Endo Instruments and Materials

BSc, BDS, BEd, MSc,MDSc

1.INTRODUCTION TO THE

ENDODONTICS

• Summary

• About root canal treatment

• Conditions treated

• Before the treatment

• During the pulpectomy

• After the pulpectomy

• Potential benefits

• Potential risks

• Alternatives and variations

• Questions for your doctor

2.INTRUMENTS AND MATERIALS

3.INSTRUMENTS

2

• Intracanal Endodontic Instruments

• Barbed Broaches, Root Canal Rasps, Root

Canal Applicators, and Root Canal

Probes

• Root Canal Files and Root Canal

Reamers

• Root Canal Filling Condensers and

spreaders

• Engine Driven Instrument

• Devices for Determining Working Length

• Devices for Controlling Working Length

4.MATERIALS

• Devices for Intracanal Irrigation

• Devices for Root Canal Filling

• Root Canal Filling Materials

• Root Canal Filling Methods

3

• Efficacy of Root Canal Fillings and Materials

• Root Canal Core Filling Materials Gutta Percha

• Silver Cones

• Root Canal Sealers and Cements

• Zinc Oxide-Eugenol Cement and Sealers

• Non-Zinc Oxide Eugenol Cements and Sealers

• Therapeutic Cements and Sealers

• Physical Properties of Root Canal Cement

and Sealers

• Tissue Toxicity Tests of Endodontic Materials

• Future Directions in Filling Materials.

5.ENDO SAFETY SYSTEM

• MEITRAC I-III

• MEIPULP TITANIUM PULP PLASTER

• MEITAN TITANIUM ROOT FILLING POST SYSTEM

4

• MEIPOST I-II TITANIUM ROOT POST SYSTEMS

• MEIPOST II, TITANIUM ROOT POST SYSTEM

• MEIPOST III, SECURIT POST SYSTEM

• MEIPOST IV TWO-IN-ONE ROOT POST SYSTEM

• HEDSTROEM FILES WITH LONG HANDLE

• ROOT CANAL REAMERS ‘GATES’ STAINLESS

• ROOT CANAL PEESO

• PULP CHAMBER BURS

5

1. Introduction to the Endodontics

Endodontics is “that branch of dentistry concerned with the

morphology, physiology, and pathology of the human dental pulp and periradicular

tissues. Its study and practice encompass the basic and clinical sciences including of

the normal pulp, the etilogy, diagnoses, prevention, and treatment of diseases and

injuries of the pulp and associated perriradicular tissues.” Endodontics deals with the

diagnosis and treatment of pulpal and periradicular diseases. It is a discipline that

includes different procedures and as such is based on two inseparable bodies; art and

science. These art and science procedure needed instruments and materials.

Definition: An endodontist is dental specialist that has completed 4 years of dental school along with an additional 2 or more years of specialty training in endodontics (root canals). In other words, an endodontist is a root canal specialist.Pronunciation: En-do-don-tistAlso Known As: Root Canal Specialist

Root Canal Treatment

Also called: Endodontic Treatment, Endodontic Therapy, Endodontic Microsurgery, Root Canal Therapy

• Summary

• About root canal treatment

• Conditions treated

• Before the treatment

• During the pulpectomy

• After the pulpectomy

• Potential benefits

6

• Potential risks

• Alternatives and variations

• Questions for your doctor

Summary

Root canal treatments are procedures designed to save teeth damaged by injury and/or severe tooth decay (cavities). The procedure may also be called root canal therapy or endodontic treatment. “Endo” means inside and “odont” means tooth in Greek. The procedure involves the removal of pulp, the soft tissue inside the tooth.

One or more root canals are found inside every tooth. Each canal contains pulp, often referred to as the nerve center of the tooth. Pulp actually consists of nerves, blood vessels and connective tissue. When that pulp is damaged by deep cavities or a fractured or cracked tooth, it can cause severe pain (toothache) and a root canal treatment may be needed.

There are multiple steps in a root canal treatment, but the basic procedure involves drilling into the top or back of the tooth, removing all or part of the pulp (pulpectomy), replacing it with a rubber-like material (such as gutta percha) and putting an artificial crown (cap) over the tooth to strengthen it. Patients may be given either a local or general anesthetic.

Root canal treatment may be performed on only one root or in more than one root in the same tooth. Depending on their type and location in the mouth, teeth can have up to four root canals per tooth.

The root canal procedure is typically performed in two or more dental appointments (each lasting 30 to 90 minutes, depending on the case). A dentist or an endodontist (a dentist trained in diagnosing and treating internal tooth disorders) can perform the procedure.

Certain alternatives to root canal treatment (e.g., pulp capping and pulpotomy) are typically used only on injured teeth. Pulling the tooth (tooth extraction) is an alternative, but dentists usually try to avoid this option. Extraction creates additional problems associated with missing teeth, including shifting or misaligned teeth, bite problems (malocclusion) and gum recession. In addition, missing teeth can dramatically alter a person’s appearance, which may be distressing.

Some people who undergo root canal treatment may need a second treatment if infection recurs in the tooth or if an infected root canal was overlooked during the initial procedure. According to the Academy of General Dentistry, root canal treatments have a 5 percent failure rate.

The American Association of Endodontists (AAE) estimates that nearly 16 million

7

root canals are performed each year in the United States. According to the American Dental Association, smokers are more likely than non-smokers to need root canal treatment.

Over the years, root canal treatments have gained a reputation for being painful. However, according to the AAE, root canal treatment today is no more painful than having a filling placed or another type of dental restoration.

About root canal treatment

A root canal treatment removes the tooth’s pulp (soft tissue at the center of the tooth that is composed of connective tissue, nerves and blood and lymph vessels). Also called root canal therapy and endodontic treatment, the procedure may be recommended to save a

tooth when the pulp is infected or injured. The procedure may be performed by a dentist or endodontist (dentists who specialize in diagnosing and treating problems inside the tooth).

Infection due to tooth decay is the most common reason for root canal treatments. Tooth injury, such as a chipped, fractured or broken tooth, may also require root canal treatment. Teeth that are sensitive to hot and cold (sensitive teeth) may need root canal treatment if other desensitizing methods fail. In

addition, repeated dental procedures (e.g., artificial crowns or fillings) on the same tooth can weaken the tooth and prompt a root canal treatment.

Pulp begins at the tip of the root, where the tooth is anchored into the jaw, and travels through the root canals, which are long, thin passageways that lead up to the pulp chamber at the center of the tooth. The chamber is an area inside the crown and below the enamel and dentin. A tooth has only one pulp chamber but may have up to four root canals leading to the chamber. Therefore, root canal treatment on a single tooth may involve removing pulp from multiple root canals that are infected or damaged.

The pulp’s primary function is to supply nourishment (blood and nutrients) for growing teeth while the nerve within the pulp sends messages to the brain, such as whether a drink or food is hot or cold. The nerve also sends pain messages when there is an injury or infection.

Removing an infected pulp does not harm the tooth but does eliminate pain caused by infection or injury by removing the central nerve tissue of the tooth.

In children’s permanent teeth, which are continuing to grow, a procedure called a pulpotomy may be attempted In this procedure, only part of the dead or infected pulp is removed, so the blood vessels can continue to nourish the tooth.

For many people, root canal treatment is preceded by severe pain (toothache). The source of that pain is typically an abscess (a pocket of pus) that can form at the tip of the

8

root when the pulp is infected.

A root canal may be necessary even if there is no pain, when x-rays or a dental examination reveal root cavities or darkened teeth (an indication of dead of dying pulp).

Root canal therapy can be used to treat both primary teeth (baby teeth) in children or permanent (adult) teeth. However, depending on the kind of injury involved with a child’s baby teeth, extraction may also be an option. When extracting baby teeth, it is important to discuss the need for space maintainers. These orthodontic appliances maintain the space of the baby tooth, so that the replacement adult tooth will be able to erupt into the mouth.Dentists try to avoid extracting teeth because doing so can create other mouth problems.

Some people who undergo root canal treatment may require repeated treatments if the initial procedure fails to completely rid the tooth and canal of bacteria and reinfection occurs. Others may require an additional procedure called an apicoectomy if infection spreads to the tip of the tooth’s root (apex). This procedure is also called endodontic microsurgery because it uses a microscope to guide the endodontist in cutting out the infected root tip.

Root canal treatment has long had a reputation as being very painful, and many patients may have chosen to forego the procedure – opting to have the problem tooth pulled instead. However, according to the American Association of Endodontists (AAE), dental techniques and anesthesia have improved in recent years and the painful root canal is largely a myth today. Patients often report the pain to be no more severe than that of a filling, according to the AAE. In many cases, the anticipation of a root canal treatment is worse than the treatment itself.

According to the AAE, nearly 16 million root canals are performed each year in the United States. Estimates are that half of U.S. adults have had root canal treatments by age 50, according to the American Dental Association (ADA). Smokers are 70 percent more likely than non-smokers to need root canal treatments, according to the ADA.

Conditions treated using root canal treatment

9

having the procedure include:

• Relieving pain (toothache) associated with pulp infection, sensitivity or damage.

• Ridding the tooth of decayed tissue that can spread to other teeth.

• Restoring a natural smile to those whose teeth have been cracked or chipped.

• Avoiding extraction. Pulling a tooth can relieve the pain associated with a toothache and infection. However, it can also open the door for other problems. They may include shifting and misaligned teeth, gum recession, bite problems (malocclusion) and social problems associated with missing teeth.

Potential risks with root canal treatment

Like all medical procedures, there can be risks associated with root canal treatment. Patients are urged to discuss the entire procedure as well as any risks or complications before, during and after each step of the treatment.

Some people report experiencing pain during the root canal treatment. This can happen when the anesthesia fails to completely numb the nerves in and around the infected tooth. Anesthesia may also be affected by toxins released from an abscess (a pocket of pus that can form on the gums or at the roots when there is severe infection). When that pus oozes onto the gums, it can make anesthesia less effective at numbing the nerves. However, dentists are often aware of the presence of an abscess prior to the procedure and can take steps to minimize its effects on the anesthesia.

Another possible risk is that the procedure will not relieve pain or fix the problem that caused the pain. According to the Academy of General Dentistry, root canal treatments have a 5 percent failure rate. When the initial root canal therapy fails, a second treatment may be necessary. This means months or sometimes years later the entire procedure is redone, including placement of the artificial crown. Possible causes of treatment failure include:

• The original treatment failed to remove all of the infected pulp tissue and decayed tooth fragments and re-infection occurs.

• The tooth contained an additional root canal that was missed during the initial treatment, such as a narrow, curved branch of the main root canal.

• The infection spread to the tip of the tooth’s root (apex) or into the alveolar bone. Another procedure called an apicoectomy may be needed to remove the root tip.

• The adhesive or cement used to seal the root canal begins to leak.

• The weakened tooth cracks or fractures.

There are also risks associated with use of anesthesia. The injection needle used to administer local anesthetics can hit a nerve and cause extended numbness and pain. General anesthesia can cause nausea and vomiting that typically wears off within 24

10

2. Instrument and Materials

The following report on endodontic instruments, devices, and materials is

not intended nor was any attempt made to include every known product and technique

in endodontics. The report was to provide representative examples of the principle

types of materials and instruments and how they are used. The selection of materials

and instruments and/or techniques discussed do not therefore cover endodontics as it

is practised in every country of the World. The Commission is desirous of a continued

review of this area and details of other materials, including compositions, and of

instrumentation is solicited so that the Commission can formulate a second report to

include reviews of techniques and products used in countries other than in the Western

Hemisphere, Northern Europe, the United Kingdom, and Japan upon which the

current report is largely based.

The technical skills required in endodontic practice invariably lead to a

high degree of personalized artistry in execution. This occurs despite the near

universal conviction that cleansing, shaping, and sealing the root canal system lies at

the heart of the clinical practice of endodontics.

Until very recently, endodontic instruments or materials have not been

investigated as either instruments or materials apart from the more generalized

concepts of treatment. Most of the instruments and materials in clinical use today

have been used with significant clinical success by the proponents of a variety of

techniques for at least fifty years. Puterbaugh (1928) in reviewing the endodontic

materials and techniques of his contemporaries would feel most comfortable with the

prevailing views of our own period.

11

One of the most persistent precepts in endodontics has been that a root canal

system left empty even in the absence of microorganisms, necrotic debris, or toxic

materials will ultimately result in periapical pathplogy. This conception of the root

canal system (“hollow tube concept”) underlies endodontic philosophy even today in

North America and much of the world. A second and equally persistent precept is that

rather than being principally a surgical and technical problem endodontic treatment is

a therapeutic problem. This conception of root canal therapy is particularly strong in

Europe but has its adherents throughout the world. The interplay of these two basic

conceptions of the root canal system and the role of therapeutic agents in endodontic

treatment underlie endodontic philosophy and account for the thinking processes

associated with the literature dealing with endodontic instrumentation and root canal

filling. Because of much additional information in recent years, we can be reasonably

certain that in the absence of tissue debris and/or microoganisms, unfilled root canals

or root canals filled with biodegradable and resorbable non-toxic materials will not of

themselves cause periapical pathology. Most of the available evidence seems to

support the contention that the least amount of tissue irritation is produced during root

canal instrumentation when the instruments are kept within the confines of the root

canal system. However, the procedure that produces the most inflammatory response

within acceptable limits apparently produces the most profound resolution of the

overall problem. This may be the cause with root canal instrumentation, provided

further insults are not added to injury by medications or filling materials with poor

biocompatibility.

Some Example of Instruments and Materials

1. Root canal reamer, file, gate gliden drill and bur.

12

2. Root canal micro motor, handpiece, and rotary files.

3. Armamentaum for root canal treatment

4. Formo Cresol

13

5. Cresolformalina

6. EndoFill

7. Endomethasone Ivory

8. G.P point (size 10,15,20,25,30,35,40,45,50,55,60,65,70,80,90,110,120,130,140 )

14

9. Silver point (10-140)10. P.Point (10.140)

3. Instruments

• Intracanal Endodontic Instruments

The principal investigations of root canal instrument designs and physical

characteristics were initiated in the 1950’s by Ralph F. Sommer, an influential

clinician and teacher, who was an ardent advocate of the use of silver cones as root

canal filling materials.6 This was predicated upon the hypothesis that the natural

anatomy of the apical constriction was conical in form and could be readily and

accurately prepared so as to provide a seat for a prefabricated silver cone to be

cemented in place, thereby sealing the root canal.

15

Problems in precisely fitting prefabricated silver cones to prepared root

canals were not infrequently encountered and several proposals to overcome these

were offered. J. I. Ingle being well inculcated in the instrumentation and root canal

filling techniques associated with silver cones, and cognizant of the problems

associated therewith, advocated standardization of the root canal armamentarium.27-29

Simultaneously a series of investigations was begun to evaluate the feasibility of

using the root canal file itself, rather than a silver cone, to seal the root canal, thus

eliminating problems with matching sizes. In order to determine whether stainless

steel root canal files, which were found to be suitable for implantation in tissue, were

comparable in physical and working characteristics to the commonly used carbon

steel files, the properties of root canal files needed to be determined. This was done

by J. F. Bucher and followed up by M. A. Heuer with an in-depth analysis of the

physical and structural characteristics of root canal files and reamers in 1959 in which

the standardized instruments advocated by Ingle and his co-workers were included.

These investigations and those of R. G. Craig and F. A. Peyton and others which

followed that the first in which root canal instruments were studied as entities apart

from their use in clinical situations. Pressure was brought to bear on manufacturers of

root canals instruments for closer instrument tolerances quality control, and

standardization of products.

Oliet and Sorin at the University of Pennsylvania, while not concerned with

the accuracy of the preparation, investigated the efficiency of root canal files and

reamers in preparing simulated root canals. Although proponents of Gutta Percha root

canal filling techniques in which accurate preparations of the root canal were not an

essential characteristic decried attempts to standardize instruments and materials

progress in this regard contined. Proponents of rigid core root canal filling techniques

16

were hard pressed to substantiate the underlying hypothesis of their approach with

several authors reporting studies that either lent support to, or detracted from, the

premise that accurate geometrical preparations of the root canal system are possible.

The relationships of the instrumentation technique to the root canal filling procedure

remains controversial to this day. Standardization has come to mean standardization

of the root canal instruments and/or materials them selves and not the root canal

preparation or root canal filling. In a search for simpler and efficient methods of root

canal instrumentation engine driven instruments have been reintroduce and new

studies to objectively evaluate their potential are being reported. A dichotomy of

opinion regarding root canal instrumentation persists in the semantics of endodontics

where proponents of instrumentation systems that lead to geometrical root canal

shapes suitable for rigid core root canal filling techniques speak in terms of root canal

preparation whereas proponents of a point of view that does not accept the feasibility

of transforming a naturally occurring root canal anatomy into a predetermined

geometrical form speak in terms of root canal cleansing and shaping.

The instruments used in endodontics can be grouped into three categories

according to use. This has been done by the International Organization for

Standardization and Federation Dentaire Internationale through its Joint Working

Group on Root Canal Instruments. These groups are:

Group 1.

Instruments used in the root canal, hand use only: Included are root

canal files type K(Kerr) and Type H(Hedstrom), root canal reamers type K(Kerr), root

canal rasps Type R(Rattail files), root canal barbed broaches, root canal probes

(smooth broaches) root canals applicators, root canal filling condensers (pluggers) and

root canal filling spreaders.

17

Group 2.

Instruments used in the root canal, engine driven two parts. (Shaft

and operative head made as two pieces.) Included are instruments having shafts

designed for use in either a straight handpiece, contra angle handpiece, or in specially

designed endodontic contra angle handpiece only. The operative head is either

identical with the root canal files, reamers, rasps or barbed broaches of Group 1 or

specially designed instruments such as root canal reamers B-2, root canal “quarter

turn” reamers, or root canal paste carries (Lentulo).

Group 3.

Instruments used in the root canal, engine driven, one part. (Shaft

and operative head made as one piece.) Included are root canal reamers type B-1,

Type G (Gates-Glidden), type P(Peaso), type A, type D, type O, type KO, type T, and

type M, as well as at the root facer.

The Joint Working Group on Root Canal Instruments adopted this

classification and terminology for root canal instruments in 1973 for presentation to

the International Organization for Standardization member body countries (including

the United States) and the Federation Dentaire International Commission on Dental

Materials, Instruments, Equipment, and Therapeutics.

• Barbed Broaches, Root Canal Rasps, Root Canal

Applicators, and Root Canal Probes

18

Root Canal Rasps Type R, root canal broaches, root canal

applicators, and root canal probes are historically the oldest forms of root canal

instruments dating into the nineteenth century. The root canal probe is a light, slender,

flexible, smooth or edged metal hand instruments usually pointed and tapered used for

exploring root canals. Probes are usually made of soft iron wire. Rasps, broaches, and

applicators are manufactures from soft iron wires by the placement of a series of

incisions along the shaft and the subsequent elevation of the edge of the incision to

create a cutting prominence, barb, or a roughened surface. The depth and angle of cut

in the shaft is the principal determinant of the instrument type.

Root canal broaches are thin, flexible, usually tapered, and pointed metal

hand instruments with sharp projections curving backward and obliquely. The

incisive cuts of the manufacturing tool are extrusive and near parallel to the soft

iron shaft. Consequently, the projections produced are a series of sharp pointed

barbs along the operative head of the instrument. The identification symbol for

root canal broaches is an eight-pointed star.

Barbed broaches are used primarily for the removal of intact pulp

tissue. The instrument is introduced slowly into the root canal until gentle contact

with the root canal walls are made; then the instrument is rotated 360o in either a

clockwise or a counter clockwise manner to entangle the pulpal tissue in

protruding barbs. The instrument is then withdrawn directly from the root canal. If

successful, the majority of the pulp comes with it. Because of the design of the

barbed broach, the use of this instrument is limited in clinical practice. It is

being increasingly used to retrieve a paper point or cotton dressing inadvertently

lodged in a root canal and is most effective when used for this purpose. Because

of its soft wire core the barbed broach is a very flexible instrument and can be

19

readily broken if not used with caution. The incisions in the core, which form the

barbs, when elevated extend for some distance into the metal and increase the

potential for instrument fracture. If the instrument is forced deeply into a tapering,

narrow root canal the tips of the barbs are compressed against the instrument shaft

giving a false sense of security. However, when the deeply embedded broach is

withdrawn the barbs engage the surrounding tooth structure and the more force

used to withdraw the instrument the deeper they dig into the predentinal surfaces.

If enough force is applied the barbs will either (1) bend back on themselves

allowing the instrument to be withdrawn (rare), (2) fracture off in the walls of the

root canal (not uncommon), or (3) tear at the base of the incisions that produced

them resulting in a fracture of the instrument itself (the most likely occurrence). A

fine tactile sense is necessary when using barbed broaches to avoid the

aforementioned problems, therefore the use of heavy handled “broach holders” is

not recommended. Rather, barbed broaches without handles or with light short

handles are to be preferred.

Barbed broaches have been used in engine driven contra angles

designed for endodontics without significant incidences of instrument fracture.

They were selected for use in the Giromatic types of rotary reciprocal

handpieces primarily because of their flexibility. Investigations have revealed that

they are ineffective as root canal cleansing instruments when used in endodontic

contra angles because the rotary action of the instrument compresses the barbs

against the core of the instrument and burnishes them in place after a very few

minutes at the 1000 to 1800 RPM normally used. In effect the barbed broach

becomes a smooth root canal probe in a short time and exerts little if any

cleansing action, but does lose some of its tendency to fracture.

20

Root canal rasps type R are hand operated, tapered and pointed instruments

on which the cutting prominences are distinct points. The incisive cuts of the

manufacturing tool are shallow and near perpendicular to the soft iron shaft.

Therefore, the cutting prominences produced are a series of ovoid or semicircular

elevations along the operative head of the instrument. Rasps are used to enlarge

the root canal by abrasive action on the dentinal surfaces. Although the term rattail

file has been applied to this instrument, such nomenclature is considered

undesirable. This identification symbol selected for root canal rasps type R is

an eight-point polyhedron.

Root canal rasps type R being similar in design to barbed broaches but

with shallower and more round protrusions have also been used in engine driven

contra angles designed for endodontics with results slightly better than broaches

as far as cleansing effectiveness is concerned.71 As might be anticipated by their

design they produce rough walled preparations in comparison to the other types of

root canal instruments. For purpose of rasping or honing a root canal they have

been superseded by files type H (Hedstrom) in most techniques.

Root canal applicators are light, slender, tapering, flexible pointed

instruments, circular in cross-section with the working head roughed to aid in

holding cotton fibres and/or liquids for application into root canals. Root canal

applicators and root canal probes are seldom used in routine endodontic practice.

If it is necessary to swab a root canal by means of cotton fibres on a metal

instrument a fine barbed broach can easily and readily fulfil the need of an

applicator. In place of root canal probes, once used extensively for the exploration

of a root canal prior to instrumentation, the smallest sized root canal files type K

are the usual instrument of choice in modern practices.

21

• Root Canal Files and Root Canal Reamers

Root canal files and reamers are the most frequently used root

canal instruments in current endodontic practices. The principal instruments are

the root canal files type either K or H, for former being the more common. Root

canal reamers of type K are more limited in their use and usefulness. Root canal

files types K are more limited in their use and usefulness.

Root canal files type K and root canal reamers type K were developed by

the Kerr Manufacturing Company shortly after the turn of the century to meet the

need for more effective cutting instruments for use in root canals. They are

manufactured from carbon steel or stainless steel wire onto which is machined

either a three or a four-sided tapered pyramidal blank. The blank portion is then

twisted to introduce a series of spirals into what will become the operating head of

the instrument.

A blank twisted so as to produce from less than a quarter to less than a

tenth of a spiral per millimetre of length, dependent upon size, produces an

instrument having from 0.80 to 0.28 cutting flutes per millimetre of operating

head and this is designated as a reamer. A blank twisted so as to produce from one

quarter to over a half of a spiral per millimetre of length, dependent upon size,

produces an instrument having from 1.97 to 0.88 cutting flutes per millimetre of

operating head and this is designated as a file. Although the essential difference

between files and reamers of type K is the number of spirals or cutting flutes per

unit of length the tendency, particularly in wire sizes larger than 0.30 millimetres

in diameter, is for files to be twisted from blanks which are square in cross-

sectional shape and reamers from blanks which are triangular in cross-sectional

22

shape and reamers from blanks which are triangular in cross-sectional shape.

Most, if not all, type K instruments are twisted from blanks which are square in

cross-sectional shape in wire sizes smaller than 0.30 millimetres in diameter.

Thus, files are generally, but not necessarily, manufactured from blanks which are

square in cross-sectional shape throughout their range of sizes, whereas this is not

true for reamers. The relationship of cross-sectional shape to instrument

identification is responsible for much confusion in the empirical literature of these

types of root canal instruments. The selection of blank shape is a manufacturing

prerogative and varies from company to company for both files and reamers.

Root canal reamers type K are either hand or power operated, usually

tapered and pointed, metal instruments with loose spiral cutting edges, sometimes

serrated, used to enlarge root canals by a rotary cutting action. The identification

symbol selected for root canal reamers type K is an equilateral triangle.

Root canal files type K are hand operated, tapered and pointed, metal

instruments with tight spiral cutting edges, which are so arranged that cutting

occurs on both a push or pull stroke. A root canal file is used to enlarge the root

canal by either rotary cutting or abrasive action. The identification symbol

selected for root canal files type K is a square.

More is known about root canal files and reamers of type K than

any of the other types of instruments used in endodontics due not only to their

widespread acceptance but also to the impetus placed on instrument investigation

by the development of national and international standards. Root canal

instruments of the K type are size for size stiffer and stronger than comparable

types of instruments. This is due in large part to their mode of manufacture

wherein the grain structure of the wire blank is preserved and the entire bulk of

23

metal in the working portion of the instrument makes up the blade with its cutting

edges. The ductility of the instrument, whether of carbon or stainless steel varies

according to the work hardening induced during drawing and fabrication. Work

hardening is a function of size, shape, and tightness of twist. For a given amount

of twist the larger instrument, assuming the same shape, will be more work

hardened due to greater strains at its outer surfaces and edges. Similarly, a square-

shafted instrument with greater bulk at its outer extremities will have more work

hardening than a triangular shaped instrument or the tighter the twist the more

work hardening will be induced. A reamer has about one-half the number of twists

of a file of the same size and therefore has about half the work hardening. A sixty

file is three times larger than a twenty file, has approximately three-quarters the

number of twists, and is subjected to about two and one half times more work

hardening. Stainless steel is more ductile than carbon steel but this accounts for

little differences as far as reamers are concerned, being more significant for

clinical purposes in files.

The shape of the shaft of the instrument can be of importance in clinical

practice. The triangular shaft requires a one-third rotation of the instrument to

complete a cutting circle of the root canal wall whereas the square shaft requires

but a quarter turn to accomplish the same end. An instrument having a triangular

shaft gives a deeper cut with thicker cutting chips than does an instrument having

a square shaft due to smaller contact angle with the root canal wall.

In either instance when the blade engages the root canal wall a large

amount of compression distortion occurs on the dentin resulting in cracks growing

as tangents of the orbit of movement of the instrument edge. When the cracks

extend to a certain distance a chip of the surface will break away from 0.005 to

24

0.01 millimetres in depth and from 1 to 4 millimetres in length.48 Whether using a

file or reamer of type K the net result is the same if a cutting circle is completed.39

Because of differences in bulk, instrument ductility, and contact angle with the

root canal wall between a square shafted file and a triangular shafted file the

differences in the clinical feel of the instrument and its consequences can be

significant. If the clinician is not aware of this change of instrument shaft shape,

he is likely to experience an increase in instrument breakage by assuming a

natural increasing progression of applied forces in his instrumentation.

It has been demonstrated that only by the rotary action of a root canal file

or reamer of type K can a root canal preparation that is round in cross section be

made. In relatively straight root canals this can be accomplished 80% of the time

at the apical one millimetre level. In severe canal, curvatures this can be

accomplished approximately one-third of the time at the same level. Neither files

nor reamers of type K when used with a reaming action, will produce any

significant deviation from circular canal preparations, but files when used with

rasping actions do produce significant deviation from circular preparations. Aside

from being slightly more flexible and less susceptible to fracture, reamers of type

K offer no advantages over files of type K.

Too deep a bite of the cutting edge of a root canal file or reamer of

type K into the root canal wall during rotary movement of the instrument can

lock the instrument into the tooth. If continued torque is applied in a clockwise

cutting motion the spirals will first elongate then twist upon themselves as the

elastic limit of the metal is passed. Root canal instruments with uneven spacing of

the spirals of flutes of their working blades have been subjected to these forces

and are liable to fracture. If detected they should be discarded. Two types of

25

fractures of type K instruments have been observed. The first is a splintering of the

instrument as continued clockwise torque is applied and the second is a sudden

clean break of the instrument usually seen when counter clockwise torque is

applied to a locked instrument. American Dental Association Specification No.28

specifies the minimum values for torque. It is important to note that these are

values for clockwise fracture and are significantly higher than those for counter

clockwise fracture.

Root canal files type K have not found favour for use as engine

driven instruments as they are generally too stiff to negotiate all but the finest

canals. Reamers of type K are available for use in contra angles or straight

handpieces but have not been adopted for endodontic contra angles. The fracture

potential and hazards of root canal perforation due to their stiffness are very real

dangers when used in rotary engine driven handpieces. To overcome the lack of

flexibility found in the usual K types a “quarter turn” reamer has been developed

for use with endodontic contra angles. This instrument lacks the spiralling and

resulting strain hardness of the K types and closely resembles the blank from

which they are fabricated. No reports of the effectiveness of this instrument are

obtainable yet.

Root canal files type H, Hedstrom files, are made by machine grinding the

flutes of the file into the metal stock of the operating head of the instrument so as

to form a series of successively larger intersecting cones from the tip toward the

handle. The root canal files type H are hand or power operated, tapered and

pointed, metal instruments with spiral cutting edges, which are so arranged that

cutting occurs on a pull stroke only. A root canal file type H is used to enlarge the

26

root canal by either cutting or abrasive action. The identification symbol for root

canal files type H is a circle.

The root canal file type H, more commonly known as the Hedstrom file, is

frequently used in endodontic practice when the necessity for flaring of the root

canal from the apical region to the occlusal or incisal orifice exists or the root

canal anatomy does not lend itself to the rotation and pull action usually

associated with the use of files of the K type. The design of the type H file is such

that the bulk of metal in the working blade that supports the cutting surfaces does

not extend to the edges of the instrument but occurs as a central core of metal.

This relationship between the overall size of the instrument and its inherent

strength and flexibility can be deceptive as the instrument is only as strong or as

flexible as the central core of metal from which the cutting edges protrude. When

placed in contact with a root canal wall the cutting edges contact the wall at angles

approaching 90o and, when the instrument is with drawn, exert an extremely

effective honing action.

To use root canal files for maximal effectiveness Shoji recommends the

type K for preparation of the circular apical retention from and type H for the

cleansing and shaping of the continue. No engine driven instruments have been

demonstrated to be as effective as these hand operated K and H files.

H files have been used in endodontic contra angles where it was thought

that their flexibility and design would be well suited. But as they cut only upon

withdrawal they proved to be ineffective when rotary forces of a reciprocating

nature were applied. Rapid vertical strokes only proved their deceptive

vulnerability to fracture without realization of their full potential when forced into

narrow canals. Nygaard-Qstby has recommended modification of the basic type H

27

file by blunting or removal of the sharp tip of the instrument and this has some

merit when used in an appropriate manner.

• Root Canal Filling Condensers and spreaders

Root canal filling condensers and root canal filling spreaders generally

have long handles of stainless steel or chromium plated brass much as similar

instruments used in operative dentistry although short handled condensers and

spreaders similar to designs used for root canal instruments have bee introduced

recent years (Luks) principally as “finger pluggers”. Root canal filling condensers

can either be of a uniangular or bayonet style. Generally, root canal spreaders are

of the bayonet style

Root canal filling condensers (pluggers) are smooth, flat-ended, slightly

tapered metal instruments used to condense filling material, primarily apically, in

a root canal. Root canal filling spreaders are smooth, pointed and tapered, metal

instruments used to condense filling material, primarily laterally, in a root canal.

• Engine Driven Instrument

Although historically engine driven root canal instruments have not been

extensively advocated in the United States, due principally to the hazards of root

perforation or instrument breakage associated with their usage, a number of types

have been developed. Introduction of the Giromatic and Racer engine driven

contra angle handpieces specifically designed for endodontic usage has rekindled

interest in engine driven root canal instrumentation.

28

The Giromatic operates by rotary reciprocal action of the instrument

through a 90o arc whereas the action of the Racer is by vertical oscillation of the

instrument as well within the root canal. Root canal instruments adaptable to

reduced speed contra angles which operate in the usual 360o rotary fashion are also

available.

Two instruments especially designed for engine operation are the root

canal reamer type B-2 and the “quarter turn” reamer. Both instruments belong to

Group II as the shaft and operating head of the instruments are made as two

pieces. The root canal reamer type B-2 has a cylindrical working head with two

cutting edges forming a spiral. Its cross-sectional shape is a rectangle. The

working head and shank are similar to the more familiar reamers type K. The root

canal “quarter turn” reamers are power-operated, tapered and pointed metal

instruments for use in special endodontic handpieces. The instrument is similar in

shape to the blank of a file type K prior to the twisting procedure used to produce

cutting flutes. The root canal paste carrier (Lentulo) is a power operated small

spiral instrument used in conveying filling material or medicaments into the root

canal. A wide variety of engine driven root canal instruments is made where the

shaft and operative head are one pieces similar to the design of dental burs. All of

these Group III root canal instruments are termed reamers with the exception of

the root facer.

The various single part engine driven root canal instruments of Group III

are primarily used in the cervical portion or orifice of a root canal as they are not

well adapted to use in the deeper mid and apical portions of the root canal proper.

All these including the root facer have special purposes for which they were

designed. The principal ones seen in American endodontic practices are the

29

reamer type G, commonly known as the Gates-Glidden drill, and the reamer type

P, commonly known as the Peaso reamer. Both these instruments have a long

history in endodontics but currently are enjoying a revival as they are

recommended by some clinicians for finishing and enlarging the orifice and

cervical third of a root canal following serial filling and flaring with root canal

files. The use of either of these instruments to enlarge an uninstrumented root

canal or prepare the root for a post core retainer is fraught with dangers of

perforation. Preferably the canal, whether it contains pulpal debris or root canal

filling material, should be enlarged with hand instruments and the engine driven

reamers of Group III should be considered as auxiliary instruments to alter the

shape of the preparation only. In many instances long tapered diamond stones can

be used in this manner with little if any danger of removing excessive tooth

structure or perforating the root.

The mechanical principle of reciprocating rotary motion and its application

to the use of endodontic instruments has been known for many years. Ingle refers

to it as “Vaiven” which he interprets from the Spanish as a “rolling-rotating

motion” and advocates its use in pathfinding. The endodontic contra angles

produce this action mechanically. In addition, the Racer type also moves the

instrument vertically with a short push-pull action. Aware of the dangers of

pushing debris beyond the confines of the root canal by the injudicious use of

apically directed strokes of root canal instruments, most practitioners have been

cautious in adopting the Racer instrument. Claims for operating efficiency are

often made for engine driven instruments as compared to the time consuming use

of hand operated root canal instruments but in at least one study comparing the

use of the Giromatic with broaches to hand operated type H files in forty-one

30

canals no significant differences in the operating time could be found. Neither

have claims of lessened incidences of instrument breakage been substantiated by

comparative investigations, particularly when the ineffectiveness of the

instruments used in the endodontic contra angles is considered. Use of the

endodontic contra angle for root canal exploration has advantages as the ability of

root canal instruments to penetrate curved and fine canals when placed in a

Giromatic is surprising to even its most fanatic detractors. This is due no doubt in

large part to the sustained mechanical application of “vaiven” motion. This ease of

root canal negotiation coupled with significant losses of tactile sensation create

the principal hazards of the device which are inadvertent penetration of the apical

foramen and/or lack of accurate control over the working length of the instrument.

Endodontic contra angles are not without merit if problems of instrument and

contra angle size, properly designated instruments, and methods of accurate length

control can be overcome.

Specification Scope and Requirements.

In 1962 at the annual session of the American Association of

Endodontists, the Research Committee of the Association met with several

representatives of the manufacturers and/or suppliers of root canal instruments to

discuss standardization of the endodontic armamentarium. Out of these

discussions was formed a working committee on endodontic instruments and

materials under the auspices of the North American Section of the International

Association for Dental Research with F.A. Peyton as its chairman. In 1964, this

group consolidated its efforts with those of the National Bureau of Standards, the

National Institute of Dental Research, and the American Dental Association. The

31

following year the American Association of Endodontists adopted the terminology

and nomenclature of the proposed standardized instrument systems as the

officially recognized system of the association. In response to numerous

developments in the standardization of dental materials and devices on a

worldwide basis the responsibility for standards development were transferred to

the American National Standards Institute (ANSI) and its Committee Z-156

(Dentistry) later to be designated Committee MD (Medical Devices) -156 with the

Council on Dental Materials and Devices of the American Dental Association

acting as the secretariat. Under the joint auspices of the Federation Dentaire

Internationale and the International Organization for Standardization, whose

membership consists of numerous national standards institutes, the development

of worldwide standards for endodontics instruments proceeds under TC (Technical

Committee) -106 JWG (Joint Working Group) -1 and its task groups (now Task

Group 9 of ISO/TC 106/WG4) on terminology, dimensions and measuring

system, and physical properties and quality control. The Seventh Draft of the

Proposed Specification for Root Canal Files and Reamers was accepted by ANSI

Committee MD-156 for distribution, commentary, and preliminary test evaluating

prior to adoption as the American National Standard in March 1973 and was

adopted by the Council on Dental Materials and Devices as American Dental

Association Specification Number 28 in December 1975.

American Dental Association Specification No. 28 is for root canal files

and reamers type K only and not root canal files type H, rasps, broaches, probes,

applicators, condensers, or spreaders as included in Group 1 of the developing

international specification. No engine driven root canal instruments are included

in ADA Specification No. 28. The reamers and files of the ADA Specification No.

32

28 are divided into two classes: (A) Carbon Steel and (B) Stainless Steel. The

specification calls for detailed dimensions and tolerances for the diameters, taper,

and tip as well as the length of the spiral cutting section of the instrument. Specific

procedures for the measurement of dimensions are noted. Unlike the international

standard as yet to be developed ADA Specification No.28 includes physical tests

of the instruments detailing the equipment and procedures to record acceptable

limits of resistance to fracture by twisting, stiffness, and corrosion resistance.

Requirements for the packaging and labelling of instruments as well as colour

coding are also included in the ADA Specification.

Work continues on the international level to establish dimensions for all

those instruments other than reamers and files of type K, and the adoption of test

procedures for the physical properties of endodontic instruments of all types.

International activities have concerned themselves with the lengths of the

instruments as measured from tip to handle and have recommended the adoption

of 21, 25, 28 and 31 millimetre lengths with a tolerance factor of plus or minus

0.5 mm and a notation that other lengths may be supplied by manufacturers upon

request.

• Devices for Determining Working Length

Determining and controlling the working length of a root canal during

root canal instrumentation is a recurrent problem in endodontic practice and

several devices have been developed to help solve it. Historically the method of

choice for the determination of the working length of a tooth in endodontics has

been to make a radiograph of the tooth with a radiopaque instrument extending

into the root canal to the apical constriction by digital tactile strength. The

33

measuring instrument is either bent or collared in such a fashion to provide a mark

or stop at an occlusal or incisal reference point, which will then be detectable on

the radiograph. By measuring the length of the radiographic images on both the

tooth and the measuring instrument as well as the actual length of the instrument,

the actual length of the tooth can be derived by a mathematical formula.

Actual length of tooth = Actual instrument length X

Radiographic tooth length = Radiographic instrument length

This principle can be used with measuring probes developed by either

Bregman (1950) or Bramante (1970), each having specially designed occlusal

stops for ready reference both intraorally and on the radiograph. Ingle

recommends measuring a preoperative radiograph, approximating the working

length of the canal by placing a rubber occlusal stop on the shaft of a root canal

file used as an explorer, placing the file into the tooth and taking a second

radiograph. On the resultant film the distance between the tip of the instrument

and the site where the pulp canal leaves the tooth is measured and the working

length is then determined by appropriate adjustments of the rubber stop on the

instrument shaft. Best and co-workers (1960) recommended luting a metal pin of

known length to the surface of the tooth parallel to its long axis prior to taking a

preoperative radiograph. By means of a specially designed transparent “BW

Gauge”, through which the length of the pin and the length of the pulp canal are

measured, compensation for radiographic distortion is accomplished and the

working length of the tooth is determined.

The method of determining the working length of a root canal as proposed

by Sunada (1962) does not require the use of radiographs.84 It is based upon the

experimental studies of iontophoresis by Suzuki in 1942 in which the electrical

34

resistance between the mucous membrane of the oral cavity and the periodontium

were considered to have a consistent relationship. Electrical resistance between

the oral mucous membrane and the periodontal ligament supposedly would also

register a consistent reading when a measuring probe reaches the periodontium via

the pulp canal. This resistance to the passage of an electric current when an

instrument introduced into the root canal reaches the apical area has been found to

be consistent and equal to approximately 6.5 kohms. Several clinical

investigations using a refined instrument of the type used by Sunada have been

reported. This device, the Endometer, measures the electrical potential of the

periodontal ligament with a meter readout system. Inoue (1972) developed a sonic

readout system by using a transistor equalizer-amplifier feedback circuit and low

frequency oscillation to develop the sound. The principle involved in this system,

the Sono-Explorer, is based on transposing the relationship of the periodontium

(and oral mucous membrane) to the tooth structure into the relationship of the

capacitor to the resistor. The device measures the resistance of the patient’s oral

mucous membrane during a probe of the gingival circus. A probe is then inserted

into the tooth until the same resistance is met; at that point, the correct tone is

heard. Another method based upon a grid system known as the Fixatt-everet

evaluation may also be used to supplement the radiographic technique.

Evaluations of the various means and devices used for determining tooth

length indicate that the radiographic methods are consistently the most accurate,

particularly that of Ingle.

The use of the BW Gauge as proposed by Best results in great variations in

measurements as do “actual length-radiographic length” formulas, particularly

when the measuring probes are not placed in close approximation to the apex of

35

the tooth. There are indications that the digital-tactile sense of the operator without

any radiographic references will detect the apical constriction and result in an

accurate determination of the working length 60% or more of the time. Some

clinical reports on the use of the Sono-Explorer indicate sufficient accuracy for

clinical use in less than half the instances in which it was tested, but most reports,

and particularly those in which actual measurements were made on experimental

and control teeth following extraction, indicate a high degree of accuracy ranging

from 83% to 89% of the time in locating the apex. The Endometer seems to be

slightly less accurate but more consistent in its readings when comparable tests

were run. The Endometer is less complicated to use clinically but does require an

assistant to read the meters without parallax, as the operator’s entire attention is

needed to manipulate the measuring instruments within the patient’s mouth. The

sonic tones of the Sono-Explorer can be adjusted so as to be audible to the patient

as well as the operator or conducted through an accessory stethoscope to the

operator alone. Electrode clips, which attach to the measuring instruments on both

devices tend to be cumbersome and the presence of ionizing solutions in the root

canal or extraneous electrical currents can seriously affect the functioning of the

Sono-Explorer. Nevertheless, it would appear.

• Devices for Controlling Working Length

To control the working length of a root canal instrument while it is being

used, several varieties of instrument markers or stops are available. The simplest

36

and perhaps the most common are small pieces of rubber dam or soft plastic

punched out with an ordinary paper punch or clipping from various sized and

coloured rubber bands. Small-multicoloured markers made of nylon or soft

plastics are available commercially from several sources. These rubber or plastic

markers are placed around the instrument shaft by passing the instrument through

them. Also available commercially are instrument stops made of plastic which are

tubular in form and clip onto the base of the instrument handle after the working

blade is passed through them. They in effect extend the length of the handle while

reducing the length of the instrument shaft thus providing a positive marking or

stop. One type has a fine tubular extension that sheaths the instrument shaft and

provides for a stop at the floor of the pulp chamber. These plastic stops are

available in a variety of colours, length, and sizes.95 The Krueger stop is a sliding

metal clip, which fastens to a long handled root canal instrument and projects

forward over the instrument shaft passing through it. Working lengths can be

adjusted by sliding the clip along the instrument handle. A more sophisticated

system is the unigauge test handle and instruments. The root canal instruments,

reamers type K, files types K and H, and rasps type R, are unmounted with a short

portion of the terminal end of the shaft bent in a right angles to fit a specially

designed adjustable handle. The unigauge test handles can be obtained in either

the long or the short design. By means of a knurled locking knot on the forward

portion of the handle combined with a slotted posterior portion of the handle the

length of the working blade is adjustable from 20 to 28 millimetres in length.

While not widely adopted the unigauge test system and its accessory gauges,

wrenches and stands is not without its advocates. It has been reported also that

magnetized steel stops are available but they are not widely used.

37

4. Materials

• Devices for Intracanal Irrigation

It is generally recognized that irrigation during instrumentation is

not only desirable but necessary in most instances.

While sodium hypochlorite with or without the intermittent use of

hydrogen peroxide is used as the irrigant of choice in current endodontic practice,

various types of EDTA solutions and lubricating gels or pastes are often

recommended due to their chelation effects.106-118 Scanning electron microscope

investigations indicate that the particular irrigation solution or lubricating agent

used may not be as important in removing root canal debris as is the volume of the

agent while affirming clinical impressions of the necessity for irrigation when

incrementing a root canal. As the removal of debris seems to be a function of the

quantity of irrigant used rather than the type of solution involved physiologic

saline may well suffice and would certainly be less toxic to viable tissues.

Several technical problems are associated with endodontic irrigation: these

are getting sufficient volume of the solution to the working area of the instrument,

particularly in fine or tortuous root canal systems; aspirating the expended fluid

and debris from the tooth and operating field; and prevention of the extrusion of

either irrigation solution or debris beyond the apical confines of the tooth.120, 121

Numerous devices have been developed to assist the dentist in overcoming these.

The endodontic irrigating syringe is the simplest approach. It consists of a

disposable 3 cc. syringe with a specially designed irrigating needle. The needle is

blunted as well as slit for four or five millimetres along one side from the tip

38

toward the hub so as to provide an escape for fluids should the needle bind in the

root canal. Without this feature, the root canal would in effect become an

extension of the irrigating needle if the needle were forced to place. Excess fluid

overflowing from the tooth onto the rubber dam is generally absorbed by either

cotton rolls or gauze pads when an irrigating syringe is used. Dental evacuation

and suction devices are frequently used to aspirate excess irrigating fluid from the

tooth under treatment or the surface of the rubber dam surrounding it, particularly

when dental assistants are utilized. A modification of the endodontic syringe has

been proposed wherein the needle passes through the wall and lumen of a

polyethylene tube, which in turn is connected, to the saliva ejection system of the

dental unit to provide aspiration during irrigation.

The Endovage syringe is a device specifically designed for root canal

irrigation It. consists of a pistol shaped syringe which is also connected to the

saliva ejection system of a dental unit. The syringe contains a patented valve

system that provides for continuous aspiration until the operator activates the

injection phase of the device by pressing the plunger located above the handgrip,

which then slides into the syringe barrel, which holds the irrigant. The Endovage

syringe is capable of forcing solutions through any one of a number of sizes of

needles which can be selected to fit the device. Aspiration occurs through the

irrigating needle by way of a saliva ejection system once pressure on the syringe

plunger is released. Numerous claims for efficacy and safety have been made for

this device but have not yet been substantiated by scientific evidence. A similar

but much more sophisticated device in which the injection phase was actuated by

compressed air and aspiration was independent of other dental unit systems has

been withdraw from the market after questions of safety were raised by

39

Consultants to the Council on Dental Materials and Devices of the American

Dental Association.

Several severe injuries have been caused by the inadvertent injection of

irrigating solutions in periapical tissues during endodontic procedures. Air

embolism in tissue have also been reported because of syringe blowing

compressed air into the open root canals teeth.128 The possibility of a fatal reaction

by this means has been demonstrated in dogs. The severity of the reaction due to

irrigating solutions passing beyond the confines of the apex of the root canal is

dependent upon the volume injection, the toxicity of the solution itself, and the

location of tissue receiving the insult. Instrumentation of teeth flooded with

irrigating solution by larger sized instruments (sizes 45 and above) has been

shown to increase the potential for extruding debris and irrigants beyond the apex

in experiment situation.121 Selection of the type of irrigating solution to use, the

device for using it, and the safest method for a particular clinical procedure

involving irrigants should be made with these hazards firmly in mind.

• Devices for Root Canal Filling

As indicated previously, root canal filling condensers and spreaders are

available in a variety of sizes and handle designs. Several types of root canal

pliers, cutters and forceps are available to meet the needs of sliver point and gutta

percha root canal filling techniques. Referral can be made to any of the general

catalogs of instruments available from endodontic supply houses for details of

these as individual preferences in instrument design and function vary

considerably. However, paste root canal fillings or root canal sealers present

somewhat different clinical problems and instruments have been designed

40

specifically for use with them. Pastes or sealers are mixed to a readily flowable

consistency if they are to be used with the paste carrier (Lentulo) as stiff mixes

render the system inoperable. Thicker mixes on zinc-oxide-eugenol cement have

been recommended for obturation of the root canal in surgical cases or the

deciduous dentition where the consequences of extruding filler beyond the apex of

the tooth or in completely filling the root canal are not as serious as in

conventional intracanal techniques. Jiffy tubes have been found by most clinicians

to be less than satisfactory. Disposable syringes designed for use with elastic

impression materials do not allow for the extrusion of mixes of the desired

consistency. Disposable 1 ml tuberculin syringes which due to their size and

construction allow thick mixes to be expelled from modified 11/2 inch 18gauge

disposable needles or plastic rubber base injection tips cemented to the syringe

have some merit for this purpose. The thicker the root canal paste or cement the

more dense and stable the ultimate root canal filling will be. The Pulpdent

pressure Syringe designed by Greenberg and Katz is capable of placing controlled

amounts of very heavy paste into all sizes of root canals. Originally recommended

for the deciduous dentition it has been adopted for use in the selected cases

occurring in the permanent dentition particularly those involving incomplete

apical formation, fine and tortuous root canals, and retrograde root canal fillings.

The device consists of an internally threaded octagon shaped syringe barrel with

one end machined to receive blunt tipped needles with threaded hubs and a screw

type plunger with a knurled handle at one end. Filling paste or sealer is placed into

the hub of a needle selected to suit the size of the root canal to be obdurate, (i.e.: a

30 gauge needle corresponds to root canal instrument sizes of from 15-30, 25

gauge to instrument size 50, and 18 gauge to sizes from 100-110 approximately).

41

Seven sizes of needles are available from 30 gauge to 19 gauge for use with the

device. The paste laden needle is screwed onto the syringe barrel forcing some

material into the barrel itself. Additional paste can be added by repeating the

procedure of filling the needle hub and screwing it onto the syringe barrel. The

screw type plunger is inserted into the open end of the syringe barrel and turned

clockwise until the compression forces created cause paste to appear at the needle

tip. The handle of the plunger has four lines upon it indicating the distance of a

quarter of a turn of the screw. By careful manipulation of the plunger

predetermined lengths of paste can be exuded from the needle tip. An accessory

wrench is supplied which not only assists in tightly screwing the needle to place

but can also be used as a handle for the device when its closed end is slipped over

the syringe barrel with the bend of the wrench directed away from the operating

field and patient. This device has been shown to be the most effective for the

purposes for which it was intended.132, 133 Pastes as thick as those used for

temporary coronal restorations can be used with it provided the mesh size of the

zinc oxide or other base particles allows for flow through narrow apertures.

• Root Canal Filling Materials

The most universal root canal filling material until the middle of the

twentieth century was gutta percha in solid forms or in a multitude of solvents.

Despite widespread usage no scientific studies on the physical properties of gutta

percha were available until the exhaustive report of W.A. Price appeared in the

December 1918 Journal of the National Dental Association. They were principally

concerned with the physical changes occurring in gutta percha due to heat,

concluding that a contraction of from one to two percent occurred if the material

42

were heated to 75o at the time of insertion. An opinion that solvents such as

chloroform, eucalyptol, or chloroform resin mixtures, were better than heat for

inducing plasticity in gutta percha if it was to be used in root canal filling was

expressed although it was noted that teeth filled with combinations of solvents and

gutta percha showed significant losses of volume and loss of adhesion to the root

canal wall when the solvent evaporated, shrinkage taking place toward the center

of the material mass and away from the tooth. Although the introduction of rosin-

chloroform preparations by Callahan and eucapercha (gutta percha dissolved in

eucalyptol) by Buckley were designed to reduce shrinkage problems, the ultimate

result was the same regardless of the solvent used, according to Price. He also

noted that a skin formed on the surface of chloropercha compounds, especially

chloroform rosin combinations, while under the surface skin the liquid retained all

its original fluidity because of vapour control by the surface membrane film.

Therefore, many months will elapse before these mixtures will obtain maximum

contraction and solidification into honeycombed masses. Muchbinder reporting in

Dental Cosmos in 1931 verified these earlier observations by experimenting with

various root canal filling materials packed into glass tubes. The modern era of root

canal filling materials began with a series of studies reported by U.G. Rickert and

C.M. Dixon in the 1930’s. Their presentation of the “hollow tube” concept in 1931

was followed by tissue tolerance studies of dental materials in 1933 and histologic

verification of the results of root canal therapy in experimental animals in 1938, in

which they summarized all known results of root canal experimentation. It was

through these investigations that the Rickert formula root canal sealer was

developed and tested.

43

Evaluation of the efficacy of root canal fillings and materials by the use of

radioisotopes and dyes kindled interest in root canal sealing investigations in the

last 1950’s and newer fluorescing dyes and scanning electron microscope

techniques appeared in the literature of the 1960’s and 1970’s. Although the

methods of evaluating the biocompatibility of endodontic filling materials have

technically improved with the development of intra-osseous and cell culture

techniques as well as refinements of the subcutaneous and intramuscular

implantation techniques used by Rickert and Dixon and their contemporary E.P

Boulger (1933), the basic premises they laid down remain valid. Surprisingly, few

investigations of the physical properties of endodontic filling materials have

appeared in the literature in the half century since Price. McElroy noted in the

Journal of the American Dental Association in 1955 that few of the numerous

clinical claims for root canal filling materials were supported by clinical evidence

and very little data existed concerning the physical properties of endodontic

materials. This situation did not change significantly except for annotations to

other types of studies until the work of Higginbotham appeared in 1967. Since that

times significant gaps in our basic knowledge are being filled as more advanced

education programs in endodontics recognize them and acquire the expertise of

biomaterial researchers.

• Root Canal Filling Methods

44

The methods used most frequently to seal the root canals in teeth in the

current decade can best be classified and described by referring to the basic core

material used in the technique.

The single silver cone cemented to place with a suitable root canal sealer

enjoys some popularity today but has undergone several modifications. The

cemented central core of silver is not infrequently surrounded by laterally

condensed cones of Gutta Percha in a common modification, although laterally

placed cones of silver have been used on one technique variant to accomplish this

same end. The second technique using silver cones is to section the cone in such a

manner that the cone will obturate the apical one-third of the root only, and the

middle and cervical thirds are then filled with gutta percha or utilized in the

preparation of space for cores or dowels for coronal restorations. Usually this

sectioning is accomplished by notching the cone at the point at which

segmentation is to occur, stain hardening the weakened area after cementation in

the tooth, and subsequent removal of the occlusal or incisal portion after fracture.

The cone can also be precut into apical and occlusal portions and the apical

portion seated with cement by using the occlusal portion as a plugger.

Specially designed precision threaded apical cones have been developed

and are available commercially which accomplish this sectioning with more

surety, seating the entire cone and then unscrewing the cemented apical tip from

the occclusal shaft. Gutta percha is undoubtedly the most widely used root

canal filling material in dentistry today as it has been for over a century. It can be

used in the form of a filling cone cemented into the root canal in the manner

described for a silver cone or it can be used as a cemented master cone surrounded

by laterally condensed cones. It also can be fitted to the canal, sectioned, and

45

condensed apically as a series of segments in conjunction with heated plugggers, a

root canal sealer, or any one of several solvents. A modified technique uses a heat

carrier to soften the material followed by vertical compaction of the cone with

pluggers, repeating the process until the root canal is obturated. In the Johnston-

Callahan or diffusion techniques, the root canal is looded with 95% alcohol for 2-

3 minutes, dried, and flooded with a chloroform solution of rosin gutta percha.

Gutta percha cones one after another are then inserted into the solvent flooded

root canal with a churning motion until they no longer dissolve in the gradually

thickening paste. Techniques using eucapercha or other forms of solvent are

similar to this with or without the used of root canal pluggers to apply apical

compaction of the material. Of particular importance is the chloroform-rosin-gutta

percha sealer cement (kloropercha) technique introduced and popularized by

Nygaard which is used extensively in Scandinavia and much of Europe.

One additional approach to root canal filling needs mentioning that is

the use of root canal filling pastes or sealers without solid cores. These

techniques usually involve the use of root canal paste carrier (lentulo) or devices

designed for injection techniques such as modified tuberculin syringes or the

endodontic pressure syringe. Any paste or cement suitable to the device to be

used for its placement into the root canal can and has been used but due to a lack

of control in accurately terminating the resultant root canal filling the trend is to

select either materials which obtund clinical symptoms or less frequently materials

which are highly bio-compatible. These techniques are also used in cases in which

the more usual root canal instrumentation, cleansing and shaping, or preparation

techniques are not applicable such as in cases of incompletely formed or desorbed

46

apices. As there is no one best instrument suitable for all cleansing operations

there is no one best root canal filling material or technique situations.

• Efficacy of Root Canal Fillings and Materials

A number of authors have evaluated the efficacy of root canal fillings

and materials by means of means of dye or radioisotope penetration studies of not

dissimilar design, none more extensively than Marhall and Massler.

Such methods have been used ostensibly to demonstrate either the

superiority of one root canal sealer over several others or the sealing ability of a

newly introduced root canal sealer, without much if any consideration being given

to the root canal filling technique in which the sealers were employed;

consequently, results vary from report to report. Usually these studies involve a

technical refinement of a previous method and fail to explore the physical

properties of the test materials or their relationship to the efficacy of the seals

obtained. Scanning electron microscope investigations of root canal filled teeth

attempt to ascertain the effectiveness of the seal by visualization of the interface

between the core material and sealer as well as between the sealer and the dentinal

surface of the root canal wall. These investigations are difficult to qualitate and

subject to much experimental error although they do provide fresh insights into

the problem.

Messing, in a fluorescent dye investigation of the sealing properties of

some root canal filling materials, sums up the situation by concluding that a good

seal is possible with any method of root canal treatment followed. The same

conclusion applies with rare exceptions to the materials used in root canal filling.

47

• Root Canal Core Filling Materials Gutta Percha

Gutta percha, the purified coagulated exudates from “mazur wood trees”

indigenous to the islands of the Malay Archipelago, has been used in dentistry for

over a century and a quarter. From its introduction to Europe in 1843, this

naturally occurring polymer enjoyed widespread popularity much as the

introduction of synthetic polymers has in our own century. Gutta percha as a pure

substance was first found to be useless in dentistry but the discovery that its innate

hardness could be altered by the addition of zinc oxide, zinc sulphate, alumina,

whiting precipitated chalk, lime or silex in various combinations increased its

potential as a restorative material. Attempts to use the polymer with various inert

fillers as a permanent restorative material proved futile by the middle of the 19th

century, but its use in temporary restorations continued unabated for over a

hundred years. As a root canal, filling material reports from as early as 1865 has

been recorded.

Before the addition of waxes, fillers, and opacifiers, gutta percha is a

reddish-tinged grey translucent material, rigid and solid at ordinary temperatures.

It becomes pliable at 20o -30oC, a soft mass at 600 C, and melts at 1000 C with

partial decomposition occurring.

Gutta percha is 60 % crystalline at ordinary temperatures, the remainder

of the mass being amorphous in nature. It exhibits a property common to

polymers; viscoelasticity, that is, elastic properties and the properties of a viscous

liquid simultaneously. If the naturally occurring “alpha’ form of crystalline gutta

percha (Trans-polyisoprene) is heated above 65oC it becomes amorphous and

melts. If this amorphous materials is cooled extremely slowly, (0.5oC per hour or

less) the “alpha” form will recrystallize. Routine cooling of the amorphous melt

48

results in crystallization of the “beta” from which occurs in most commercial gutta

percha and which becomes amorphous on reheating at lower temperatures than

does the naturally occurring material. This complex admixture of ‘alpha” and

“beta” crystalline forms, crystalline and amorphous states in the same mass, as

well as the purity, molecular weight, compounding, and mechanical history of the

batch, will all affect the temperature related volume changes and the related

physical properties of gutta percha.

Gutta precha points used as root canal core filling materials have been

reported to contain either 17% gutta percha, 79% zinc oxide, and 4% zinc silicate

or 15% gutta percha, 75%zinc oxide, and 10% waxes, colour agents, antioxidation

agents, and opacifiers. Chemical Analysis on five currently used brands of

endodontic points revealed gutta percha contents of from 18.9 to 21.8% zinc

oxide, from 59.1 to 75.3% heavy metal sulphates from 1.5 to 17.3%, and waxes

and resins in amounts of from 1.0 to 4.1%. The ratio of gutta percha and organic

waxes and resins to zinc oxide and heavy metal sulphates appears to be a fairly

constant one, despite variations in the specifics of either the organic or inorganic

components of the material. In spite of the secrecy surrounding the composition of

the material it is reasonable to assume that gutta percha endodontic points are

composed of approximately 20% gutta percha, 66% filler, 11% radiopacifier, and

3% plasticizer. The appearance of the material under SEM examination

collaborates the chemical analysis. Deformation of gutta percha endodontic points

in tension and plods of the resultant stress stain curves reveal the elastic and

plastic characteristics of the material. The mechanical properties demonstrated

correspond to those of a typical viscoelastic, partially crystalline, material. In spite

of the large proportion of metallic oxides and sulphates contained in dental gutta

49

percha the mechanical properties are consistent with other viscoelastic strain rate

sensitive materials having partially crystalline polymeric structures.

Compressibility values obtained for dental gutta percha in triaxial testing

proved to be less than that of water which is considered, for all practical purposes,

to be incompressible. Below these levels of pressure there was compaction of the

material due to consolidation and the collapse of internal voids as could be

predicted from high power SEM examinations. Contrary to empirical clinical

claims no molecular “spring back” can be expected to assist in sealing the dentin-

gutta percha interface by condensation techniques advocated for gutta percha root

canal fillings.

Several other aspects of the physical properties of gutta percha have been

reported. Penetration of a gutta percha sample by a modified Gilmore needle

apparatus shows a continuous distortion of the material with constant pressure

expressed over a period of time. The rate of penetration was approximately one

half that of the initial rate after 0.3 of a minute has elapsed and little change in the

rate occurred after the passage of 0.6 of a minute, a funther demonstration of the

viscoelasticity of the material. When gutta percha eas compressed into closed

containers and then recovered after a week or a month, 6.8% and 3.1% increases

in the volume of the material were recorded as compared to the measurable

volume of the containers. This would appear to support the compaction data

associated with the material. The resistance of the material to penetration by a

modified Gilmore needle is affected by the temperature of the material. There is

an increase in resistance as well as hardness and/or stiffness with a decrease in

temperature at a fairly uniform rate. Gutta percha also undergoes linear expansion

with increase in temperature. A gutta percha point cooled to 15oC would undergo

50

three-fourths of its expansion by the time it reached body temperature (37oC).

Attempts to utilize the increased stiffness and subsequent expansion of gutta

percha by freezing gutta percha root canal points prior to use by means of

ethychloride spraying have not been widely adopted as retention of these

properties by the frozen point in room temperature of 27oC have been found to be

approximately three seconds. Carrying heated instruments into root canal partially

filled with gutta percha in order to make use of these temperature related

properties probably does have some effect over short distances but the overall

result is inconclusive as a temperature rise of 4oC or less has been measured at the

apex of simulated root canals at the time of completion of warm gutta percha

condensation techniques. Since gutta percha remains solid at temperatures higher

than body temperature by 10oC or more alterations of temperature within the root

canal during root canal fillings are most likely insignificant in clinical practice.

Alterations of gutta percha by the use of chemical solvents has had a long

history in root canal therapy as previously noted and there can little doubt as to the

effectiveness of such techniques in duplicating the intricate internal anatomy of a

root canal system. The lack of dimensional stability in the material as the solvent

is lost from the mixture is also well known.

Those physical properties of the gutta percha needed for the negotiation of

the root canal with a filling point are opposed to the physical properties of the

material required for the compaction of the material in the root canal space once it

is negotiated.

This is true whether one is considering gutta percha point as core material

or gutta percha based pastes, as the stiffer the point the less compactible it is or the

more fluid the paste the higher the shrinkage potential it has. While it may be

51

possible at some future date to manufacture and market gutta percha root canal

filling materials with varying chemical compositions, and hence differing

mechanical properties, allowing a selection of a specific type for the clinical

situation at hand, mush as the practitioner selects gold for his castings, gutta

percha as presently used in endodontics remains an anachronism.

• Silver Cones

Metals have had a long history as root canal filling materials, the use of

gold or lead dating to as early as 1757 where they were used to fill the root canals

of extracted teeth prior to re-implantation. In the nineteenth century gold wire and

gold foil were commonly used as root canal filling materials. Tin foil, lead wire

and cones, silver and copper amalgam, and gold-tin alloys have been

recommended at one time or another. The acceptance of silver as a root canal

filling material is relatively current and coincides with the dental profession’s

reaction to proponents of the focal infection theory as it was applied to

endodontics. One of the reasons for the selection of silver in deference to other

metals aside from its availability and physical properties was undoubtedly its

bacteriocidal effect to as its “oligodynamic” property. The term “oligodynamic”

dates from the 1890’s and refers to the toxic effect of exceedingly small quantities

of substances in solution upon living cells. In the 1920’s and 1930’s silver having

this property was widely recommended. The mechanism of activity was though to

be unrelated to the volume of the metal but rather to surface area of soluble silver

salts. The bactericidal effects were due to the affinity of silver ions of

sulfhydrylenzymes, presumably leading to the formation of hemi-silver sulfides

with the sulfhydryl groups and ultimately protein denaturation. Also silver

52

combines with other biological moieties such as amidazole, carboxyl, and

phosphate groups. Prior to the introduction of sulfonamides and antibiotics silver

was widely used for the control of venereal disease.

As used in endodontics, silver is manufactured into tapering points or

cones designed to match intraradicular tooth preparations and to be used in

conjunction with root canal sealers to cement them into the root canal. The surface

texture and physical shape of silver points varies considerably by manufacturer.

Preciseness of shape affects accuracy of fit and surface texture affects both cement

adherence and corrosive potential.

Despite manufacturing differences the chemical composition of commercial

brands was found to be similar and potentiostatic investigation showed no significant

difference in their corrosion behaviour in 0.9% NaCI, Ringer’s solution, or serum.164

The silver content of these points ranges from 99.8 to 99.9% with nickel and copper

the elements in next highest concentration, 0.04-0.15% and 0.02-0.08%, respectively.

Nickel and copper have not been detected in the corrosive films studied.164 The

hardness values for silver points average 112 Knoop hardness number, corresponding

to a region of Knoop values expected for cold worked samples of commercial grade

silver (99.9%). The microstructure of endodontic silver points is indicative of cold

drawn wire with an etched surface similar to that of 99.9% silver which has been cold

rolled. The tensile strength values of 306.7 MPa (44,491 p.s.i.) to 449.5 MPa (65,194

p.s.i.) determined for endodontic silver points fall in the range of values expected for

cold worked silver. The mechanical data available indicate the degree of cold working

associated with silver points probably lying in the range of 20-50%. Values for

percent of elongation, proportional limit, and modulus of elasticity have been

determined but are suspect due to induced experimental errors.

53

The corrosion behaviour of silver points has been investigated by standard

potentiostatic techniques as well as observed in SEM investigations. Silver has been

found to corrode spontaneously in a sulphide medium at -450 mv and to corrode in a

chloride medium at 100 mv. The corrosion films formed were noncontinuous,

nonpassivating, and allowed corrosion to continue at high current densities. In serum

two separate, slightly passivating regions are observed at approximately 200 mv and

400mv. The first is thought to be due to the formation of AgCI and the second region

due to either the formation of Ag2 CO3 or Ag2 O. Sealers will protect a silver point

extended into tissue for a short period of time until the properties of the sealer are

altered by the periapical tissues. Eugenol USP, a common ingredient of sealers, is

noncorrosive to silver. Corrosion of a silver point can be limited by sealing the point

entirely within the root canal, surrounded and protected by sealer. In situations in

which the point represents a connective tissue implant beyond the confines of a tooth

a material which is electrochemically inert or one which passivates by the formation

of a continuous surface film would be preferable to silver.

• Root Canal Sealers and Cements

Whether the root canal core filling material is gutta percha or silver it is

used most clinical circumstances with a root canal sealer or cement. With the

exception of those root canal sealers which contain gutta percha solvents, such as

eucapercha or chloropercha and their variants, which result in a chemical union of the

sealer with the core material, the bond between sealer and core matrial is a

nonadhesive one.

The core-sealer root canal filling techniques therefore involve a material

interface between the core and the sealer and a second interface between the sealer

54

and dentin. With these techniques it is doubtful that the use of accessory cones in any

way alters this relationship. Hence, the mass of root canal filling consists of the core

and/or accessory cones separated from each other by a thin film of sealer, and a film

of sealer between the mass of the root canal filling and the root canal wall. One of the

objectives of these techniques is to maximize the amount of core material, and thus

achieve dimensional stability of minimizing the amount of sealer that binds the mass

to gether and to the tooth. This critical relationship of core material to sealer has been

demonstrated upon several occasions wherein the adherence of sealing material to the

tooth structure may be at variance to its adherence to the core. Investigations of the

physical and chemical properties of root canal sealers and cements are therefore of

prime importance to our understanding of technical endodontics.

• Zinc Oxide-Eugenol Cement and Sealers

Several type of root canal sealers have been formulated for use in

endodontics. The most common types in current usage are based upon zinc oxide

eugenol formulations. These include Kerr Sealer (Rickert formulation) ProcoSol

Sealers (Grossman’s formulations), and Wachs paste. The Rickert formula was

developed in 1931 as an alternative material to the chloropercha and eucapercha

sealers of the period. As indicated previously gutta percha derived sealers lacked

dimensional stability after setting. It was to eliminate this problem that the Rickert

formula was developed. Several versions of the formula have been reported and

the range of ingredients in the power component have varied somewhat since its

introduction. The Rickert formula has a relatively rapid setting time and as a

consequence has, upon occasion, presented problems in clinical practice. The

55

Grossman formula appeared in 1936 to overcome this. The formulas do not differ

in essentials.

In the Rickert formula the power consists of zinc oxide, silver

(precipitated-molecular), oleo-resins, and (dithymol) iodide and the liquid oil of

cloves and Canada balsam whereas in the Grossman formula the power consists of

zinc oxide, silver(precipitated-molecular), hydrogenated rosin, and magnesium

oxide and the liquid eugenol and Canada balsam. The percentage of ingredients

varies somewhat in comparison of one formulation to the other. A second criticism

of the Rickert formula lay in its use of precipitated silver as a radiopaque agent.

Such a material tends to stain dentin and thereby compromise the esthetics of an

endodontically treated tooth, whereupon Grossman revised his formula in 1958 by

using bismuth subcarbonate and barium sulphate as the radiopaque agents.

This formulation was marketed for many years as ProcoSol Non-staining

Root Canal Cement . The Grossman formula has been revised more recently by

the addition of sodium borate to the power component and the elimination of all

ingredients but eugenol from the liquid component.1 This is essentially how the

material is formulated today whereas Kerr Sealer (Rickert) remains largely

unaltered since its introduction nearly forty-five years ago. These two root canal

sealers enjoy the most widespread popularity among those of the zinc oxide types.

Wachs paste, a variant of a zinc oxide-eugenol formulation, was originally

compounded in 1925 but did not receive widespread adoption until its publication

and reintroduction circa 1955. It is now marketed under several commercial brand

names with minor variations in formulation. Tubliseal was introduced by the Kerr

Manufacturing Company in 1961 as an alternative to their Rickert formulation. It

is a two paste system as contrasted to the power-liquid systems of the other zinc

56

oxide types. The exact formulation is a trade secret but from available literature an

approximation is: zinc oxide, oleo resins, bismuth trioxide, thymoliodide, and oils

and waxes in the base and eugenol, polymerized resin, and annidalin in the

catalyst.

Zinc oxide sets by a combination of chemical and physical processes

yielding a hardened mass of zinc oxide embedded in a matrix of long sheathlike

crystals of zinc eugenolate [(C10 H11 O2 )2Zn]. Excess eugenol is invariably present

and is absorbed by both the zinc oxide and the eugenolate. The presence of water,

the particle size of zinc oxide, pH, and additives all are important factors in the

setting reaction. During the setting reaction of zinc oxide eugenol cements a

concurrent sorption of eugenol takes place. Hardening of the mixture is due to the

zinc eugenolate formation while the unreacted eugenol remains trapped and tends

to weaken the mass. The method of preparation of the zinc oxide is closely related

to the setting time of zinc oxide eugenol mixture. Increases in temperature of

humidity decrease setting time. The longer and more vigorously the mixture is

spatulated, the shorter the setting time. Setting time can also be increased by

decreasing the particle size of the zinc oxide. Usually free eugenol remains after

the setting of zinc oxide eugenol cements, including root canal sealers, and the

comparative hardness of fresh dentin exposed to zinc oxide eugenol sealers is

increased in direct proportion to the amount of free eugenol available. The

significance of free eugenol is most apparent in increased cytotoxicity rather than

through alteration of the physical properties of dentin.

• Non-Zinc Oxide Eugenol Cements and Sealers

57

A second category of root canal sealers and cements includes those not

based on zinc oxide eugenol formulations.

Kloropercha N-0 was introduced circa 1939 from Norway and is similar to

several empiric domestic formulations which date to the early 1900’s

Chloropercha (Moyco) is a direct descendant, relatively unaltered, of materials in

use for nearly a century. Diaket is an organic polyketone compound introduced in

Europe by Schmitt (1951). It enjoyed some popularity in the United States

following favourable concerning its superior strength and physical properties by

Steward (1958) and Bjorndal (1960). The material consists of a very fine powder

and a thick viscous liquid. The resin resulting from the mixing of the components

of the sealer is very tacky in texture, adheres readily to tooth structure, and is

often difficult to manipulate. As a polyvinyl resin, Diaket is essentially a keto-

complex in which basic salts and metal oxide react with neutral organic agents

forming polyketones which in turn unite with metallic substances in the material

to form cyclic complexes which are insoluble in water but dissolve in organic

solvents or chloroform. AH-26 introduced in Europe by Schroeder (1957) is an

epoxy resin adopted for use in endodontic therapy. An araldite epoxy-resin used

commercially as an industrial adhesive and insulator with the addition of a

hardener, hexamethylene tetamine makes the cured resin chemically and

biologically inert. As an endodontic sealer it has several proponents who have

demonstrated favourable properties.

58

• Therapeutic Cements and Sealers

The third category of root canal sealers and cements includes those for

which therapeutic properties are generally claimed. These materials are usually

used without core materials and hence are either introduced into the root canal by

means of a Lentulo spiral or some type of injection device. The claim is made,

particularly for those formulas containing either par formaldehyde or iodoform (as

well as other powerful and toxic antiseptics), that failure of the materials to

provide a compact root canal filling is compensated for by their prolonged or

permanent therapeutic properties. Riebler paste is the most extreme example of

this type of agent while Mynol CementR and Lodoform paste are somewhat similar

in their composition and usage either as cements or as sealers used in conjuction

with core materials. Endomethasone and N2 (Sargenti) are similar in that they

contain, in addition to par formaldehyde, corticosteroids in an attempt to alleviate

the severe postoperative complications that not infrequently accompany these

types of materials particularly when inadvertently extruded through a tooth apex.

N2 goes one step further in that includes lead tetroxide which by increasing its

radiopacity not only gives the illusion of greater compactness of the filling once

inserted but apparently also contributes to the extreme hardness and insolubility of

the final set of the material.

Calcium hydroxide pastes have also been formulated for use as root canal

filling materials. These are used as therapeutic temporary or interim root canal

fillings in instances where continued tooth root development or osseous repair is

desired prior to the insertion of permanent root canal fillings. These pastes have

achieved some modicum of success when used in this manner. Pastes of calcium

59

hydroxide and sterile water are often used in vital pulpotomy procedures for much

the same.

• Physical Properties of Root Canal Cement and Sealers

There have been relatively few investigations of the physical properties of

root canal filling materials. Those that have provided data comparable to the data

available for other types of dental cements can be summarized as follows.

The setting times in minutes recorded by various investigators at differing

temperatures and relative humidity range from 21 minutes at 100o RH and 82o F to

no set at all at 99oF in air. Since most of the root canal sealers investigated are zinc

oxide eugenol types the comparative data are not unexpected.* The increased

setting times for the Grossman formulations as contrasted to Rickert’s formula is

apparent with some instances recorded in which they fail to set at all. The surface

film set of chloropercha without internal setting is also noted. Setting times were

determined by the failure of a 46 gram spatula to indent the surface, failure of a ¼

pound Gilmore needle to penetrate or other tactile determinations. Setting times

can be related to handling properties and tissue irritation potentials.

The flow rate of the sealer has been determined by Weisman who

measured the aspiration of sealers into pipettes under a vacuum of 28 inches of Hg

applied for 15 seconds. The flow rate may be related to the ability of the sealer to

penetrate the recesses of the root canal system prior to setting.

The film thickness as measured by a modification of ADA Specification

No.8 for Dental Zinc Phoshate Cement has been reported. It should be noted that

the maximum allowable film thickness for fine grain (Type 1) zinc phosphate

cement is 25um and that Diaket exceeds this value while Rickert’s formula

60

approaches it. The film thickness of the sealer may be of considerable in gutta

percha condensation techniques.

The solubility of sealers in distilled water and 0.0001 molar acetic acid

buffered to pH 4 is known from suspending tablets of the material having surface

areas of 229 square millimetres in crucibles containing 25 millimetres of solvent

for this test. The water absorption of the sealer as determined by immersion in

distilled water for 48 hours has also been reported. Weiner and Schilder

investigated the volume chage of sealers at seven, thirty, and ninety days after the

insertion of fresh mixes into micropipettes. The relative stability of the Rickert

formula thirty days and thereafter when compared to other sealers is apparent as is

the failure of the nonstaining Grossman formula to set at all under these

conditions.

An index of the radiopacity of the materials has been measured by

radiographing a specimen 1.1 millimetres thick at 65KVP and 10 mas. With

Kodak ultra speed occlusal film and processing at optimal times and temperatures.

The resultant images were compared by a reflection transmission densitometer.140

When examined by this method an equivalent specimen of gutta percha has a

value of 0.34 and one of silver a value of 0.78. The higher the value the more

radiopaque is the material.

• Tissue Toxicity Tests of Endodontic Materials

Of concern to dentistry for many decades has been the tissue toxicity of

endodontic filling materials since they are placed in direct apposition to the

connective tissues of either the pulp or periapex when used clinically. These

concerns for the biocompatibility of dental materials have consumed a great deal

61

of time and effort on the part of the endodontic researchers and have been

extended to all types of materials used in dentistry. Until relatively recently no

standard protocols existed for the biological evaluation of dental materials. Root

canal filling materials are classified as Type IV materials under recommended

standards for biological and clinical evaluations. The requirements for Type III

(materials that might affect the health or vitality of the dental pulp of soft adjacent

tissues) and Type IV materials involve testing for (a) acute systemic toxicity, (b)

mucous membrane irritation, and (c) irritation of the pulp. Recommendations for

the clinical evaluation of dental materials have also been developed but as yet

have not been applied to endodontic filling materials.

There are no reports in the literature of endodontic filling materials having

been tested for acute systemic reactions.

Contact irritation testing as applied to dental materials usually involves the

evaluation of mucous membrane irritations. The testing of liquids, such as root

canal medicaments and freshly mixed filling materials has been done by dropping

the substances into the eyes of rabbits, but there are no reports of mucous

membrane contact irritation studies being done for endodontic filling materials.

Implantation responses have been the preferred method of evaluating

endodontic filling materials. The various methods of handing the material for

implantation include the implantation or injection of fresh mixes, the implantation

of test pellets made of the set material, or the use of polyethylene or Teflon

containers for the material. Various atraumatic techniques involving different body

tissues and sites have been developed and reported. Freshly mixed materials are

invariably shown to be highly irritating to tissues. As the material sets its

components are bound into masses which will often show a high degree of

62

biocompatibility although the surface area of the mass will remain an uncontrolled

variable as when a freshly mixed material is injected. To overcome this problem

polyethylene tubes having specified internal diameters are filled with material and

implanted thus limiting the contact area of the material with the surrounding

tissue. In intraosseous studies the use of Teflon cups performs the same function

as does the use of polyethylene tubes in soft tissue investigations. Polyethylene

and Teflon containers have and additional advantage in implantation studies in

that the surface of the plastic acts as a control due to its high degree of acceptance

by body tissues. The location of the implant and into what type of tissue it being

inserted can influence the results of the investigation. Soft tissue implantation is

generally done either subcutaneously or intramuscularly, neither site or tissue

being comparable to the clinical situation in which endodontic filling materials are

used. Osseous implantations are more analogous to the clinical conditions and the

tibia or jaws, particularly the mandible, are favourite sites for these types of tests.

The closest approximation to the clinical practice is of course the use of teeth

themselves. The implantation of tooth roots having had root canal fillings was an

early form of tissue evaluation which proved to be unreliable. The treatment of

teeth followed by root canal filling and subsequent histologic examination

inevitably involves many uncontrolled variables, the species of animal being used

being not the least of these. The continuous growth potential of rodent incisors for

example does not allow test conditions analogous to the human situation; neither

does the peculiar multicanal apical anatomy of the teeth of dogs or cats. The size

and morphology of the teeth often preclude the use of those instrumentation or

filling techniques that are applicable to humans. Inflammatory and healing

potentials differ from species to species even if anatomical and technical

63

differences can be overcome. The necessity for obtaining block sections, not to

mention sacrifice of the test animal, precludes the use of human studies to obtain

data comparable to that obtained from numerous animal investigations. Brynolf in

her extensive examination of specimens obtained from human autopsies indicates

that the materials and methods used in endodontics are neither as effective nor as

biocompatible as our clinical experiences would lead us to believe.

Most investigations of the cytotoxicity of silver have concluded that even

though diffuse granular pigmentation is present in the tissue surrounding the

implant and the implant itself shows signs of corrosion the material is generally

well tolerated. Cell culture studies have shown a similar tissue tolerance but this

could be anticipated due to the low solubility of silver in the solutions used with

these techniques. The tissue toxicity of the corrosion products of silver points was

reported by Seltzer(1972) and investigations of the relationship of silver corrosion

to tissue have followed. Two studies from medical literature cite the cytotoxity of

silver in bone (Hickman 1953) and brain tissue (Robinson 1961) and are reported

by Taylor. The issue remains controversial as the indisputable nature of the

cytotoxity products of silver and their source is as yet undetermined and the

relationship of the efficacy of the seal to the tissue reaction noted, apart from the

material itself, is contestable. Gutta percha on the other hand has been well

established as a material with low cytotoxicity. Langeland asserts that gutta percha

is the least tissue toxic material used in endodontics and this includes the paste

forms of the material once the solvent has dissipated. The preponderance of

evidence would seem to support this viewpoint.

Paraformaldehyde containing root canal cements have had a long and

intermittent history in dentistry. Paraformaldehyde containing pastes are clinically

64

successful in pulpotomies and deep pulpotomy procedures but their limitations

need to be recognized. Formaldehyde in the presence of vital tissue results in

nonvital tissue. This is the basis of fixing tissues with formalin for histological

examination. Since such incomplete fixation is a slow, low-grade process, pain is

seldom a problem,(unless the material is injected forcibly beyond the confines of

the tooth) and it may appear clinically that “success” has indeed been achieved.217

The consequences of accidentally exuding these materials beyond the confines of

the tooth are often severe, as even their proponents recognize in recommending

compensatory clinical procedures. Lodoform is somewhat less toxic but presents a

similar hazard even though it does not achieve its anti-bacterial activity by cell

fixation as does paraformaldehyde. In addition to the foregoing the inclusion of

heavy metal ions such as mercury or lead is not without danger as these are

disseminated through the body posing particular problems for target organs

remote from the teeth. Corticosteroids used in conjunction with these materials to

suppress clinical symptomology may also pose hazards that are as yet

unsuspected.

Long duration in vivo studies of endodontic filling materials have not been

conducted. The incidence of cellular metaplasia and/or tumor production

associated with these materials evaluated over periods of time that are in excess of

one or two years is unknown. The recent FDA (USA) concern over chloroform as

an ingredient of drug products due to reports of carcinogenic potential in

experimental rodents may have implications in endodontics due to its widespread

use as a gutta percha solvent. Likewise the immunologic consequences of the use

of these materials is unknown. Not only do several of them contain protein

complexes which may well be capable of initating antigen-antibody responses but

65

the presence of substances such as Para-formaldehyde which produce tissue

necrosis and fixation may be capable of autoimmune reactions. The

immunocompetence of the pulp and periodontal ligament has been established but

the effects of endodontic filling materials upon these tissues have not.

In recent years the in vitro use of cell cultures has been developed as a

means of evaluating the cytotoxicity of dental materials in general, and root canal

filling materials in particular. Among the animal cells that have been used for this

purpose are chicken, dog and mouse fibroblasts as well as hamster kidney cells.

Although the use of human fibroblasts has been reported, the more commonly

used human cells are malignant stock cell cultures such as HeLa cells. As a

screening mechanism cell culture reactions are extremely sensitive. The protocols

developed by Spangenberg and his co-workers for the evaluation of fluid or

soluble materials as well as solid or semi-solid materials in which quantative and

qualitative assessments of cytotoxicity can be made based upon the release of Cr

from damaged cells are particularly impressive and comparable to results obtained

from in vivo testing. Several investigators recognizing the extremely important

variable of the length of time that elapses between the initiation of the experiment

and the evaluation of the data have used a series of time intervals in their studies;

however, not all researchers are as careful. The wide variance in the methodology

used is easily discernible and similar discrepancies in establishing the criteria for

the evaluation of the results obtained are also implicit. Conclusions denoting

either the most irritating material or the least irritating material are valid for that

particular report only, as comparisons of one report to another are extremely

tenuous.From this mass of seemingly disjointed data some general conclusions

can be drawn.

66

All endodontic filling materials are cytotoxic when freshly mixed, the

degree of cytotoxicity being directly related to the ingredients contained in the

material. For example eugenol, eucalyptol, chloroform, iodoform,

paraformaldehyde, acids, etc., are all very tissue toxic and this is reflected in the

evaluations of those materials containing them. This apparently is true for such

materials as freshly mixed dental amalgams as well.

The sooner and more completely an endodontic filling material sets, and/or

becomes chemically stable, the higher will be its biocompatibility. Endodontic

sealers having large eugenol contents which result in the continuous presence of

free eugenol not only have retarded setting times but the leaking of eugenol into

tissues effects a long-term tissue irritation. Paraformaldehyde containing pastes

and some of the other therapeutic cements are deceptive in this regard as the initial

inflammatory response appears to be delayed due to either the rapid setting of the

material, the addition of anti-inflammatory agents, or the fixation of tissues, and

then is followed by a steadily increasing tissue reaction as the therapeutic agents

leak out or the viable tissue response to fixed necrotic tissue becomes more

apparent. Encapsulation by extensive layers of connective tissue is not a measure

of biocompatibility but rather indicative of the body’s need to wall off a

continuing low grade irritant. Crane has reported on a zinc oxide root canal sealer

which does not contain eugenol being analogous to non-eugenol containing

periodontal packs currently on the market. It would appear to possess favourable

physical and biological properties for use in endodontics.

67

• Future Directions in Filling Materials.

At the Third International Conference on Endodontics held in Philadelphia

in 1963 Grossman expressed the opinion that the development of simpler, more

accurate and more certain root canal filling materials would be the next significant

break-through in endodontics, as he reviewed the status of plastic root canal filling

materials.

At the same symposium, cores and cements seemed to Buonocore to be a

poor approach to root canal filling as the polymerization of the root canal filling in

situ would be better, if possible, expressing the belief that injectable root canal

fillings would be the path of the future. Subsequently, the use of SilasticR materials

and the hydrophilic acrylic resin Hydron in this manner have shown promise,

whereas the use of polycarboxylate cements as sealers in conjuction with cores

has proved to be disappointing.

The more biodegradable the material is the higher the biocompatibility.

Biodegradable materials have not been extensively explored in endodontics and

need further investigation. Materials which could effectively seal the root canal

system and yet be completely resorbed and replaced by the tissues of the body so

as to create a viable material-soft tissue interface while maintaining a seal may

have an important place in the future of endodontics.

Grossman’s prophecy of over a decade ago would appear to be as

optimistic and valid today despite little apparent evidence of a significant

breakthrough, as yet. Whatever new material is introduced in the future, only

those of known composition should be used.

68

5. ENDO SAFETY SYSTEM

MEITRAC I-III

With this endodontic safety-system, broken fragments can be grasped and

removed successfully, precisely, and quickly, e.g. from root canal instruments, root

filling pins, silver points and root-posts from the root canal. These systems are

designed in such a way that fragments with diameters of 0.05 to 0.50 mm (MEITRAC

I), 0.55 to 0.90 mm (MEITRAC II), as well as 0.95 to 1.50 mm (MEITRAC III) can

be removed safely.

• MEITRAC I is specialised for removal of broken root canal

instrument. (e.g. fragments of a file)

• MEITRAC II is designed for removal of defective root-filling pins and

silver points.

• MEITRAC III serves the removal of root-post fragments in the root

canal.

All MEITARC systems are made of stainless surgical steel. They permit minimally

invasive procedure to preserve sound dental tissue from being damaged. The fragment

to be removed is exposed by the trephine. This instrument is optimally constructed so

that only a minimal amount of sound dental tissue is damaged. The fragment can be

69

grasped easily with the extractor. The newly developed friction-grip chuck enables the

user to transmit traction easily so that even larger fragments can be extracted without

problems.

• Flexible system for secure removal of fragments from the root-canal.

• Deployable in removal of fragments from root-canal instruments,

silver points, root-filling pins and root-posts.

• Controlled and easy handling

• They permit minimally invasive procedure to preserve sound dental

tissue from being damaged.

70

71

MEITRAC II

72

73

74

MEITRIC III

75

MEIPULP TITANIUM PULP PLASTER

76

This pulp plaster of pure titanium is ideally suited as a carrier for

medication and is easy to position accurately due to its concave shape. Placing this

plaster on the exposed pulp reduces pressure and provides a perfectly sterile cover.

The plaster remains permanently as part of the final filling or reconstruction, is

opaque to X-rays thus provides a record of previous treatment on a damaged tooth.

The pulp plaster is easily picked up with tweezers and positioned the same way.

• Rigid, sterile covering for exposed vital dental pulp which, at the same

time, provides medication

• Biocompatible plaster made of pure titanium

• Reduces loading and pressure

• Safe and easy to apply.

77

MEITAN TITANIUM ROOT FILLING POST SYSTEM

This titanium root filling post system seals the root canal optimally

without requiring an additional root filling. This is achieved by the special design

which ensures that the root filling post can be wedged securely in the prepared root

canal. The post is placed in one single procedure. Cores for crowns are much easier to

fabricate because the length of the root filling post can be determined as required. The

root filling post is inserted into the prepared root canal with an ultrasonic unit and a

adapter.

• Bioinert structural-osteotropic root filling post

• Dimensionally stable

• Easy to handle

• Reduces your workload considerably

78

• Placed with instruments and condensed ultrasonically

• The root post is easily re-examined

• Less complications due to excessive condensing

• Radiopaque

• Stabilizes the root and crown-no additional post and core required

• Few instruments required

79

80

MEIPOST I-II TITANIUM ROOT POST SYSTEMS

MEIPOST I-II is an innovative, universal all purpose root-post system for

tooth reconstruction in the anterior and side jaw regions. The pulpal post is made of

biocompatible titanium which offers excellent retension and rotation quality. The

coronal support-construction-post prevents typical fracturing at the cervical juncture

between root and core. At the same time, its constructive features offer a significantly

strengthened position in the root canal. A further advantage is the effective production

of tooth reconstructions with only three sizes of root-post.

The root-post from Meipost I without thread, with its integrated cement

drainage groove allows for a stress free cementation without risk. Dangerous wedge

effects and disruption of the root are herewith certainly avoided.

81

The specially developed self cutting thread of the MEIPOST II root-posts offer

simple and fast anchoring without cementation. The thread is constructed in such a

way that the root canal can not be disrupted.

• Biocompatible root-posts, made of pure titanium

• Coronary shoulders prevent the post from fracturing at vulnerable

junctures

• Flexible and convenient use in the anterior and posterior regions with a

small assortment of 3 post sizes

• Outstanding retension and rotation stability

• Sturdy root pins with cutting thread (MEIPOST II) or integrated

cement discharge groove for tension-free cementing (MEIPOST I)

82

83

MEIPOST II, TITANIUM ROOT POST SYSTEM

84

85

86

MEIPOST III, SECURIT POST SYSTEM

The MEIPOST III Securit post system is a unique system which enables

patients to retain the functions of their natural roots up to old age, even when the

original tooth is seriously damaged. The specially developed POSTAB stabiliser,

which supports the post, prevents the post from loosening or breaking prematurely.

Scientific studies have shown that the lifetime of these security posts is twice as long

as that of conventional ones.

• Retention of original root through to old age

• Virtually no more loosening or breakage

• Applicable even when teeth are substantially damaged

• Withstands horizontal and vertical loads

87

MEIPOST IV TWO-IN-ONE ROOT POST SYSTEM

These new parapulpar threaded pins are the ideal retention for

reconstructive materials for fitting dentures or larger plastic reconstruction fillings.

The innovative two-in-one approach provides a really simple, highly economical

method for inserting the threaded pin.

88

• Ideal retention for reconstructive materials for fitting dentures or larger

plastic reconstruction fillings

• Biocompatible threaded pin made of pure titanium

• Self-tapping

• Thread retains the substance of the original tooth

• Particularly economical due to innovative two-in-one principle.

89

90

A B C

First drill with Twist drill and placed the parapulper pin.

91

D

HEDSTROEM FILES WITH LONG HANDLE

29 MM LONG

92

HEDSTRROEM FILES WITH LONG HANDLE, 22 MM SHANK

93

ROOT CANAL REAMERS ‘GATES’ STAINLESS

ROOT CANAL REAMERS ‘B’

94

ROOT CANAL REAMERS ‘PEESO’, STAINLESS

ROOT CANAL REAMERS ‘PEESO’ STAINLESS

95

PULP CHAMBER BURS

ROOT CANAL REAMERS ‘KOSEL’

96

ROOT CANAL BURS

97

TUNGSTEN CARBIDE SURGICAL CUTTER

98

ENDO BUR, COARSE

99

ENDO BUR, COARSE

Reference:

1. FDI Technical Report, 1982 Endodontic Instruments,

Devices and Materials, Federation Dentaire

Internationale, 64 Wimpole Street, London WIM

8AL, UK.

2. Sargenti, 1987 Efficient Root Canal Treatment, N2

METHOD, Casagrande.

3. Grossman LI, 1970 Endodontic Practice, 7th.edn,

Philadelphia.

100

4. Grossman LI, Endodontic practice, 8th.edn,

Philadelphia.

5. MESINGER; DENTAL ALVEOLE APEX, GERMANY/USA.

(DENTAL Catalogue).

6. Grossman LI,1974 Endodontic practice.8th ed.,

Philadelphia.

7. Ingle, J.I, 1965 Endodontic, 1st ed., Philadelphia.

8. Serene, T.P., Krasny, R. M., Ziegler, P.E.,

Higginbotham, T.L., Longhurst, G.E, 1975 Principles

of pre-clinical endodontics. Kendall/Hunt, 2nd ed.

9. Shoji, Y, 1973 Systematic endodontics. Buch-und

Zeitschriften-Verlag “ Die Quintessenz”.

10. Sommer, R.F., Ostrander, F.D., and Crowley, M.C,

1966 Clinical endodontics; a manual of scientific

endodontics. 3rd ed., Philadelphiy, Saunders.

11. Weine, F. S,1972 Endodontic therapy, 1st ed.,St. Louis.

Mosby.

12.Puterbaugh, P.G. Root canal filling materials. Am.

Dent. A.J.

13. Rickert, U.G., and Dixon, C.M, 1931 The controlling

of root surgery. 8th Internat. Dent. Cong. Tr.

101

14.Torneck, C.D, 1966 Reaction of rat connective tissue

to polyethylene tube implants, Part I. Oral Surg., Oral

Med., Oral Path.

15. Torneck, C.D, 1967 Reaction of rat connective tissue

to polyethylene tube implants, Part II. Oral Surg.,

Oral Med., Oral Path.

16.Goldman, M., Pearson, A. H.A, 1965 preliminary

investigation of the hollow tube theory in endodontics:

studies with neotetrazolium. J. Oral Therap.

Pharmacol.

17.Browne, R. M., Friend, L.A, 1968 An investigation

into the irritant properties of some root filling

materials Arch. Oral Biol.

18.Nygaars-O stby, B, 1961 The role of the blood in

endodontic therapy. Acta Odont. Scand.

19. Nygaars-O stby, B., and Hjordtdal. O, Tissue

formation in the root canal following pulp removal.

Scand. J. Dent.

20.Davis, M. S., Joseph, S.W., Bucher, J. F, 1971

Periapical and intracanal healing following

incomplete root canal fillings in dogs. Oral Surg., Oral

Med., Oral Path.

102

21.Nyborg, H., and Thullin, B, 1965 Healing process after

vital pulp extirpation. Odont. Tidskr.

22.Seltzer, S., Soltanoff, W., Bender, I.B., and Zionitz. M,

1966 Biologic aspects of endodontics. Oral Surg., Oral

Med., Oral Path.

23.Sinai, J., Seltzer, S., Soltanoff, W., Goldenberg, A., and

Bender, I.B, 1967 Biologic aspects of endodontics. II.

The response of periapical tissues to pulp extirpation.

Oral Surg., Oral Med., Oral Path.

24. Selzer, S., Soltanoff, W., Sinai, I., Goldenberg, A., and

Bender, I.B,1968 Biologic aspects of endodontics. Part

III:Periapical tissue reaction to root canal

instrumentation. Oral Surg., Oral Med., Oral Path.

25.Hyakusoju, H, 1959 Effect of filling material on

healing of periapical tissues in treatment of human

infected root canal. Tokyo Dental Coll. Dubl. Oral

Path.

26.Muruzabel, M., Erausquin, J., and DeVoto, F.C. H. A,

1966 study of periapical overfilling in root canal

treatment in the molar of rat. Arch. Oral Biol.

103

27.Talin, S.T., and Singh. I, 1967 Sealing of root canals in

vivo conditions as assessed by radioactive iodine.

Indian Dent.

28.Seltzer, S., Soltanoff , W., Sinai, I., Smith.J,1969

Biologic aspects of endodontics. Part IV: Periapical

tissue reactions to root filled teeth whose canals had

been instrumentated short of their apices. Oral Surg.,

Oral Med., Oral Path.

29. Seltzer, S., Soltanoff, W., and Smith. J, 1973 Biologic

aspects of endodontics.V. Periapical tissue reactions to

root canal instrumentation beyond the apex and root

canal fillings short of and beyond the apex. Oral

Surg., Oral Med., oral Path.

30.Green, E. N, 1957 Microscopic investigation of root

canal files and reamers. Oral Surg., Oral Med., Oral

Path.

31.Wais, F. T,1954 Variations in the diametric

measurements of root canal files and corresponding

sizes of silver root canal points.M.S.Thesis, University

of Michigan School of Dentistry.

32. Ingle, J.I, 1955 The need for endodontic instrument

standardization. Oral Surg., Oral Med., Oral Path.

104

33. Ingle, J.I.. Levine. M, 1958 The need for uniformity of

endodontic instruments, equipment, and filling

materials. Transactions of the 2nd Internat. Conf. On

Endodont., Phila.

34.Ingle, J.I,1961 A standardized endodontic technique

utilizing newly designed instruments and filling

materials. Oral Surg., Oral Med., Oral Path.

35.Bucher, J, 1958 A preliminary investigation of the

feasibility of stainless steel files as root canal

instruments and as a root canal filling material. M.S.

Thesis, Ann Arbor, University of Michigan.

36. Heuer, M.A, 1959 A study of the Structural,

Dimensional, and physical characteristics of root

canal instruments. M. S. Thesis, Ann Arbor,

University of Michigan.

37.Craig, R. G., Peyton, F.A, 1962 Physical properties of

carbon steel root canal files and reamers. Oral Surg.,

Oral Med., Oral Peth.

38.Craig, R.G., Peyton, F.A,1963 Physical properties of

stainless steel endodontic files and reamers. Oral

Surg., Oral; Med., Oral Path.

105

39.Craig, R.G., Mellwain, E.D., Peyton, F.A, 1968

Bending and torsion properties of endodontic

instruments. Oral. Surg., Oral Path.

40.Dietz, G.C,1960 The stainless steel file for root filling

M.S. Thesis, Ann Arbor, University of Michigan.

41. Sampeck, A. J, 1961 The stainless steel endodontic

file-its use in obturation of difficult root canals. M. S.

Thesis. University of Michigan School of Dentistry.

42.Oliet, S., and Sorin, S.M, 1965 Torsional tester for

root canal instruments. Oral Surg., Oral Med., Oral

Path.

43.Oliet, S., and Sorin, S.M, 1973 Cutting efficiency of

endodontic reamers. Oral Surg., Oral Med., Oral

Path.

44.Guiterrez, J.H., Garcia. J, 1968 Microscopie and

macroscopie investigation on results of mechanical

preparations of root canals. Oral Surg., Oral Med.,

Oral Path.

45.Guiterrez, J.H., Higoux, C., Sanhueza. J, 1969

Physical and chemical deterioration of endodontic

reamers during mechanical preparation. Oral Surg.,

Oral Med., Oral Path.

106

46.Lilley, J.D., and Smith, D.C,1966 An investigation of

the fracture of root canal reamers. Brit. Dent. J.

47. Luks, S., and Bolatin, L, 1973 The myth of

standardized root canal instruments. N.Y.J. Dent.

48. Coffae, K.P., Brillint, J.D, !975 The effect of serial

preparation versus non-serial preparation on tissue

removal in the root canals of extracted mandibular

human molars. J.. Endodont.

49.Haga, C, 1967 Microcopic measurements of root canal

preparations following instrumentation. Northwestern

Univ. Dental Sch., Dent. Res. Grad. Study Bul.

50. Jungmann, C. L., Uchin, A. A., and Bucher, J.F, 1975

Effect of instrumentation on the shape of the root

canal. J. Endodont.

51.Nicholls, E, 1962 The efficacy of cleansing root

canals.Brit.Dent.J.

52. Schnieder, S.W, 1971 A comparison of canal

preparation in straight and curved root canals. Oral

Surg., Oral Med., Oral Path.

53. Shoji, Y,1965 Studies on the mechanism of the

mechanical enlargement of root canals. Nihon Univ.

School Dent. J.

107

54. Vessey, R. A, 1969 The effect of filling versus reaming

on the shape of the prepared root canal. Oral Surg.,

Oral Med., Oral Path.

55.Weine, F. S., Healy, H. J., Gerstein, H., and

Evanson.L, 1970 Pre-curved files and instrumentation

for root canal enlargement. Canad Dent. A.J.

56.Davis, S. R., Brayton, S.M., Goldman, M, 1972 The

morphology of the prepared root canal: A study

utilizing injectable silicone. Oral Surg., Oral Med.,

Oral Path.

57.Wine, F.S., Kelly, R. F., and Lio, P. J, 1975 The effect

of preparation procedures on original canal shape and

on apical foramen shape. J. Endodont.

58.Mizsaki, S.J., Tucker, J.W., and Seltzer, S, 1975 A

scanning electron microscope study of the efficacy of

various endodontic instruments. J. Endodont.

59.Arzt, A.H, 1972 Technic to help general practitioner

treat curved canals in posterior teeth. Dent. Surv.

60.Frank, A.L, 1967 An evaluation of the giromatic

endodontic handpiece. Oral Srug., Oral Med., Oral

Path.

108

61.Harty, F. J., Stock, C.J.R, 1974 The giromatic system

compared with hand instrumentation in endodontics.

Brit. Dent.

62.Harty, F. J., Stock, C.J.R, 1974 A comparison of the

flexibility of giromatic and hand operated instruments

in endodontics . Brit. Endodont. Soc. J.

63.Laws, A.J, 1968 Preparation of root canal-an

evaluation of mechanical aids. N. Z. Dent.J.

64.Molven, O, 1968 Engine and hand operated root canal

exploration. Odont. Tidskr.

65.Molven, O, 1970 Acomparison of the dentin removing

ability of five root canal instruments. Scand. J. Dent.

66. O’ Connell, D. T., and Brayton, S.M, 1975 Evaluation

of root canal preparation with two automated

endodontic handpieces . Oral surg., Oral Med., Oral

Path.

67.Richman, M.J, 1957 The use of ultrasonics in root

canal therapy and root resection. J. Dent.Med.

68. Sargenti, A, 1973 The Engine-driven canal

preparation. Anglo-Continent Dent. Soc

109

69.Sargenti, A. G. Engine powered canal preparation:

Addendum to Sargenti endodontic Education Service,

Fullerton,Ca.

70.Curson, I, 1966 Endodontic techniques. Preparation

of root canals. Brit. Dent.J.

71. Heuer, M. A, 1963 The biomechanics of endodontic

therapy. Dent. Clin. N.

72.Luks.S, 1959 An analysis of root canal instruments.

Am. Dent.

73.Sampeck. A.J, 1967 Instruments of endodontics, their

manufacture, use and abuse. Dent.

74.Schilder. H, 1974 Cleansing and shaping the root

canal. Dent.

75.American National Standards Institute. Report of

meeting of ISO/TC 106, Dentistry, London.

76.Fromme, H.G., Reidel, H, 1972 Treatment of dental

root canals and the marginal contact between filling

material and tooth, Studied by SEM, Brit.

77.Sargeant, J.E., and Stemler. J, 1964 Torsional

properties of endodontic instruments. Internat.A.

Dent.

110

78.Chernicle , L. B., Jacobs, J. J., Lautenschlager, E. P.,

and Heuer. M. A, 1976 Torsional failure of endodontic

files. J. Endodont.

79. Nyborg, H., and Halling , A, 1963 Amputation

instruments for partial pulpal extirpation. II. A

comparison between the efficiency of the Antaeos root

canal reamer and the Hedstrom file with cut tip.

Odont. Tidskr.

80.Standards Association of Australia. Draft Australian

Standard Specification for Dental Root Canal Files

and Reamers, 1972-1973.

81.Harty, F.J., Sondoozi, A. E, 1972 The status of

standardized endodontic instruments. Brit. Endodont.

82.American National Standards Institute. Proposed

ADA Specification for Root Canal Files and Reamers.

Seventh Draft as Amended. 1973.

83.Best. E.J., et al, 1960 Anew method of tooth length

determination for endodontic practice. Dent.

84.Bramante, C. M., Berbert.A, 1974 A critical

evaluation of some methods of determining root canal

length. Oral Surg., Oral Med., Oral Path.

111

85. Bregman , R.C, 1950 A mathematical method of

determining the length of a tooth for canal treatment

and filling . Canad. Dent.

86. Guldenor, P., Imobersteg, C, 1972 New method of

measuring the exact length of root canal instruments

Brit. Endodont.

87. Inoue, N, 1973 An audiometric method of determining

the length of root canals. Canad. Dent. A. J.

88.Michanowicz. A.E, 1961 A method of determining the

length of a tooth during endodontic procedures .

Dent.J.

89. Sunada. I, 1962 New method for measuring the length

of the root canal.J .Dent.

90.Vande Voorde, H. E., and Bjorndal,A.M, 1969

Estimating endodontic “working length” with

paralleling radiographs. Oral Surg., Oral Med., Oral

Path.

91. Blank, L. W., Tenca, J. I., Pelleau, G. B., Jr.

Reliability of electronic measuring devices in

endodontic therapy. J. Endodont.

92.Cash, P. W,1972 Electronics in endodontics- a clinical

report on the endometer . Tex Dent.

112

93.Cash, P. W, 1972 Electronic measurement of root

canals. Dent. Surv.

94.Cash, P. W, 1973 Electronics and root canals. J. Acad.

Gen. Dent.

95.Inoue, N, 1972 Dental “Stethoscope” measures root

canal. Dent.

96.O’Neill, L. J, 1974 A clinical evaluation of electronic

root canal measurement. Oral Surg., Oral Med., Oral

Path.

97. Seidberg, B. H., Alibrandi, B. V., Fine, H., and Logue.

B, 1975 Clinical investigation of measuring working

lengths of root canals with an electronic device and

with digitaltactile sense. Am. Dent.

98. Saunders, M, 1970 Length control of root canal

instruments. An improved system. Br. Dent.

99.Grossman, L. I., Meiman, B. W, 1941 Solution of pulp

tissue by chemical agents. Am. Dent.

100.Grossman, L. T, 1943 Irrigation of root canals. Am.

Dent.

101.Auerbach, M. B, 1953 Antibiotics vs.

Instrumentation in endodontics . N.Y.S.Dent.

113

102.Grossman, L. T, 1953 Antibiotics vs.

Instrumentation-A reply. N.Y.S. Dent.

103.Lewis, P. Sodium hypochlorite root canal therapy.

Fla. Dent.

104.Stewart, G. C, 1955 Importance of chemico-

mechanical preparation of root canals. Oral Surg.,

oral Med., Oral Path.

105.Ingle, I.L., Zeldow, B. J, 1958 An evaluation of

mechanical instrumentation and the negative culture

in endodontic therapy. Am. Dent.

106.Marshall, F. J., Massler, M., and Dute, H. L, 1960

Effects of endodontic treatments on permeability of

root dentine. Oral Surg., Oral Med., Oral Path.

107.Grahnen.H, 1963 The effect of instrumentation and

flushing of non-vital teeth in endodontic therapy II. A

clinical and radiographic follow-up. Odont.

108.Grahnen, H., Krasse, B, 1963 The effect of

instrumentation and flushing of non-vital teeth in

endodontics.Odont.

109.Masterton, J.B, 1955 Chemical debridement in the

treatment of infected pulpless teeth and chronic

periapical absess. Dent.

114

110.Shih, M., Marshall, F. J., and Rosen, S, 1970

Bacterial efficiency of sodium hypochlorite as an

endodontic irrigant. Oral Surg., Oral Med., Oral

Path.

111.Nygaard-O stby, B, 1956 Chelation in root canal

therapy. EDTA for cleansing and widening of root

canals. Odont.

112.Patterson. S, 1963 In vivo and in vitro studies of the

effect of disodium salt of EDTA on human dentin and

its endodontic implications. Oral Surg., Oral Med.,

Oral Path.

113.Weinreb, M.M., and Meier.E, 1965 The relative effect

of EDTA, sulphuric acid, and mechanical

instrumentation in the enlargement of root canals.

Oral Surg., Oral Med., Oral Path.

114.Gurney, B.F, 1967 Chelating agents. Dent.

115.Nicholson, R., Stack, M. M., Nguyen, N., and Scott.

H,1968 autoradiographic tracings utilizing Ca45 label

EDTA. Oral surg., Oral Med., Oral Path.

116.Stewart, G. C., Kapsimalis, P., and Rapaport, H,

1969 EDTA and urea peroxide for root canal

preparation. Am. Dent.

115

117.Cohen, S., Stewart, G. C., Laster, L.L, 1970 The

effects of acid, alkalis, and chelating agents on dentine

permeability. Oral Surg., Oral Med., Oral Path.

118.Zeldow, L.L ,1973 More effective methods of locating

and preparing posterior canals N. Y. S. Dent.

119.Seidberg, B.H., and Schilder, H, 1974 An evaluation

of EDTA in endodontics Oral Surg., Oral Med., Oral

Path.

120.Fraser, J. G, 1974 Chelating agents: their softening

effect on root canal dentin. Oral Surg., Oral Med.,

Oral Path.

121.Loel, D. A, 1975 Use of acid cleanser in endodontic

therapy. Am Dent.

122.Martin, H, 1975 Quantitative bactericidal

effectiveness of an old and new endodontic irrigant. J.

Endodont.

123.McComb, D., and Smith, D.C,1975 A preliminary

scanning electron microscope study of root canals

after endodontic procedures. J. Endodont.

124.Baker, N.A., Eleazer, P.D., Averbach, R.E., and

Seltzer.S,1975 Scanning electron microscope study of

116

the efficacy of various irrigation solution. J.

Endodont.

125.Senia, E. S., Marshall, F. J., and Rosen. S, 1971 The

solvent action of sodium hypochlorite on pulp tissue of

extracted teeth. Oral Surg., Oral Med., Oral Path.

126.Vande Visse, J. E., and Billiant, J. D, 1975 Effect of

irrigation on the production of extruded material at

the root apex during instrumentation. J. Endodont.

127.Goodlin, I. F, 1973 An endodontic suction adapter

kit. Canad. Dent.

128.Kahn, H., Zelikow, R., Ritchie, G., Smulson, M. H.,

and Weine, F. S, 1973 An improved endodontic

irrigation technique. Oral Surg., Oral Med., Oral

Path.

129.Malmin. O, 1973 Endovage the safer one. Endovage

Co. Akron, Ohip.

130.Becker, G.L., Cohen, S., Borer. R, 1974 The

sequellace accidently injecting sodium hypochlorite

beyond the root apex. Oral Surg., Oral Med., Oral

Path.

131.Bhat, K. S, 1974 Tissue emphysema caused by

hydrogen peroxide. Oral Surg., Oral Med., Oral Path.

117

132.Harris, W. E, 1971 Unsual endodontic complication:

Report of a case. Am. Dent.

133.Rickles, N.H., and Joshi, B.A, 1963 Death from air

embolism during root canal therapy. Am. Dent.

134.Ireland, J. F., Dolce, J. L, 1975 Modification of

technique for injection obturation. J. Endodont.

135.Greenberg. M, 1961 Filling root canals of deciduous

teeth by an injection technique. Dent.

136.Greenberg. M, 1963 Filling root canals by an

injection technique. Dent.

137.Berk, H., Krakow. A, 1965 Efficient endodontic

procedures with the use of the pressure syringe. Dent.

138.Gaum, S.T, 1970 Endodontic pressure syringe.

Dalhouse Dent.

139.Price, W. A,1918 A Report of laboratory

investigations on the physical properties of root filling

materials and the efficiency of root fillings for

blocking from sterile tooth structures. J. Nat. Dent.

140.Buchbinder. M, 1931 Nonshrinking root canal

materials. Dental Cosmos LXXIII.

141.Dixon, C. M., Rickert. U. G, 1933 Tissue tolerance to

foreign materials. Am. Dent.

118

142.Dixon, C. M., Rickert, U. G, 1938 Histologic

verification of results of root canal therapy in

experimental animals. Am. Dent.

143.Boulger, E. P, 1933 Foreign body reaction of rat tissue

and human tissue to gutta percha. Am. Dent.

144.McElory, D. L, 1955 Physical properties of root canal

filling materials. Am. Dent.

145.Higginbotham, T. L, 1967 A comparative study of the

physical properties of five commonly used root canal

sealers. Oral Surg., Oral Med., Oral Path.

146.Messing, J.J, 1969 Precision apical silver cones. Brit.

Endodont.

147.Mayne, J. R., Shapiro. S., and Abramson, I. I,1971

An evaluation of standardized gutta percha points.

Oral Surg., Oral Med., Oral path.

148.Dow, P. R., Ingle, J. I, 1955 Isotope determination of

root canal failure. Oral surg., Oral Med., Oral Path.

149.Stewart, G. C,1958 Comparative study of three root

canal sealing agents. Oral Surg., Oral Med., oral Path.

150.Marshall, F. J., and massler. M, 1961 The sealing of

pulpless teeth evaluated with radio isotopes. J. Dent.

119

151.Kapsimalis, P., and Evans, R,1966 Sealing properties

of endodontic filling materials using radioactive polar

and nonpolar isotopes. Oral Surg., oral Med., Oral

Path.

152.Antoniazzi, J. H., Mjor, I. A. Nygaard-O sty. B, 1968

Assessment of the sealing properties of root filling

materials. Odont.

153.Messing, J. J, 1970 An investigation of the sealing

properties of some root filling materials. Brit.

Endodont.

154.Blair, H. A, 1972 Evaluation of sealing properties of

endodontic filling materials and technics. A

preliminary. Ky. Dent.

155.Grieve, A.R, 1972 Sealing properties of cements used

in root filling. Brit .Dent.

156.Grieve, A. R., Parkholm, J. D. O, 1973 The sealing

properties of root canal filling cements. Further

studies. Brit. Dent.

157.Sanders, S. H., and Dooley, R.J, 1974 A comparative

evaluation of polycarboxylate cement as a root canal

sealer utilizing roughened and nonroughened silver

points. Oral Surg., Oral Med., Oral Path.

120

158.Barry, G. N., Fried, I. L, 1975 Sealing quality of two

polycarboxylate cements used as root canal sealers. J.

Endodont.

159.Wollard, R. R., Brough, S. O., Maggio, J., and

Seltzer. S, 1976 Scanning electron microscope

examination of root canal filling materials. J.

Endodont.

160.Friedman, C. E, 1973 The chemical composition and

mechanical properties of gutta percha endodontic

filling materials. M. S. Thesis, Chicago, Loyola

University.

161.Dolansky, B. H, 1973 Clinically pertinent physical

properties of gutta percha. M. S. Thesis, Chicago,

Northwestern University.

162.Goodman, A. Schilder, H., Aldrich, W,1974 The

thermomechanical properties of gutta percha. II.

Thhe history and molecular chemistry of gutta

percha. Oral Surh., Oral Med., Oral Path.

163.Schilder, H., Goodman, A., and Aldrich, W, 1974 The

thermomechanical properties of gutta percha. III.

Determination of phase transition temperatures for

gutta percha. Oral. Surg., Oral Med., Oral Path.

121

164.Schilder, H., Goodman, A., and Aldrich.W, 1974 The

thermochemical properties of gutta percha. I. The

compressibility of gutta percha. Oral Surg., Oral

Med., oral Path.

165.Gurney, B. F., Best, E. J., Gervasio, G, 1971 Physical

measurements on gutta percha. Oral Surg., oral Med.,

Oral Path.

166.Marlin, J., and Schilder, H, 1973 Physical properties

of gutta percha when subjected to heat and vertical

condensation. Oral Surg., Oral Med., Oral Path.

167.Goldman, M, 1975 Evaluation of two filling methods

for root canalc. J. Endodont.

168.Tayler, R. L., Marshall, S. J., Heur, M. A., and

Greener, E. H,1975 Characterization of endodontic

silver points. Internat. A. Dent.

169.Tayler, R. L., Marshall, S. J., Heuer, M. A., and

Greener, E.h, 1975 Anodic polarization of endodontic

silver points. Internat. A. Dent.

170.Bralton, S.M., Davis, S.R., Goldman,M,1973 Gutta

percha root canal fillings. An in vitro analysis. Part I.

Oral Surg., Oral Med., Oral Path.

122

171.Laneland. K, 1974 Root canal sealants and pastes.

Dent.

172.Barry, G.N., Heyman, R. A., Fried, I.L, 1975 Sealing

quality of instruments cemented in root canals with

polycarboxylate cements. J. Endodont.

173.Grossman, L.T, 1958 An improved root canal

cement. Am. Dent.

174.Copeland, H. I., Brauer, G. M., Forziati . A, 1955 The

setting mechanism of zinc oxide and eugenol mixtures.

J. Dent.

175.Norman, R. D., Phillips, R. W., Swartz, M. L., and

Frankiewics. T, 1964 The effect of particle size on the

physical properties of zinc oxide eugenol mixtures. J.

Dent.

176.Smith, D. C, 1958 The setting of zinc oxide-eugenol

mixtures. Br. Dent.

177.Biven, G. M., Bapna, R. J., Heuer, M. A, 1972 Effect

of eugenol and eugenol containing root canal sealers

on the microhardness of human dentin. J. Dent.

178.Bjordal, M. A, 1960 A critique of new and improved

materials for root canal filling. Lowa. Dent.

123

179.Keresztesi, K., and Kellner. G, 1966 The biological

effect of root filling materials. Internat. Dent.

180.Muruzabal, M., and Erasquin, J, 1966 response of

periapical tissues in the ratmolar to root canal fillings

with Diaket and AH26. Oral Surg., Oral Med., Oral

Path.

181.Sugiyama. F, 1944 Clinical evaluation of CA(OH)2 as

a root canal filling material. Shikwa Gakuho.

182.Laws, A.J, 1962 Calcium hydroxide as a possible root

filling material. N. Z. Dent.

183.Isomendi, F. A, 1967 Etude comparative des cements

de Rickert et de Grossman . Rev. Franc.

Odontostomat.

184.Weiner, B. H., and Schilder, H, 1971 A comparative

study of important physical properties of various root

canal sealers.I . Evaluation of setting times. Oral

Surg., Oral Med., Oral Path.

185.Weiner, B. H., and Schilder, H, 1971 A comparative

study of important physical properties of various root

canal sealers. II. Evaluation of dimensional changes.

Oral Surg., Oral Med., Oral Path.

124

186.Weisman, M. I, 1970 A study of the flow rate of ten

root canal sealers. Oral Surg., Oral Med., Oral Path.

187.Rappaport, H. M., lilly, G. E., and kapsimalis, P,

1964 Toxicity of endodontic filling materials. Oral

Surg., Oral Med., Oral path.

188.Guttuso, J, 1963 Histopathologic study of rat

connective tissue response to endodontic materials.

Oral Surg., Oral Med., Oral Path.

189.Curson, I., Kirke, E.E, 1968 An assessment of root

canal sealing cements. Oral Surg., Oral Med., Oral

Path.

190.Spanberg, L, 1969 Biological effects of root canal

filling materials. Odont.

191.Hunter , H. A, 1957 The effect of gutta percha, silver

points, and Rickerts root canal sealer on bone healing.

Canad. Dent.

192.Mitchell, D. F, 1959 The irritation qualities of dental

materials. Am. Dent.

193.Feld, G., Nyborg. H, 1962 Tissue reactions to root

filling materials I. Comparison between gutta percha

and silver amalgam implanted in rabbit. Odont.

125

194.Feldman, G., Nyborg, H, 1964 Tissue reactions to

filling materials II. A comparison of implants of silver

and root filling material AH 26 in rabbits. Odont.

195.Feldman, G., Nyborg, H., Conrado, C.A, 1967 Tissue

reactions to root filling materials III. A comparison

between implants of root filling material N2 and silver

in jaws of rabbits. Odont.

196.Matsui, A. Buonocore, M., Sayegh, F., and Yamahi.

M, 1967 Reactions to implants of conventional and

new dental restorative materials. J. Dent.

197.Flandwers. D. H., James, G. A., Burch, B., Dockum.

N, 1975 Comparative histopathologic study of nine

free amalgam and cavit in connective tissue of the rat.

J. Endodont.

198.Friend, L. A., Browne, R. M, 1968 Tissue reactions to

some root filling materials. Brit. Dent.

199.Friend, L. A., Browne, R. M, 1969 Tissue reactions to

some root canal filling materials in the bone of

rabbits. Arch ORAL Biol.

200.Langeland, K., Guttuso, J., Langeland, I.K., and

Tobon. G, 1969 Methods in the study of biologic

126

responses to endodontic materials. Tissue response to

N2 . Oral surg., Oral Med., Oral Path.

201.Spangberg, L, 1969 Biological effects of root canal

filling materials. Odont.

202.Roydhouse, R. H, 1968 Implant testing of

polymerizing materials. J. Biomed. Mater.

203.Bhat, K. S., Balvekar, S, 1975 Response of

subcutaneous connective tissue to materials and

drugs: a simplified technic. J. Endodont.

204.Rowe, A. H. R, 1967 Effect of root filling materials on

the periapical tissues. Br. Dent.

205.Erausquin, J., Muruzabal. M, 1967 Root canal filling

with ZnOE cement in the rat molar. Oral Surg., oral

med., Oral Path.

206.Erausquin, J., Muruzabal. M, 1968 Tissue reaction to

root canal cements in the rat molar. Oral Surg., Oral

med., Oral path.

207.Erausquin, J., Muruzabal. M, 1968 Periapical tissue

response to root canal cements with the addition of

acrylic spherules. Oral Surg., Oral Med., Oral Path.

127

208.Erausquin, J, 1970 Periapical tissue reaction to root

canal fillings with zinc, titanium, lead, and aluminium

oxides. Oral Surg., Oral Med., Oral Path.

209.Bhaskar, S. N. Rappaport, H.M, 1971 Histologic

evaluation of endodontic procedures in dogs. Oral

Surg., Oral Med., Oral Path.

210.Barker, B.C. W., Lochett, B.C,1972 Periapical

response to N2 and other paraformaldehyde

compounds confined within or extruded beyond the

apices of dog root canals. Dent.

211.Marcotte, L. R., Dowson, J., and Rose, N. H, 1975

Apical healing with retrofilling materials amalgam

and gutta percha. J. Endodont.

212.Rising, D.W., Goldman, M., and Brayton, s. M, 1975

Histologic appraisal of three experimental root canal

filling materials. J. Endodont.

213.Brynolf, I, 1967 A histological and roentgenological

study of the periapical region of human incisors.

Odont.

214.Moodnik, R. N., levey, M. H., Besin, M. A., and

Borden, B.G,1975 Retrogade amalgam filling: a

scanning electron microscope study. J.Endodont.

128

215.Spangberg, L,1969 Biological effects of root canal

filling materials. 7. Reaction of bony tissue to

implanted root canal filling material in Guinea pigs.

Odont.

216.Spangberg, L, 1973 Kinetic and quantitative

evaluation of material cytotoxicity in vitro. Oral

Surg., Oral Med., Oral Path.

217.Seltzer, S., Green, D. B., Weiner, N., and De Renzis,

F, 1972 A scanning electron microscope examination

of silver cones removed from endodontically treated

teeth. Oral Surg., Oral Med., Oral Path.

218.Besner, E, 1973 The use of silver points should be

discouraged . va. Dent.

219.Brady, J. M., del Rio, C.E, 1975 Corrosion of

endodontic silver cones in humans: a scanning

electron microscope and x-ray microscope microprobe

study. J. Endodont.

220.Taylor, R. L, 1975 Physical and clinical properties of

selected endodontic silver points. M. S. Thesis,

Chicago, Northwestern University.

221.Spangberg, L., and Langland, K, 1973 Biologic

effects of dental materials. 1. Toxicity of root canal

129

filling materials on Hel a cells in vitro. Oral Surg.,

Oral Med., Oral Path.

222.S-Gravenmade, E. J, 1975 Some biochemical

considerations of fixation in endodontics. J. Endodont.

223.Nicholls, E, 1963 Resorbable canal fillings, including

N2 Trans. 3rd Internat. Conf. Endodont.

224.Oswald, R. J., and Cohn, S.A, 1975 Systemic

distribution of lead from root canal fillings.

J.endodont.

225. Department of Health, 1976 Education and Welfare.

Food and Drug Administration Docket .

226.Crane, D., Moser., J. B., Kaminski, E. J., Marshall, G.

W., Sharmer, B., Greener, E. H, 1975 Biological and

physical properties of an experimental noneugenol

endodontic sealer. Internat. A. Dent.

227.Grossman, L. I, 1963 Present status of plastic root

canal filling materials. Trans. 3rd Internat. Conf.

Endodont.

228.Buoncore. M, 1963 Discussion of Present status of

plastic root canal filling materials. Trans. 3rd Internat.

Conf. Endodont.

130

229.Yee, F. S., Lugassy, A,. A., and Peterson, J. N, 1975

Filling of root canals with adhesive materials. J.

Endodont.

230.Yoemans, J. D., and Urist, M.R, 1967 Bpne induction

by decalcified dentin implanted into oral, osseous, and

muscle tissue. Arch. Oral Biol.

231.Nygaard-O stby, 1971 Introduction to endodontics,

Universitetsforlaget, Oslo.

131