYS HSD
test.
In all the groups (p>0.05) was considered
statistically significant.
TABLE. 4
TABLE. 5
Analysis of density among experimentalgroups in vertical section
Analysis of density among sub-groups in vertical section
Analysis of density among experimental groups inHorizontal section
A THREE-DIMENSIONAL EVALUATION OF DENSITY AND HOMOGENEITY OF ROOT CANAL OBTURATION WITH GUTTAFLOW® USING BACKFILLING TECHNIQUE INCOMPARISON WITH CONVENTIONAL LATERAL COMPACTION TECHNIQUE USING SPIRAL COMPUTED TOMOGRAPHY - AN IN VITRO STUDY
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TABLE. 6
DISCUSSIONAchieving a complete seal of the root canal
system is of greatest importance in endodontic
therapy, The Washington study has concluded that
nearly 60% of all endodontic failure is due to
incomplete obturation of the root canal10.
The voids and crevices in the obturating mass
can interconnect with each other opening up either
apically or coronally. Further the tissue fluids,
proteins and bacteria can seep into these empty
spaces which act as a reservoir of irritants leading
to failure of endodontic treatment.
In the present study was used GuttaFlow® as
an obturating material. The ingredients include
gutta-percha powder, polydimethylsiloxane matrix,
silicone oil, paraffin oil, platinum catalyst,
zirconium dioxide, nano -silver(preservative) and
coloring agents.GuttaFlow® is obtained by adding
nano silver particles to its initial version Roekoseal
( Coltene / Whaledent) .
The material is cold flowable and sets within
10 minutes. It is supposed to be easily applied using
lentulo spirals or application syringes. The material
flows into the smallest dentinal tubules, because
of the small particle size (< 0.9microns). The
manufacturer claims a better seal and good
adaptation because of increased flowablity and the
fact that material expands slightly by 0.2% on
setting11.
Since GuttaFlow® is a cold flowable material,
there is no need for rise in the temperature of the
material like thermo plasticized materials and as
per manufacturers instructions there is no need for
compaction of the material during obturation and
hence there is no disadvantages like shrinkage on
cooling, vertical fractures due to undue forces and
is relatively easy to use compared to other systems.
However it should be noted that GuttaFlow®
belongs to the category of root canal filling pastes,
which has a high risk of void formation,over filling
or under filling. There fore this material
(GuttaFlow®) was chosen to study the flowablity,
density, homogeneity.
Spiral computed tomography was chosen over
other diagnostic aids for analysis of the specimens
because of its various advantages like Three-
Dimensional volume measurements are possible
without sectioning the specimens and thus avoiding
the loss of material during sectioning8 and three-
dimensional reconstructions9.
Here we chose 30 freshly extracted maxillary
central incisors and divided into three groups with
10 teeth each. This allowed adequate statistical
analysis and comparison with earlier studies. the
canals of all the groups were prepared using a step
back technique such that a continuously tapering
funnel shape from the apical third to the coronal
third was obtained. This facilitated for the ease of
obturation with the two techniques in the study.
In this study alternating solutions of NaOCl
and normal saline were used for canal irrigation.
Analysis of density among sub-groups inHorizontal section
P. SENTHIL KUMAR, A. R. VIVEKANANDA PAI, KUNDABALA M.
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The canals were finally irrigated with 17% EDTA
and normal saline to facilitate removal of dentin
debris and smear layer from the root canal12.
The specimens were then mounted on a wax
block and subjected for analysis using Spiral
Computed Tomography. Each section was
analyzed for variations in the density in the
obturation in Hounsefield Units (HU), and for voids
if any.
It was observed that the Hounsefield units
increase from the apex to the cemento- enamel
junction in vertical sections. This could be
attributed to the increase in the obturation mass
from the apex to the CEJ. Similarly there was a
decrease in the Hounsefield units from the centre
towards the periphery in horizontal sections. This
could be due to due to the decrease in the
obturation mass towards the periphery. These
findings were observed in all the samples. However
there were no voids in any of the specimens.
According to the result of the present study,
Group - I showed the best results among the
experimental groups with denser and more
homogeneous obturation in both vertical and
horizontal sections which was statistically
significant. This can be attributed to Highly filled
homogeneous matrix, good flow, 0.2% expansion
on setting ,ability to penetrate into the dentinal
tubules due to small particle size of the fillers and
apart from fluid and injectable nature of
GuttaFlow®, use of a master cone could also be the
reason for the denser obturation. This finding is
supported by studies done earlier by MarthaG 13
and Taranu R 14.
Group-II and Group-III showed inferior results
than Group-I which was statistically very highly
significant in the horizontal section and statistically
significant in the vertical section.
This could be attributed to the studies done
earlier by Torabinajed15 and others reported that
“a pattern of voids was frequently noticed in the
case of lateral compaction where the fillings
adapted reasonably well at the apical and coronal
parts and showed longitudinal voids in the mid
root section, thus confirming earlier findings by
Goldman and associates and Schilder16 noted that
with lateral compaction at no time a homogenous
mass is developed. The final filling consists of a
large number of separate gutta-percha cones tightly
compressed together and joined by frictional grip
and cementing substance only.
The results showed that among the subgroup-
III, Group-I showed inferior results than Group-IIand Group-III but was statistically insignificant.
This could be due to the reason that vertical
condensation using a cold plugger in the coronal
third was not done to the specimens in Group-I as
per manufacturer’s instructions,and the possible
reason for Group-II and Group-III to give better
results might be due to the vertical compaction of
the gutta-percha using a cold plugger following
lateral compaction.
The present study was done in vitro on teeth
with straight canals, further in vivo studies are
required to find its applicability in curved and
narrow canals before accepting this material for
routine obturation procedure.
CONCLUSIONFrom the results of the study it can be
concluded that
A THREE-DIMENSIONAL EVALUATION OF DENSITY AND HOMOGENEITY OF ROOT CANAL OBTURATION WITH GUTTAFLOW® USING BACKFILLING TECHNIQUE INCOMPARISON WITH CONVENTIONAL LATERAL COMPACTION TECHNIQUE USING SPIRAL COMPUTED TOMOGRAPHY - AN IN VITRO STUDY
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1. Obturation done using GuttaFlow® with
backfilling technique is better than lateral
compaction technique.
2. Obturation done using GuttaFlow® with
backfilling technique is superior in the apical and
middle third of the root canal system but is inferior
in the coronal third.
3. Lateral compaction is better in the coronal
third of the root canal, and is inferior in the middle
third compared to GuttaFlow® with backfilling
technique
4. GuttaFlow® when used as sealer is
comparable to zinc-oxide eugenol sealer.
GRAPH - I
GRAPH - II
GRAPH - III
GRAPH - IV
FIGURE 1 - Spiral computed tomography machine used foranalysis of the specimens
Comparison of mean density (HU) Vertical section
Comparison of mean density (HU) Horizontal section
Comparison of mean density (HU) Vertical section– Sub group wise
Comparison of mean density (HU) Horizontal section– Sub group wise
P. SENTHIL KUMAR, A. R. VIVEKANANDA PAI, KUNDABALA M.ENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGY
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FIGURE 2 - Image showing horizontal sections of the speci-mens
FIGURE 3 - Image showing vertical sections of the specimens.
FIGURE .4 - Section showing maximum value in Group-I.
FIGURE 5 - Section showing minimum value in Group-I.
REFERENCES:1. Cohen S, Burns CR. Pathways Of The Pulp, 6th Edition,Mosby, St Louis , Missouri, Page 219.
2. Dow PR, Ingle JI. Isotopes Determination of Root CanalFailure. Oral Surgery 1955:8:1100-4.
3. Ingle JI. Endodontics, 4th Edition, Philadelphia, PA, U.S.A.,Lea & Febiger, Page 25.
4. Brayton SM, Davis SR, Goldman M. Gutta-Percha RootCanal Fillings. Oral Surgery 1973; 35:226-31.
5. Rizzo F, Nocca G. In Vitro Evaluation of a NewExperimental Endodontic Sealer. The 33rd Annual Meeting ofthe AADR, 2004; March 10-13, Honolulu, USA.
6. Eldeniz AU, Orstavik D. Physical Properties of NewlyDeveloped Root Canal Sealers. International EndodonticJournal 2005; 38: 928.
7. Uyanik OM. Comparative Evaluation Of Three Nickel-Titanium Instrumentation Systems In Human Teeth UsingComputed Tomography. Journal Of Endodontics 2006;32:668-70.
8. Nandini S, Kandhaswamy D. Removal Efficiency OfCalcium Hydroxide Intra Canal Medicament With TwoCalcium Chelators: Volumetric Analysis Using Spiral CT - AnIn Vitro Study. Journal of Endodontics 2006; 32: 1097-1100.
9. Gopikrishna V, Bhargavi N. Endodontic Management ofMaxillary First Molar with a Single Root and Single CanalDiagnosed With the Aid of Spiral CT: A Case Report. Journalof Endodontics 2006; 32:687-90.
10. Ingle JI. Endodontics, 4th Edition, Philadelphia, PA, USA.Lea& Febiger, 1994; Page 228.
A THREE-DIMENSIONAL EVALUATION OF DENSITY AND HOMOGENEITY OF ROOT CANAL OBTURATION WITH GUTTAFLOW® USING BACKFILLING TECHNIQUE INCOMPARISON WITH CONVENTIONAL LATERAL COMPACTION TECHNIQUE USING SPIRAL COMPUTED TOMOGRAPHY - AN IN VITRO STUDYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGY
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11. Elayoti A, Achleitthner C. Homogeneity and Adaptationof a New Gutta-Percha Paste to Root Canal Walls. Journal ofEndodontics 2005; 31:687-89.
12. Pashley D. Smear Layer; Physiological Considerations.Operative Dentistry Supplement 3, 1984; 13-29.
13. Martha Brackett G. Comparision of Seal After ObturationTechniques Using a Polydimethylsiloxane Based Root CanalSealer. Journal of Endodontics 2006; 32:1188-1190.
14. Taranu R, Wegerer U. Leakage Analysis of Three ModernRoot Filling Materials after 90 Days of Storage. InternationalEndodontic Journal 2005;38:928.
15. Torabinajed M, Skobe Z. Scanning Electron MicroscopicStudy of Root Canal Obturation Using ThermoplasticizedGutta-Percha. Journal of Endodontics 1978;245-50.
16. Schilder H. Filling Root Canals in Three Dimensions.Dental Clinics of North America 1967; 11:723-44
P. SENTHIL KUMAR, A. R. VIVEKANANDA PAI, KUNDABALA M.
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Comparative Evaluation of Radiopacity of Three RootCanal Sealers Using Conventional and Digital RadiographicTechnique: An Invitro Study
* PG Student, * * Prof. and Head, Dept. Of Conservative Dentistry and Endodontics, D. A.P. M.R.V. Dental College and Hospital, Bangalore
SWETHA H.B. *SHASHIKALA K. **
INTRODUCTION:Root canal obturation is a critical determinant
of the success or failure of the endodontic
treatment, as it directly affects the outcome of the
endodontic therapy. Majority of endodontic failures
have been caused by incomplete sealing of the root
canal. Obtaining a hermetic seal in root canal is
extremely difficult. However, with the use of root
canal sealers along with well adapted gutta-percha
gives a clinician a better chance to reach this goal.1
Many different root canal sealers are currently
being used in combination with gutta-percha to
fill the root canal after biomechanical preparation.
From many years, gutta-percha has been used as a
core material with zinc oxide eugenol based
sealer.2 However zinc oxide based sealers shrink
upon setting and disintegrate over a period of time
and there by compromises the quality and the life
ABSTRACT:To compare and evaluate the radiopacity of three different root canal sealers using conventional and digitalradiographic technique.
The sealers tested were AH Plus, Endoflas and Pulpdent, by conventional and digital radiographic methods. Thesealers were mixed and placed in a stainless steel ring moulds. Aluminium step wedge was placed along side ofspecimen for the measurement of radiopacity of sealers. Radiographic films were used for conventional methodand the images were obtained after the films were developed from x-ray developing solutions. For digitalradiographic technique the images were obtained from radiovisiograph. The images obtained from both thetechniques were directly transferred to the analytical imaging software to determine the radiopacity of sealersusing grey-pixel values.
All tested materials showed radiopacity above 3mm of aluminium recommended by ANSI / ADA Specification57. Higher mean radiopacity was observed in AH Plus followed by Endoflas and Pulpdent respectively.Conventional method showed a lower value of radiopacity compare to digital radiographic technique. The meanvalues of tested sealers were varying in both the methods.
All tested materials showed radiopacity above 3mm of aluminium recommended by ANSI / ADA Specification57. Digital radiography was better than the conventional radiographic method in evaluating the radiopacity ofroot canal sealers.
KEY WORDS - Radiopacity, Digital radiography, Root canal sealers.
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expectancy of the apical seal. Recently, a few new
endodontic sealers have been developed with
improvement in the sealing and bonding ability to
the root dentin. These improvements depend on
the incorporation of resin monomer into the sealer.3
The ideal root canal sealer of any types should
meet certain general requirements according to
International Organization of Standardization. In
ascending order of importance, they should be non-
toxic, compatible with living tissues, and exhibit
chemical, physical and radiographic properties
suitable for clinical use.4 Dental diagnosis relies
mainly on radiology. In order to identify and
distinguish a root canal filling materials from the
surrounding anatomical structures, they should be
radiopaque.The root canal filling materials should
have sufficient radiopacity to see clearly the root
canal filling to detect its presence, extent and
apparent condensation.5
Earlier, conventional periapical radiography
was the most common method used for the
evaluation of the technical quality of the obturated
canal. In the conventional radiographic method, the
radiographic images were obtained by the chemical
processing and the radiopacity was evaluated by
an optical densitometer.6 However, the digital
imaging technique is an emerging area of radiology
that offers many potential benefits over
conventional method for the evaluation of
radiopacity of root canal sealers.7 In the past, many
of the literature mainly emphasized on the
solubility, adhesion and antibacterial activity of
different root canal sealers. But there are a few
studies on radiographic properties of root canal
sealers. Hence, an attempt is made to study the
radiopacity of root canal sealers using both
conventional and digital radiographic technique.1
The aim of the present study was to compare
and evaluate the radiopacity of three different root
canal sealers (Pulpdent sealer, Endoflas sealer and
AH Plus sealer) using conventional and digital
radiographic techniques.
MATERIALS AND METHODSThree root canal sealers were evaluated in this
study: AH Plus, Pulpdent and Endoflas (Table 1).
The sample size for each method is eighteen {n=
18}. Six tests are conducted for each sealer in a
method. The sealers were mixed according to the
manufacturer’s recommendations and then
introduced immediately in to two stainless steel
ring moulds (Diameter 10mm, Height 1mm). The
application of the sealers was accomplished with
the use of a syringe to avoid the air bubbles. An
aluminum step wedge made of 1100 alloy, with a
thickness varying 1 to 12mm, in uniform steps of
1mm each was positioned along side the specimen
on a glass slide.
For the conventional method, the specimens
were placed on the radiographic film (Kodak speed
Poly soft). Dental X-ray machine operating at 70
KVp and 10mA with a focus to target distance of
30 cm (ANSI/ADA 2000) was used to take the
radiographic images (fig 1). The exposure was
standardized to 0.6 s. and the films were developed
with standard x-ray developing solutions which
were maintained at constant temperature. Where
as for digital imaging technique, the images were
taken using an RVG sensor (fig 2). The images
obtained from both the methods are transferred to
a computer for the radiopacity evaluation of
radiopacity.
SWETHA H.B., SHASHIKALA K.
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RADIOPACITY ASSESSMENTThe digital images were analyzed with the Pro
plus 4.1 analytical software system. The ‘bone
density’ tool was applied to the region of the
radiographs containing the sample. Care was taken
to analyze only those regions, which were free of
air bubbles and other anomalies. The bone density
tool produced a graph of the grey- scale value of
each pixel 0(black) to 255(white) in the analyzed
segment, were recorded. Six radiographic images
are taken for each sealer for both conventional and
digital radiographic method. The mean value was
determined and tabulated for both methods (Table
2 & 3). Data were submitted to statistical analysis
using two-way analysis of variance and post hoc
test of Bonferroni (p<0.001).
RESULTSIn both the methods, analysis of variance
showed a statistically significant difference between
the radiopacity means of the tested sealers
(p<0.001). All tested materials showed radiopacity
above 3mm of aluminium as recommended by
ANSI/ ADA Specification 57. However higher
mean radiopacity was observed in AH Plus (D-
9.15mm, C-8.92mm) followed by Endoflas(D-
6.67mm,C-5.02mm) and Pulpdent(D-5.78mm,C-
4mm) respectively (Table 4). The mean values of
tested sealers were varying in both the methods
used. Conventional method showed a lower value
of radiopacity compare to digital radiographic
technique. The difference between them was found
to be statistically significant (p<0.001).
DISCUSSIONRadiopacity is widely acknowledged as a
desirable property of all intraoral materials,
including the endodontic sealers.8 Dental diagnosis
relies mainly on radiology. In order to identify and
distinguish a root canal filling materials from the
surrounding anatomical structures, the root canal
sealers should be radiopaque. The sealer should
contribute to the radiopacity of the root filling for
visualization on radiographs and evaluation of
obturation of lateral canals and apical ramification.
According to International Organization for
Standardization, the radiopacity of root canal
sealers should be more than or equivalent to 3mm
of aluminium.9 In the past, conventional periapical
radiography was the most common method used
for the evaluation of radiopacity of root canal
sealers. In the conventional radiographic method,
the radiographic images were obtained by the
chemical processing of radiographic film, using
developing and fixation solution which is time
consuming.6 However, digital imaging technique
is an emerging area of radiology that offers many
potential benefits such as better contrast,
visualization, sharp images and it is a quick
procedure.11 Digital imaging technique offer
computer based image processing and analysis for
the radiographic evaluation. The images can be
easily stored and retrievable compare to
conventional method.10
In this present study, the root canal sealers
were compared and evaluated for radiopacity using
both conventional and digital radiographic
technique. When digital radiographic method was
compared with conventional radiographic method,
it does not need any conventional periodical
radiographic film or the radiographic chemical
processing, thus saving time and decreasing the
stages that could interfere with the radiographic
quality. In addition, digital radiographic method
gives three dimensional images compare to
COMPARATIVE EVALUATION OF RADIOPACITY OF THREE ROOT CANAL SEALERS USING CONVENTIONALAND DIGITAL RADIOGRAPHIC TECHNIQUE: AN INVITRO STUDY
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conventional method, which gives only two
dimensional images. It also reduces the operator’s
exposure to radiation and provides detailed analysis
of digital images.5
In this study, aluminium step wedge is used
to compare the radiopacity of root canal sealers. It
is well established that the radiopacity of pure
(99.5%) aluminium is very close to that of human
dentine. Aluminium step wedge is fabricated by
creating several steps of 1mm thickness in
increasing order from a single aluminium block.
In this present study, the steps were created up to
12mm thickness from a single aluminium block.
These steps have the added benefit of speeding
the measurement process.8 According to Steven et
al the aluminium is used for the step wedge because
it has a linear absorption coefficient similar to that
of the enamel, relating the similarity in the variation
of aluminium to hydroxyapetite.5
Results of the present study showed that all
tested materials showed radiopacity above 3mm
of aluminium which is recommended by ANSI/
ADA Specification 57. Conventional method
showed a lower value of radiopacity compare to
digital radiographic technique for the tested sealers.
This variation may be due to the radiographic
chemical processing which can interfere with the
final radiographic quality.5 Tagger and Katz found
that, the digital radiographic method can provides
more consistent results in evaluating the radiopacity
of root canal sealers.9
In the present study, the highest mean
radiopacity was observed in AH plus followed by
Endoflas and Pulpdent respectively. The root canal
sealers vary in their radiopacity, depending
primarily on their thickness, molecular structure,
density, atomic number and the most important
their composition.5 The radiopacifier agents
compatible with high atomic weight, determines
the radiopacity of the sealers. Endoflas and
Plupdent root canal sealer consists of Zinc oxide
and barium sulphate as radiopacifying agents.
Where as AH Plus root canal sealer has newer fillers
like zirconium oxide and iron oxide. This could
contributes to greater radiopacity of AH Plus sealer
when compared to the other sealers tested.6
CONCLUSIONSAll tested materials showed radiopacity above
3mm of aluminium recommended by ANSI/ ADA
Specification No. 57. AH Plus root canal sealer
exhibited highest radiopacity followed by
Endoflas.F.S. and Pulpdent root canal sealer in both
the techniques. However, digital radiographic
method showed more consistent results than the
TABLE 1.Materials used
Product Composition Manufacturer
AH Plus Diepoxide,Calcium tungstate, Zirconium oxide, Aerosil, Pigment,1-adamantane amine, N, N’-dibenzyl-5-oxa-nonandiamine-1,9,Diamine ,Calcium tungstate ,Zirconium oxide, Aerosil ,Silicone oil Dentsply
Endoflas Barium sulphate, zinc oxide, iodoform, eugenol, calcium hydroxide,zinc acetate Sanlor
Pulpdent Zinc oxide, calcium phosphate, barium sulphate, zinc stearate,Eugenol, Canada balsam Pulpdent Corporation
SWETHA H.B., SHASHIKALA K.
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TABLE 4Results of Bonferroni Test
Technique Sealer Mean Std Dev Min Median Max F P-value
Digital AH Plus 9.15 4.01 1.00 11.00 11.00 3.352 0.063
Endoflas 6.67 0.52 6.00 7.00 7.00
Pulpdent 5.78 0.04 6.00 6.00 6.00
Conventional AH Plus 8.92 0.20 8.50 9.00 9.00 2798.115 <0.001*
Endoflas 5.02 0.04 5.00 5.00 5.10
Pulpdent 4.00 0.00 4.00 4.00 4.00
TABLE 2Conventional Radiographic Technique
AH PLUS ENDOFLAS PULPDENT
9 mm 5 mm 4 mm
8.5 mm 5 mm 4 mm
9 mm 5 mm 4 mm
9 mm 5 mm 4 mm
9 mm 5 mm 4 mm
9 mm 5.1 mm 4 mm
TABLE 3Digital Imaging Technique
AH PLUS ENDOFLAS PULPDENT
10.9 mm 7 mm 5.8 mm
11 mm 6.9 mm 5.7 mm
11 mm 6.9 mm 5.8 mm
11 mm 7 mm 5.8 mm
10.8 mm 7 mm 5.8 mm
1 mm 7 mm 5.8 mm
conventional radiographic method in evaluating
the radiopacity of root canal sealers. Hence, the
growing acceptance of digital technology as an
alternative to conventional radiography in day to
day clinical practice reveals demands for the
development of international standards for
electronic imaging.
FIGURE 1:
Stainless steel ring mould
Aluminium step wedge
Root canal sealer
A B C
Conventional radiographic images of A. AH plus sealer B. Endoflas sealer C. Pulpdent sealer
COMPARATIVE EVALUATION OF RADIOPACITY OF THREE ROOT CANAL SEALERS USING CONVENTIONALAND DIGITAL RADIOGRAPHIC TECHNIQUE: AN INVITRO STUDY
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Digital radiographic images of A. AH plus sealer B. Endoflas sealer C. Pulpdent sealer
FIGURE 2:
A B C
REFERENCES:1. Gianluca Gambarini, Luca Testarelli, Giancarlo Pongione.Radiographic and rheological properties of a new endodonticsealer. Aust Endod J: 2006; 32: 31-34.
2. M.A.Verasiani, J.R.Carvalho-Jr. A comparative study ofphysicochemical properties of AH Plus and Epiphany rootcanal sealants. Int Endod J: 2006; 39: 464-471.
3. AH Plus sealer. Scientific compendium: DENTSPLY;2005:4-19.
4. M.Tanomaru-Filho, E.G.Jorge, M.Goncalves. Evaluation ofthe radiopacity of calcium hydroxide and GIC based root canalsealers. Int Endod J:2008;41:50-53.
5. Steven Gu, Brain J, Barry Lee Musikant. Radiopacity ofdental materials using digital X-ray system. Dent Mater: 2006;22: 765-770.
6. J.R.Carvalho-Jr, L.Correr-Sobrinho, M.D.Sousa-Neto.Radiopacity of root filling materials using digital radiography.Int Endod J: 2007; 40: 514-520.
7. Mario Tanomaru-Filho, Erica Gouveia Jorge. Radiopacityevaluation of new root canal filling materials by digitalizationof images. J Endod: 2007; 33: 249-251.
8. D.C.Watts, J.F.McCabe. Aluminium radiopacity standardsfor dentistry: an international survey. 1999,Dec:30
9. Michael Tagger, Alexander Katz. Radiopacity of endodonticsealers: Development of a new method for directmeasurement. J Endod: 2003; 29: 751-755.
10. J Sabbagh, J Vreven, G Leloup. Radiopacity of resin basedmaterials measured in film radiographs and storage phosphorplate (Digora). Operative Dentistry: 2004; 29: 677-684.
11. B.Guniz Baksi, Tan Firat, Bilge Hakan Sen, Necdet Erdilek.The effect of three different sealers on the radiopacity of rootfillings in simulated canals. Oral Surg Oral Med Oral PatholOral Radiol Endod: 2007; 41: 103-138.
12. M.Tagger, A.Katz. A standard for radiopacity of root end/retrograde filling materials is urgently needed. Int Endod J:2004; 37: 260-264.
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The Effect of File Sizes in the Presence of SodiumHypochlorite and Blood on the Accuracy of Root Zx ApexLocator in Enlarged Root Canals - an In Vitro Study
PALUVARY SHARATH KUMAR *VASUNDHARA SHIVANNA **
* P. G. Student, ** Professor & Head, Dept. of Conservative Dentistry and Endodontics, College of Dental Sciences, Davangere - 577004, Karnataka.
ABSTRACT:The purpose of this study is to assess the effects of file size in the presence of Sodium hypochlorite and blood onthe efficacy of Root ZX apex locator in enlarged root canals.
The study sample comprised of 40 extracted straight, single rooted human lower premolars were used. Thecrowns of the teeth were removed with a low speed diamond saw. The actual canal length was determined byintroducing size 10 K-file in the canal until the tip of the file became visible at the major apical foramen under adigital microscope at 10X magnification.
Teeth were divided randomly into two groups, Group A (6% NaOCl) and Group B (Human blood containingEDTA as anticoagulant) of 20 teeth each (n=20). All the teeth were instrumented in three different stages.
Stage I: A 40 K-file was used as MAF, Stage II: A 60K-file was used as MAF.
Stage III: A 80 K-file was used as MAF.
Each tooth of both Groups of all stages and Root ZX apex locator were subsequently connected together in theexperimental set-up. Before electronic canal measurements, the canals were irrigated with 6% NaOCl in groupA, while in group B the canals were filled with human blood containing EDTA as an anti-coagulant. Then thereadings were taken with 10 K-File to the respective MAF sizes of the respective stages. The obtained readingswere compared with the actual canal lengths and statistically analyzed using three way ANOVA and Bonferronitests.
Three way ANOVA and Bonferroni test showed that file size, stage of preparation and type of irrigant all had asignificant influence on the measurement error (P<0.0001), with all the interactions between these three factorsbeing significant.
The present study indicates that, even in fully controlled in vitro study conditions, there is some inconsistency inthe EAL measurements. Because of this potential inconsistency, EALs should not be used to replace the routineradiographic confirmation of the canal length in endodontic therapy.
Keywords: Agar, blood, electronic apex locator, file size, root length determination, root canal preparation,sodium hypochlorite solution.
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INTRODUCTIONDetermination of working length is the first
important step in root canal debridement. It is
imperative that root canal debridement procedure
be confined to the canal in order to prevent
irritation of the periapical tissues and possible
overextension of the root canal filling (Ingle et al.
1994).2
Many reports show a mean apex-to-apical
foramen distance of around 0.5-1 mm8. However,
this site can be misinterpreted on a two dimensional
film. In cases where the apical foramen is eccentric
to the root apex ie., exit deviates bucco-lingually14,
or superimposition of normal anatomical features
and pathological changes on apical tooth, such as
impacted teeth, tori, the zygomatic arch, excessive
bone density, overlapping roots, or shallow palatal
vaults.
In 1942 Suzuki reported a device that
measured the electrical resistance between the
periodontal ligament and the oral mucosa and
registered a consistent value of approximately 6.5
k&!3.
First generation models which work on
electrical resistance were considered not accurate
in the presence of conductive fluids in the canal.
Consequently, one manufac-turer placed plastic
insulation over the electronic probe to prevent
electrical conductance through moist canal
contents. However, the thickness of the insulating
material prevented entry of the probe into tight and
tortuous canals, especially at midroot and the apical
level5.
The recently developed Root ZX (J. Morita Co)
electronic apex locator which works on the ratio
method can ac-curately measure the canal length
even under electro conductive conditions23. The
ratio method simultaneously measures the
impedances of the canal using two different
frequency (400 Hz and 8 Hz) currents and
calculates the quotient of the impedances11.
Usually for electronic canal measurements
with EALs requires the file size to be comparable
to the diameter of the canal. But the manufacturer
claims that the canal measurements with Root ZX
can be done with a much smaller file compared to
the diameter of the root canal2.
So in this study we check the effect of file sizes
in the presence of sodium hypochlorite and blood
on the accuracy of Root ZX apex locator in enlarged
root canals (In Vitro Study).
MATERIALS AND METHODSA total of 40 extracted, straight, single-rooted
human lower premolars with complete root
formation and stored in distilled water containing
10% formalin were used. Dental digital X-ray
images were taken in both buccolingual and
mesiodistal directions to evaluate the root canal
anatomy. The crowns of the teeth were removed
with a low speed diamond saw to standardize the
root length to 14.5mm and to allow access to the
root canal and establish a level surface to serve as
a stable and unequivocal reference for all
measurements. The actual canal length was
determined by introducing a size 10 K-file in the
canal until the tip of the file became visible at the
major apical foramen under a digital microscope
at x10 magnification. A rubber stop was then
carefully adjusted to the reference level and the
distance between the rubber stop and the file tip
was measured and recorded. Gates Glidden drills
VASUNDHARA SHIVANNA, PALUVARY SHARATH KUMAR
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(size 1-4, Mani, Tochigi, Japan) were then used to
prepare the coronal portion of the canal, while the
middle and apical portions of the canal were
prepared using size 10 K-files with six per cent
NaOCl for irrigation.
Experimental set up:
(a) K File. (b) Self cure acrylic. (c) Lid. (d) Polystyrene specimenbottle. (e) Tooth. (f) 1% agar which simulates as artificialperiodontium.
Each tooth was fixed to the lid of a polystyrene
specimen bottle with self-curing resin. A stainless
steel rod is screwed into the body of the specimen
bottle, was used as a neutral electrode. The
specimen bottles were then filled with one per cent
concentration of heated agar. The caps were
immediately placed over specimen bottles and the
model assemblies were refrigerated for two hours
to allow the agar to set. Each tooth and Root ZX is
connected together and used to take readings.
The teeth were divided into 2 groups (Group
A and Group B) depending upon the contaminants
used in the canals ie, 6% NaOCl and human blood
containing EDTA as anticoagulant.
The canal preparation of both Group A and
Group B teeth were done in three stages.
In stage I, a size 40 K-file was used as the
master apical file (MAF) and it was confirmed that
the larger size (>40 K-file) did not reach the apex.
The apical portion of the canal was then
instrumented using the step-back sequence by
decreasing the working length of larger files by
0.5mm. The canal was irrigated with 2ml NaOCl
using an endodontic syringe with a 27 gauge needle
in an up-down motion.
In stage II, the teeth were removed from the
specimen bottles and the canals were instrumented
in same manner and enlarged using a size 60 K-
file as the MAF.
In stage III, the teeth were removed again from
the specimen bottles and the canals were
instrumented in same manner and enlarged using
a size 80 K-file as the MAF.
All the teeth in each stage are connected to
the Root ZX as shown in experimental set up and
readings were taken with 10 K-file to MAF size of
the respective stage. The electronic measurement
was taken three times for each file and the average
value was calculated.
For each average reading, the error in
measurement was calculated as the absolute
difference between the electronically measured
canal lengths and the actual canal lengths. Three-
way ANOVA was conducted to investigate the
influence of file size, stage of preparation and the
type of irrigant on the measurement error. Multiple
comparisons were performed with Bonferroni test.
To compensate for the influence of differences in
the actual canal lengths on the measurement errors,
the actual canal length was set as a covariant in
the statistical analysis.
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RESULTSTable 1 & 2 shows the mean and standard
deviation of length and initial canal length
measurements obtained before canal enlargement
for both groups A and B. Three-way ANOVA and
Bonferroni test showed that the file size, stage of
preparation and type of irrigant had a significant
influence on the measurement error (P< 0.000l)
with all the interactions between these factors being
significant (P<0.0001). At stage 3, the
measurement error showed the largest absolute
difference in group B (1.11mm) when a size 10 K-
file was used. At all stages in both groups A and B,
the measurement error was less than 0.03mm when
the MAF were used.
DISCUSSIONMethods for the canal length determination
are either the manual or the radiographic
approaches for the precise localization of apical
narrowing. The manual technique obviously
depends on the sensitivity of the operator, whereas
in the radiologic approach, the calculation of the
working length is made with respect to the position
of the radiographic apex which not only does not
coincide with apical narrowing or even with the
apical foramen, but also depends on the series of
factors: tooth inclination, film position, length of
the beam cone, vertical and horizontal cone
angulation, and so forth. Nevertheless, the main
inconvenience is that both approaches are entirely
subjective and therefore scantly reproducible16.
Using radiography followed by subsequent
tooth extraction and sectioning, Stein and Corcoran
found that the radiographically established working
length did not actually coincide with the true apical
vertex. Electronic apex locators (EAL) have been
used clinically for more than 40 years as an aid to
determine the file position in the canal. These
devices when attached to a file are able to detect
the point at which the file leaves the tooth and
enters the periodontium. EALs obviate this problem
because their readings are not related to the apical
vertex but rather to the apical foramen.1
Early EALs were based upon the work of
Suzuki and Sunada. They relied on the principle
that the electrical resistance between the oral
mucosa membrane and the periodontium remained
constant ie, 6.5 k&!, regardless of the age of the
patient and type and shape of the tooth.3 These
devices allowed measurement of the canal length
by comparing the electrical resistance that was built
into the apex locator with the resistance between
the tip of the file and that of the periodontal
membrane.11
McDonald notes that resistance type EALs
should be operated in a reasonably dry canal or
may be used with RC Prep. NaOCl or saline
irrigants, being ionic solutions, are electrical
conductors that could cause false readings. When
using ionic irrigants and the resistance type EALs,
additional time must be taken to dry the canals
before taking as electronic measurement.9
A frequency dependent apex locator has
recently been introduced. Two electric frequencies
are normally used and the impedance difference
between the two frequencies reaches its maximum
at the apical constriction of the root canal. A
modification of this device is the Root ZX apparatus.
It is based on the principle that the ratio of electrical
impedance between two frequencies is nearly
equal when the tip of the file approaches the apical
constriction and expresses this quotient in terms
VASUNDHARA SHIVANNA, PALUVARY SHARATH KUMAR
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of the position of the electrode (file) inside the
canal. This quotient is hardly affected by the type
of electrolyte in the canal.8
The Root ZX needs no calibration. The
microprocessor of the device corrects the
calculated quotient so that the position of the tip
and the meter reading are directly related. This
occurrence means that root canal enlargement can
easily be performed while the length of the root
canal is simultaneously monitored.23
However, it has been proven that the
pathological changes in the pulp lead to changes
in the concentration of ions. Consequently, its
electrophysiological characteristics are changed,
which affects the accuracy of EALs. These changes
can be recorded by physical parameters, such as
measurement of the electronic potential of pulp,
electric conduction, or analysis of cations. Thus it
is possible to say that biological changes, effect on
the EAL measurements.15
In the present study, the apical portion of the
canal was enlarged and the apical constriction was
destroyed, although the conical shape of the canal
was still maintained. Group A showed statistically
significant better scores than Group B. In the
presence of NaOCl, the Root ZX was accurate and
the length measurements obtained with small and
large size files were comparable. The results of
Group A confirmed those of Nguyen et al., who
found that the Root ZX was accurate even when
the file was much smaller than the diameter of the
canal.
Many studies have used a ±0.5mm error
range to assess the accuracy of the EALs.
Measurements obtained with this tolerance are
considered highly accurate. Other studies rely on
a more lax clinical range of ±1.0mm to the
foremen. One reason cited for accepting a
±1.0mm margin of error is the wide range seen in
the shape of the apical zone. The results obtained
in Group B with the smaller size files may not be
clinically acceptable because the measurement
error showed the largest absolute difference value
(1.11mm) when a size 10 K-file was used. And it is
recommended that the use of files with sizes
comparable with the root canal diameter, claiming
that this would result in more accurate readings.
The results showed that file size, stage of
preparation and the type of irrigant all had a
significant influence on the measurement errors
(P<0.0001) with all the interactions between these
three factors being significant (P<0.0001). In Stage
III, the measurement error showed the largest
absolute difference in both Groups A (0.19mm) and
B (1.11mm) when a size 10 K-File was used. At all
stages in both Groups A and B, the measurement
error were less than 0.03mm when the MAFs were
used.
The present study and previous studies appear
to indicate that, even in fully controlled in vitro
study conditions, there is some inconsistency in
the EAL measurements. Because of this potential
inconsistency, EALs should not be used to replace
the routine radiographic confirmation of the canal
length in endodontic therapy
CONCLUSIONAs the diameter of the root canal increased,
the measured length with the smaller size files
became shorter. This suggests that the size of the
root canal diameter should be estimated with a
snug-fitting file should be chosen for root canal
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length measurement in the presence of blood, and
possibly serum or pus. In the presence of NaOCl,
the Root ZX was highly accurate even when the
file was much smaller than the diameter of the
canal.
Table No. 1: Comparison of Stage I, II, & IIIof Group A
Group A Stage I Stage II Stage III
10 0.10 0.16 0.19
15 0.08 0.15 0.17
20 0.07 0.14 0.15
25 0.05 0.13 0.15
30 0.04 0.12 0.12
35 0.03 0.10 0.12
40 0.02 0.08 0.11
45 0.08 0.11
50 0.06 0.10
55 0.05 0.10
60 0.02 0.08
70 0.06
80 0.02
The present study, there is some inconsistency
in the EAL measurements. Because of this potential
inconsistency, EALs should not be used to replace
the routine radiographic confirmation of the canal
length in endodontic therapy. Further clinical
studies are needed to evaluate EALs.
Group B Stage I Stage II Stage III
10 0.37 0.91 1.11
15 0.30 0.78 1.05
20 0.24 0.65 1.00
25 0.16 0.50 0.91
30 0.11 0.47 0.87
35 0.07 0.38 0.75
40 0.03 0.30 0.70
45 0.20 0.65
50 0.16 0.58
55 0.10 0.45
60 0.03 0.28
70 0.22
80 0.03
Table No. 2: Comparison of Stage I, II, & IIIof Group B
VASUNDHARA SHIVANNA, PALUVARY SHARATH KUMAR
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Fig. 1. Decoronated teeth of Group AFig. 2. Decoronated teeth of Group B
Fig. 3. Group A samples embedded in Agar material Fig. 4. Group B samples embedded in Agar material
Fig. 5. ExperimentalFig. 6. Stereomicroscope
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REFERENCES:1. Ebrahim AK, Yoshika T, Kobayashi C, Suda H. AustralianDental Journal 2006;51(2):153-157
2. Nguyen HQ, Kaufman AY, Komorowski RC, Friedman S.International Endodontic Journal 1996;29:359-364
3. Anthony Meares W, Robert Steiman H. Journal ofEndodontics 2002:28(8);595-598
4. Joslyn A. Jenkins, William A.Walker, William G. Schindler,Christopher M. Floes. Journal of Endodontics 2001:27(3);209-211
5. Ounsi H F, Naaman A. International Endodontic Journal1999:32;120-123
6. Kaufman A V, Katz A Journal of Endodontics (AAE Abstractof Papers) 1993:19(4);201
7. Roland Weiger, Christoph John, Heiner Geigle, Zahnarzt,Claus Lost. Journal of Endodontics 1999:25(11);765-768
8. Vajrabhaya L, Tepmongkol P. Endod Dent Traumatol1997:13;180-2.
9. Russell J. Czerw, Michael S. Fulkerson, Jerome C. Donnelly,
and James O. Walmann. JOE 1995: 21(11); 572-575
10. Fabio Luiz D Assuncao, Diana Santana de Albuquerque,and Linalda Correia Ferreira. JOE 2006:32(6);560-562
11. Jose L. Ibarrola, brent L. Champman, James H. Howard,Kenneth I. Knowles, and Marvin O. Ludlow. JOE1999:25(9); 625-626
12. Chihiro Kobayashi, and Hideaki Suda. JOE1994:20(3);111-114.
13. Craig A. Dunlap, Nijole A. Remeikis, Ellen A. BeGole,and Cindy R. Rauschenberger. JOE 1998: 24(1); 48-50.
14. Shahrokh Shabahang, William W.Y. Goon, and Alan H.Gluskin. JOE 1996:22(11);616-618.
15. Maja Kovacevic, and Tomislav Tamarut. JOE 1998; 24(5):346-351.
16. Lucena –Martin C, Robles-Gijon, Ferrer-Luque C M, andNavajas-Rodriguez de Mondelo J M. JOE 2004;30 (4):231-233.
17. Marat Tselnik, Craig Baumgartner J, and Girdon MarshallJ. JOE 2005; 31 (7): 507-509.
VASUNDHARA SHIVANNA, PALUVARY SHARATH KUMAR
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Sealing Ability of Four Materials in the Orifice of RootCanal Systems Obturated With Gutta-Percha
ABHISHEK PAROLIA *KUNDABALA M. **SHASHI RASMI ACHARYA ***VIDYA SARASWATHI ****VASUDEV BALLAL *****MANDAKINI MOHAN ******
* Assistant Professor, ** Professor and HOD, *** Professor and HOD, **** Associate Professor, ***** Reader, ****** Assistant Professor, Dept. of Prosthodontics,Manipal College of Dental Sciences, Mangalore. Karnataka. India.
ABSTRACTFailure to maintain the coronal as well as apical seal may expose obturated canals to microbes that could retardhealing and create infection in the periodontal ligament or supporting osseous structures. 50 single rooted teeth(Type I canal anatomy) were randomly assigned to 4 experimental and 2 control groups. Ten specimens eachwere sealed with Mineral Trioxide Aggregate (MTA), Tetric Flow, Glass Ionomer Cement (GIC) and Light CureGlass Ionomer cement (LC GIC). After creation of uniform orifice diameter, the smear layer was removed and thecanal systems obturated using lateral compaction of gutta-percha (GP). GP was removed to the depth of 3.5 mm,experimental materials placed in orifice and the roots submerged in Rhodamine-B dye in vacuum for one week.Specimens were longitudinally sectioned and leakage measured using a 10X stereomicroscope and graded fordepth of leakage. According to the result of the present study LC GIC demonstrated significantly better seal(p<.01) than MTA however there was no statistically significant difference in leakage (p>.01) between TetricFlow, GIC and LC GIC and in between MTA, Tetric Flow and GIC.
Key Words: Orifice barrier, Tetric flow, GIC, LC GIC, MTA, Dye under vacuum
INTRODUCTIONCoronal microleakage can produce complete
bacterial penetration in nonsurgical root canal
treated teeth ( 1, 2). It has been reported that 59.4%
of endodontically treated teeth failed because of
lack of an adequate post endodontic restoration
(3). Loss of coronal seal may occur due to leakage
of temporary filling material or fracture of the
permanent restoration. Perhaps the use of a material
to seal the orifice, in addition to the restoration,
could mitigate this bacterial leakage if that
restoration was lost or became unserviceable. It
has been reported that root canal treated teeth
without coronal barrier had significantly more
failure rate than teeth with coronal barrier of
amalgam, composite resin, glass ionomer or
intermediate restorative material (4).Despite
research supporting the effectiveness of coronal
barriers, a universally accepted protocol that
incorporates a coronal barrier after root canal
therapy is nonexistent. Thus, the addition of another
barrier between the oral environment and the root
canal system appeared to have a positive effect in
reducing leakage and increasing possibilities for
success.
Hence the purpose of this investigation was
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to evaluate and compare the sealing ability of four
experimental materials as an intra-orifice barrier
after obturation of root canal system.
MATERIALS AND METHODS50single-rooted teeth, with Type I canal
system, stored at 100% humidity were used.
Crowns were removed at the cementoenamel
junction using diamond disc. A #10 K-file (Denstply
Maillefer, Swiss made, Ballaigues) was inserted and
advanced until it was visualized at the apical
foramen. The file was retracted 1 mm and working
length was established at this level. A ProTaper SX
file (Denstply Maillefer, Swiss made, Ballaigues)
was used to flare the orifice. 5.25% NaOCl (Vishal
Dentocare Pvt Ltd, India) and RC Prep (Medical
Products Laboratories INC) were used in between
each instrument. ProTaper SI, S2, Fl, F2, and F3
files were used sequentially per manufacturer’s
instructions in a crown down technique. A uniform
orifice diameter of 1.3 mm, at its widest point, was
made using a #5 Gates Glidden bur (MANI, INC
Japan) to a depth of 3.5mm. Once instrumentation
was completed, the canal was rinsed with two ml
of 5.25% NaOCl, followed by 2 ml of 17% EDTA
solution, and with a final rinse of chlorhexidine
0.2%w/v (ICPA Health Products LTD, India). Canals
were dried with sterile paper points and obturated
with .02 taper gutta-percha points (Denstply
Maillefer Swiss made, Ballaigues) and AH plus
sealer (Denstply DeTrey gMbH Germany) in lateral
compaction technique.
40 teeth randomly divided into four
experimental groups, with the remaining ten teeth
being divided equally between positive and
negative controls.
Group Number Experimental Intraorificeof teeth sealing material
Group I 10 Mineral TrioxideAggregate (MTA)
Group II 10 Tetric Flow
Group III 10 Glass Ionomer Cements(GIC)
Group IV 10 Light cured Glass IonomerCements (LC GIC)
+ve Control 5 Instrumented and obturatedteeth with gutta-perchaat the level of the orifice.
-ve Control 5 Instrumented and obturatedteeth with three coats ofnail polish
Heat carrier was used to remove gutta-percha
to the depth of 3.5 mm and verified the depth with
a periodontal probe. ProRoot MTA (Dentsply/tulsa
Dental Products), Tetric flow (Ivoclar Vivadent),
GIC (GC Corporation Tokyo, Japan) and LCGIC
(GC Corporation Tokyo, Japan) were placed into
the orifice as per manufacturer’s directions in
samples of respective groups. Each tooth was
placed into a coded container and allowed for
sealer and all experimental materials to set. All
these samples were kept in humidor for 48 hrs.
Three layers of nail varnish were placed on
all experimental teeth coating their root surface
from root apex to the level of the cementoenamel
junction. Positive controls were obturated, but not
coated with nail varnish. Negative controls were
obturated and completely coated with nail polish,
including the orifice. Samples were submerged in
a vacuum flask containing Rhodamine-B dye,
subjected to vacuum pressure of 75 torr for 30
minutes, and allowed to remain in the dye for seven
days (5). After exposure to the dye, samples were
rinsed with running water to remove dye from the
external surface. Nail varnish was gently removed
ABHISHEK PAROLIA, KUNDABALA M., SHASHI RASMI ACHARYA, VIDYA SARASWATHI, VASUDEV BALLAL, MANDAKINI MOHAN
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with a# 15 disposable safety scalpel .These samples
were longitudinally sectioned using diamond disc
and samples were observed and leakage was
measured to the greatest penetration using a 10X
stereomicroscope (Olympus) using micrometer
from the coronal extent of the orifice material.
Results were tabulated and data were analyzed
using ANOVA & Tukey Tests.
RESULTSPositive controls leaked at least 5 mm into the
gutta-percha, and no leakage was observed in the
negative control group. Table 1 shows mean depth
of penetration, in millimeters, for each material.
MTA has shown the maximum leakage, at 1.6
mm mean penetration while LC GIC has shown
the least, at 1.1 mm mean penetration which
showed statistically significant difference between
MTA and LC GIC. There was no statistically
significant difference in leakage (p>.01) between
Tetric Flow, GIC and LC GIC and in between MTA,
Tetric Flow and GIC.
DISCUSSIONAn efficient seal to prevent leakage in the root
canal system from both oral fluids & peri-radicular
tissues is prerequisite for the success of endodontic
treatment. Teeth obturated with gutta-percha and
sealer, in the absence of a temporary restoration,
showed leakage ranging from 70% to 85% of the
root length within 56 days, when exposed to
saliva(2).
It has also been pointed out the importance
of the temporary seal lasting even after root canal
therapy is completed, emphasizing the importance
of early final restoration of the tooth (6). Iowa group
found that endotoxin can penetrate obturating
material faster than bacteria and they also extended
the caveat: “the need for an immediate and proper
coronal restoration after root canal treatment is
therefore reinforced (7). At University of Tennessee,
the Himel group reported that “the teeth without
an intraorifice barrier leaked significantly more than
the teeth with glass Ionomer barrier (8). So the
present study is undertaken to evaluate and
compare the sealing ability of four experimental
which have been shown to have good sealing
ability with coronal as well as radicular dentin (9,
5,10).
Dye penetration method to check the
microleakage is a simple, easier and cost effective
method so we decided to use this method. This
study used Rhodamine-B dye as it has small particle
size, better penetration, water solubility,
diffusability and hard tissue non-reactivity (11).we
have used dye under vacuum penetration method,
It has been reported that vacuum helps to remove
entrapped air which can prevent complete dye
penetration (12). It has been reported that 3.5 mm
of material to be the minimum thickness required
in coronal restorations to prevent leakage so in this
study material thickness of 3.5 was taken to seal
the canal orifice (13).
The results of this study indicated that LC GIC
demonstrated a significantly better seal than MTA,
Tetric Flow and GIC. This could be due to
command setting and better adhesion with tooth
structure. Resin modified glass ionomers set by two
mechanisms: acid-base reaction common to all
glass ionomers and a photochemical
polymerization of water soluble monomers and
methacrylate groups(14).Polymerization shrinkage
still occurs in these materials due largely to resin
SEALING ABILITY OF FOUR MATERIALS IN THE ORIFICE OF ROOT CANAL SYSTEMS OBTURATED WITH GUTTA-PERCHA
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component; however immature cement continues
to take up fluid from dentin, causing the material
to expand which compensates polymerization
shrinkage(15).The adhesion of LC GIC appears to
be by development of an ion-exchange layer
adjacent to the dentin similar to conventional glass
ionomer materials(16). Moreover the shear bond
strength of LC GIC is said to be higher than
conventional GIC (17, 18). This is due to the slow
acid-base reaction in LC GIC and availability of
polyacid for a longer time So this might have
contributed for the better sealing ability.
In the present study MTA has shown
statistically significantly more leakage than LC GIC,
this could be attributed to the absence of tissue
fluid in root canal treated teeth which could
interfere in growth of hydroxyapatite crystals,
responsible for chemical bonding (19).It has also
been found that a secondary seal was required over
MTA in furcation restorations to minimize leakage
as MTA was easily discerned from dentin and easy
to remove with ultrasonics (20).
Conventional GIC and Tetric Flow have
shown more leakage than LC GIC but it is not
statistically significant. This could be due to weaker
bonding of conventional GIC (17) than LC GIC and
more polymerization shrinkage of Tetric Flow than
LC GIC (21).
So, the present study concludes that double
seal is required which could be achieved by using
an intra-orifice barrier. In this study LC GIC has
found to be superior over other experimental
materials as an intra-orifice barrier. However,
further research such as a long-term study using
other methods of microleakage detection, may
confirm better clinical results.
Materials Number Mean Std.Deviation Minimum Dye Maximum DyePenetration (mm) Penetration (mm)
MTA 10 1.6375 0.60955 0.50 2.50
Tetric flow 10 1.4250 0.38819 1.00 2.25
GIC 10 1.265 0.51603 0.50 2.10
Light cured GIC 10 1.1125 0.45505 0.50 2.00
Table1. Comparison of marginal means of depth of penetration for experimental materials
Mean PDifference
MTA Tetric flow 0.2125 0.540GIC 0.3750 0.092LC GIC 0.5250 0.008 s
Tetric flow GIC 0.1625 0.735
LC GIC 0.3125 0.207
GIC LC GIC 0.1500 0.780
P= .01s
Table 2
ABHISHEK PAROLIA, KUNDABALA M., SHASHI RASMI ACHARYA, VIDYA SARASWATHI, VASUDEV BALLAL, MANDAKINI MOHAN
68
Figure1. Mean dye penetration in respective groups(Stereomicroscope 10 X)
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MTA Tetric Flow
GIC LC GIC
REFERENCES:1. Swanson K, Madison S. An evaluation of coronalmicroleakage in endodontically treated teeth. Part I: timeperiods. J Endod 1987; 13:56-9.
2. Madison S, Swanson K, Chiles SA. An evaluation of coronalmicroleakage in endodontically treated teeth. Part ll: sealertypes. J Endod 1987; 13:109-12.
3. Vire DE. Failures of endodontically treated teeth:classification and evaluation. J Endod. 1991; 17:338-42.
4. Carman JE, Wallace JA. An invitro comparison ofmicroleakage of restorative materials in the pulp chamber ofhuman molar teeth. J Endod 1994; 20:571-75.
5. Jenkins S, Kulild J, Williams K. Sealing ability of threematerials in the orifice of root canal systems obturated withgutta-percha. J Endod 2006; 32:225-27.
6. Khayat A, Lee SJ, Torabinejad M. Human saliva penetration
of coronally unsealed root canals. J Endod 1993; 19(9):458-61.
7. Alves J, Walton R, Drake D. Coronal leakage: Endotoxinpenetration from mixed bacterial communities throughobturated post-prepared root canals.J Endod 1998; 24(9):587-91.
8. Wolcott JF, Hicks ML, Himel VT. Evaluation of pigmentedintraorifice barriers in endodotically treated teeth. J Endod1999; 25(9):589-92.
9. Barrieshi-Nusair KM, Hammad HM. Intracoronal sealingcomparision of mineral trioxide aggregate and glass Ionomer.Quint Int 2005; 36:539-45.
10. Barthel CR, Strobach A. Leakage in roots coronally sealedwith different temporary filling. J Endod 1999; 25(11):731-34.
11. Wu MK, Wesselink PR. Endodontic leakage studies
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reconsidered. Part I. Methodology, application and relevance.Int Endod J 1993; 26: 37–43.
12. Wimonchit S et al. A comparison of techniques forassessment of coronal dye leakage. J Endod 2002;28(1):1-4.
13. Webber RT , del Rio CD, Brady JM, Segall RO. Sealingquality of a temporary filling material.Oral Surg Oral MedOral pathol. 1978; 46:123-30.
14. Seiler KB. An evaluation of glass ionomer paste restorativematerial as temporary restorations in endodontics. Gen Dent2006; Jan-Feb: 33-6.
15. Wilson AD. Resin modified glass ionomer cements. Int JProsthodont 1990; 3:425-9.
16. Lin A, McIntyre NS, Davidson RD. Studies on adhesionof glass Ionomer cements on dentin. I Dent Res 1992;71:1836-41.
17. Burgess JO, Barghi N, Chan DCN, Hummert T. A
comparative study of three glass Ionomer base materials. AmJ Dent 1993; 6:137-41.
18. Kerby RE, Knobloch L. The relative shear bond strengthof visible light curing and chemical curing glass Ionomercement to composite resin. Quint Int1992; 23:641-44.
19. Sarkar NK et al. Physicochemical basis of the biologicproperties of mineral trioxide aggregate. J Endod 2005;31(2):97 – 100.
20. Hardy I, LIewehr FR, Joycc AP, Agee K, Pashley DH.Sealing ability of one-up bond and MTA with and without asecondary seal as; furcation perforation repair materials. JEndod 2004; 30:658-61.
21. Miguez PA, Pereira PN, Foxton RM, Walter R, NunesMF, Swift EJ Jr. Effects of flowable resin on bond strength andgap formation in Class I restorations. Dent Mater. 2004 Nov;20(9):839-45.
ABHISHEK PAROLIA, KUNDABALA M., SHASHI RASMI ACHARYA, VIDYA SARASWATHI, VASUDEV BALLAL, MANDAKINI MOHAN
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Current Endodontics LiteratureSowmya Shetty, Associate Professor, Department of Conservative Dentistry and Endodontics, A. J. Institute of Dental Sciences, Mangalore
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Clinical Studies of Fiber Posts: A Literature Review
Maria C. Cagidiaco, MD, DDS, PhDa/Cecillia Goracci, DDS, PhDb/Franklin Garcia-Godoy, DDS, MSc/Marco Ferrai,MD, DDS, PhDd (2008)
This literature review aimed to find answers to relevant questions regarding the clinical outcome of endonticallytreated teeth restored with fiber posts. All clinical studies published since 1990 in journals indexed in MEDLINEwere retrieved by searching PubMed with the query terms “fiber posts and clinical studies.” The reference list of thecollected articles was also screened for further relevant citations. The strength of the evidence provided by thereviewed papers was assessed according to the criteria of evidence-based dentistry. Five randomized controlledtrials (RCTs) on fiber posts have been published in peer-reviewed journals. A meta-analysis is not applicable to thesestudies since they do not address the same specific clinical question. Retrospective and prospective trials withoutcontrols are also available. Two RCTs indicate that fiber-reinforced composite posts outperform metal posts in therestoration of endontically treated teeth. However, this evidence cannot be considered as conclusive. Longer-termRCTs would be desirable. The placement of a fiber-reinforced composite post protects against failure, especiallyunder conditions of extensive coronal destruction. The most common type of failure with fiber-reinforced compositeposts is debonding.
‘Int J Prosthodont; 21:328-336’,2008
Association between Bifidobacteriaceae and the clinical severity of root caries lesions
M. Mantzourani, M. Fenlon, D.Beighton
The isolation of members of the family Bifidobacteriaceae (bifids) from oral samples has been sporadic and arecent cloning study has suggested that they are not detectable in root caries lesions.
To better understand the presence of bifids in root caries we obtained clinical samples (15 of each) from soundexposed root surfaces, leathery remineralizing root lesions, and soft active root lesions. We investigated each for thepresence of bifids using a mupirocin-containing selective medium and identified the isolates using 16S recombinantRNA sequencing.
The proportion of bifids, as a percentage of the total anaerobic count, was significantly related to the clinicalstatus of the sites sampled, being 7.88±1.93 in the infected dentine from soft lesions, 1.61 ± 0.91 in leatherylesions, and 0.05±0.39 in plaque from sound exposed root surfaces. Bifids were isolated from all soft lesions, 13 of15 leathery lesions, and five of the plaque samples. Bifidobacterium dentium was isolated from four of the plaquesamples, from 13 samples from leathery lesions, and from 12 of the 15 samples of infected dentine from the softactive lesions. Parascardovia denticolens and Scardovia genomospecies C1 were each isolated from samples associatedwith all three clinical conditions whereas Scardovia inopicata and Bifidobacterium subtile were both isolated from
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the infected dentine of the leathery and soft lesions. Bifidobacterium breve was isolated from the infected dentine ofsoft root caries lesions.
Bifids may be routinely isolated from root caries lesions using appropriate cultural methods.
‘Oral Microbiology and Immunology’, 24 (1):32-37,2008. Published Online 12 December 2008 Journal compilation© 2008 Blackwell Munksgaard Ltd.
Vascularization of Engineered Teeth
A. Nait Lechguer, S. Kuchler-Bopp, B. Hu, Y. Haikel and H. Lesot
The implantation of cultured dental cell-cell re-associations allows for the reproduction of fully formed teeth,crown morphogenesis, epithelial histogenesis, mineralized dentin and enamel deposition, and root-periodontiumdevelopment. Since vascularization is critical for organogenesis and tissue engineering, this work aimed to study (a)blood vessel formation during tooth development, (b) the fate of blood vessels in cultured teeth and re-associations,and (c) Vascularization after in vivo implantation. Ex vivo, blood vessels developed in the dental mesenchyme, fromthe cap to bell stages and in the enamel organ, shortly before ameloblast differentiation. In cultured teeth and re-associations, blood-vessel-like structures remained in the peridental mesenchyme, but never developed into dentaltissues. After implantation, both teeth and re-associations became revascularized, although later in the case of the re-associations. In implanted re-association, newly formed blood vessels originated from the host, allowing for theirsurvival, and affording conditions organ growth, mineralization, and enamel secretion.
Key Words: tooth tissue engineering · vasculatization · VEGFR · CD31
‘J Dent Res 87(12):1138-1143, 2008’
Effects of Er: YAG Laser Irradiation on Biofilm-forming Bacteria Associated with EndodonticPathogens In Vitro.
Noiri Y, Katsumoto T, Azakami H, Ebisu S (2008).
With the development of dental laser delivery systems that can enter into the root canals, it is possible to use Er:YAG lasers to remove the residual biofilm associated with infected root canals. We examined their effects againstbiofilms made of Actinomyces naeslundii, Enterococcus faecalis, Lactobacillus casei, Propionibacterium acnes,Fusobacterium nucleatum, Porphyromonas gingivalis, or Prevotella nigrescens in vitro. After Er:YAG laser irradiationwith energy densities ranging between 0.38-0.98 J/cm2, the biofilm samples on hydroxyapatite disks were quantitativelyand morphologically evaluated. The Er: YAG laser was effective against biofilms of 6 of the bacterial species examined,with the exception of those formed by L. casei. After irradiation, the numbers of viable cells in the biofilms weresignificantly decreased, whereas atrophic changes in bacterial cells and reductions in biofilm cell density were seenmorphologically. Er: YAG lasers might be suitable for clinical application as a suppressive and removal device ofbiofilms in endodontic treatments
Journal of Endodontics34 (7):826-829, 2008.
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Dental Pulp Stem Cells: A Promising Tool for Bone Regeneration
d’Aquino R, Papaccio G, Laino G, Graziano A (2008).
Human tissues are different in term of regenerative properties. Stem cells are a promising tool for tissueregeneration, due to proliferation, differentiation and plasticity. Although several loci or niches within the adulthuman body are colonized by a significant number of stem cells, access to these potential collection sites is oftenlimited. Interaction with biomaterials is important for therapeutic use of stem cells. Dental pulp stem cells (DPSCs)have shown to meet these requirements. Access to the collection site of these cells is easy and produces very lowmorbidity. Extraction of stem cells from pulp tissue is highly efficient. These cells have extensive differentiationability and the demonstrated interactivity with biomaterials makes them ideal for tissue reconstruction. SBP-DPSCsare a multipotent stem cell subpopulation of DPSCs which are able to differentiate into osteoblasts, synthesizing 3Dwoven bone tissue chips in vitro and that are capable of differentiating into osteoblasts and endotheliocytes. Severalstudies have found that these are multipotent stromal cells that can be safety cryopreserved, used with severalscaffolds, and have a long lifespan and build in vivo an adult bone with Haversian channels and an appropriatevascularization. A definitive proof of their ability to produce dentin has not been yet done. Interestingly, they seemto possess immune privileges as they can be grafted into allogenic tissues and seem to exert anti-inflammatoryabilities, like many other mesenchymal stem cells. The easy management of dental pulp stem cells makes themfeasible for use in clinical trials on human patients
Stem Cell Reviews 4(1):21-26, 2008
The Sodium Hypochlorite Accident: Experience of Diplomates of the American Board ofEndodontics
Kleier DJ, Averbach RE, Mehdipour O (2008).
To better understand the etiology associated with sodium hypochlorite accidents, the authors surveyed diplomatesof the American Board of Endodontics. Of the 314 diplomates who responded, 132 reported experiencing a sodiumhypochlorite accident. Questions asked involved those about the age and sex of the patient as well as the tooth beingtreated, preoperative signs, symptoms, diagnosis, and radiographic appearance. Data was analyzed by chi-squaretests. Significantly more women experienced sodium hypochlorite accidents compared with men (p < 0.0001).More maxillary teeth than mandibular teeth (p < 0.0001) and more posterior than anterior teeth (p < 0.0001) wereinvolved. A diagnosis of pulp necrosis with radiographic findings of periradicular radiolucency were positivelyassociated with such accidents (p < 0.0001). Most respondents reported that patient signs and symptoms completelyresolved within a month. The occurrence of an accident, by itself, did not adversely affect the endodontic prognosisof the involved tooth. Anatomic variations may contribute significantly to the occurrence of a sodium hypochloriteaccident
Journal of Endodontics 34(11):1346-1350, 2008
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The Effect of Mineral Trioxide Aggregate on the Mineralization Ability of Rat Dental Pulp Cells:An In Vitro Study.
Yasuda Y, Ogawa M, Arakawa T, Kadowaki T, Saito T (2008).
The aim of this study was to investigate the effect of mineral trioxide aggregate (MTA) on cell viability andmineralization ability of rat dental pulp cells. The pulp capping materials, such as MTA, Dycal (Dentsply Caulk,Milford, DE), and Superbond C&B (SB; Sun Medical, Shiga, Japan) were placed on transwell inserts and cultured withrat dental pulp cells. MTA and SB exhibited no cytotoxicity, whereas almost all cells had died after 72 hours ofculture with Dycal. MTA significantly stimulated mineralization by 60% compared with the control. MTA and Dycalsignificantly upregulated by two-fold the level of bone morphogenetic protein (BMP)-2 messenger RNA expressioncompared with the control. Furthermore, MTA increased BMP-2 protein production by about 40%, whereas Dycalsignificantly reduced it. Although MTA and Dycal increased the concentration of extracellular calcium by about 0.4mmol/L, SB had no effect. These results suggest that BMP-2 may play an important role in mineralization stimulatedby MTA
Journal of Endodontics 34(9):1057-1060, 2008.
Stem cells and tooth tissue engineering
Yen A, Sharpe P (2008).
The notion that teeth contain stem cells is based on the well-known repairing ability of dentin after injury.Dental stem cells have been isolated according to their anatomical locations, colony-forming ability, expression ofstem cell markers, and regeneration of pulp/dentin structures in vivo. These dental-derived stem cells are currentlyunder increasing investigation as sources for tooth regeneration and repair. Further attempts with bone marrowmesenchymal stem cells and embryonic stem cells have demonstrated the possibility of creating teeth from non-dental stem cells by imitating embryonic development mechanisms. Although, as in tissue engineering of otherorgans, many challenges remain, stem-cell-based tissue engineering of teeth could be a choice for the replacement ofmissing teeth in the future.
Cell and Tissue Research 331(1):359-372, 2008
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