Class II subdivision treatment. ( journal club presentation)

GOOD AFTERNOON

CLASS II SUBDIVISIONSAND ART

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Journal club presentation

Under the guidance of : Dr. Mohammad Mushtaq, PROFESSOR & Head

By:

Sneh Kalgotra,

2nd Year P.G.Department of Orthodontics & Dentofacial

Orthopaedics, GDC & H, Srinagar.

Class II subdivision treatment success rate withsymmetric and asymmetric extraction protocols.

Guilherme Janson,

Eduardo Alvares Dainesi, Jose Fernando

Karina Jeronimo

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About the present article

Year : 2003

Volume : 124

Page number : 257-64

Received for publication : September 2002

Accepted for publication : December 2002

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prologue

Patients with Class II subdivision malocclusions have Class I characteristics on one side and Class II characteristics on the other, primarily because of the distal positioning of the mandibular first molar in relation to the maxillary first molar on the Class II side.

In most patients with Class II subdivision malocclusion,

the maxillary dental midline is coincident tothe mid-sagittal plane, or has a minimal deviation, whereas the mandibular dental midline is usually displaced toward the Class II side.

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The possible treatment approaches include symmetric extraction of 4 premolars and asymmetric extraction of 3 premolars.The 4- premolar-extraction approach will produce a final occlusion with bilateral Class I molar and canine relationships.

On the other hand, asymmetric extraction of 3 premolars (2 maxillary premolars and 1 mandibular premolar on the Class I side) will produce Class I canine and molar relationships on the Class I side and Class II molar and Class I canine relationships on the Class II side, along with coincidence of the maxillary and mandibular dental midlines.

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Proposed alternative title

Class II subdivision treatment success rate withsymmetric and asymmetric extraction protocols in vitro study : pre- and post treatment study models comparison using Grainger’s treatment priority index.

21 words

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Material and methods

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Material and methodsThe sample was selected retrospectively from thefiles of the Orthodontic Department at Bauru Dental School.

Initial and final study models of 51 patients who initially had Class II subdivision malocclusions and were treated with fixed edgewise appliances were collected.

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Group 1 included 28 patients (11 males, 17 females) treated with 4 symmetric extractions, at an initial mean age of 13.55 years (range, 10.25 to 19.75).

Group 2 included 23 patients (10 males, 13 females) treated with 3 asymmetric extractions, at an initial mean age of 14.87 years (range, 11.66 to 17.83).

Selection criteria

A full Class II molar relationship on one side and a Class I molar relationship on the other and all permanent teeth up to the first molars.

Sample selection was based exclusively on the initial anteroposterior dental relationship, regardless of any other dentoalveolar or skeletal characteristic.

Forty nine patients had Class II Division 1 subdivision malocclusions (27 in group 1 and 22 in group 2), and 2 had Class II Division 2 subdivision malocclusions (1 in each group).

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Material and methods

A form (Fig) was used to calculate the TPIon the pretreatment and posttreatment study models of each patient. The items measured were restricted to those describing an occlusal anomaly.

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Two copies of the form (Fig) were required to calculate the TPIs of each patient.

Development of PTI

A storehouse of invaluable records, particularly for a developmental study, is available at the Burlington Orthodontic Research Centre. Sets of dental casts are on file from across-sectional sample of patients was taken.

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Material and methods

Maxillary-to-mandibular dental midline deviation,overbite, and overjet were measured before and after treatment with Mitutoyo calipers (Mitutoyo America, Aurora, Ill).

● Dental midline deviation: transversal distance betweenthe maxillary and mandibular dental midlines;● Overbite: vertical distance from the incisal edge ofthe mandibular incisor to the perpendicular projectionof the incisal edge of the maxillary incisor on the labial surface of the mandibular incisor;● Overjet: horizontal distance between the labial surfaceof the mandibular incisor and the incisal edge of the maxillary incisor.

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Material and methods

To determine the error, 30 pairs of study models

were randomly remeasured by the same examiner.

The t test for independent samples was used for normal distributions and verified by the Kolmogorov-Smirnov test (for initial and final values, as well as for the changes).

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Critical appraisal of material and methods

Authors have not considered the skeletal parameters underlying the problem as they form significant part of the treatment planning and cannot be generalized for the patients.

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Results

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ResultsThere were significant differences between the groups only for initial mean age and final midline deviation and its change during treatment.

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Discussion

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DiscussionCompatibility of the groups Because both groups were similarly chosen, it could be expected that these characteristics would be evenly distributed among them.

Extractions of either the first or second premolar was not a concern for several reasons.

a)The probability of extraction of the second premolars would be similar in both groups.

B) Previous studies have shown that resistance to mesial movement of the posterior segments is similar after extracting the first or second premolar.

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DiscussionAnother selection criterion was all permanent

teeth up to the first molars before treatment.The absence of any tooth might, in some

instances, either simplify or complicate correction of the malocclusion, and this could interfere with the results.

The 2 patients with Class II Division 2 subdivisionmalocclusion were included in the sample

becausethere was 1 for each group and also because

correction of the dentoalveolar anteroposterior discrepancy is similar in both types of Class II malocclusion

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DiscussionStudy designThe best way to evaluate initial malocclusion

severity and final occlusal outcome is a direct clinical evaluation of each patient.

However, this would be almost impossible in a retrospective study.

The first would be tracking the patients for years after treatment; many might have changed their addresses or moved to other cities.

Even if many of the patients could be found, their treatment results could be affected by relapses or dental losses.

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DiscussionThe TPI, as developed by Grainger,was

selected among other indexes:Because it allows for dental cast evaluation.The most commonly used indexes are valid for

determining treatment priorities.The TPI is particularly applicable for

comparing orthodontic treatment results.It is also a good epidemiologic indicator.TPI was applied because its reliability has

already been demonstrated.

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DiscussionTREATMENT CHANGES:The greater change in overjet is probably due

to the smaller amount of retraction of the mandibular incisors required in patients with asymmetric extractions.

There is also a greater difficulty in controlling the overbite when 4 first premolars are extracted; this might explain why the 3-premolar-extraction approach showed a tendency for a better correction of this vertical irregularity.

There was a better success rate of correcting the interdental midline deviation with asymmetric extractions.

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Discussion It would be more difficult to correct the

anteroposterior discrepancy of the posterior segments on the Class II side when 4 premolars are extracted. That is because the Class II molar relationship must be corrected by means of Class II inter maxillary elastics with extra-oral headgear, which requires intense patient compliance.

Correcting the midline deviation in this treatment is easier, because it will be achieved simultaneously with closing the extraction space in the mandibular arch, with little or no need for intermaxillary elastics for midline correction and patient compliance.

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Discussion

Correcting an interdental midline deviation is also morearduous because the mandibular midline will tend todisplace even more toward the Class II side duringclosure of the mandibular premolar extraction space. In this situation, Class II elastics on the Class II side and diagonal anterior elastics must be used to help correct the interdental midline deviation. This creates agreater dependence on patient compliance for a satisfactory result and therefore a greater risk for failure.

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DiscussionTreatment time of these extraction protocols

should also be considered. The number of extracted premolars has a direct relationship to treatment time, according to Fink and Smith. Treatment time is increased by 0.9 months for each extracted premolar.

In adult patients with Class II subdivision malocclusion, extractions would also help to

decrease these unfavorable consequences.

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Critical appraisal of discussionStrengths of this study- It is a simple study.-The sample was randomly selected to avoid biasing.-There is also minimal need for Class II and anteriordiagonal intermaxillary elastics, because the molars onthe Class II side will remain in their initial positions andthe correction of the interdental midline deviation willbe consequent to closing the mandibular extractionspace.-Less trauma to the patient.- Saving a sound tooth .

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Weakness of the study: Authors have not mentioned anything about

the clinical finding in the patient pre-treatment and post treatment.

Authors have not considered cephalomertic values for treatment planning.

Nor have the authors made any comparions of the cephalometric values pre and post treatment to give us a clear picture of the results achieved and the conclusions made.

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Nor have the authors mentioned any model analysis they used to decide for the first or second pre molar extraction.

Infact authors have failed to mention which pre molar did they extract.

Autos have failed to mention any soft tissue evaluation pre and post treatment.

Authors have also not mentioned about the direction of future research in this area.

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Conclusion

Treatment of Class II subdivision malocclusions with extraction of 3 premolars showed a tendency to a slightly better treatment success rate in correcting the maxillary-to-mandibular dental

midline deviation and consequently a tendency for aslightly better correction of the anteroposterior discrepancy of the posterior segments, compared with 4-premolar- extraction treatment.

There were no statistically significant differences in the final values of TPI, overbite, overjet, or treatment changes in these variables between the Class II subdivision groups treated with either protocol.

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Review of literature

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Nance , K.N. The removal of second pre-molars in orthodontic treatment. A.J.O 35:685-695,1949.

Another early refernce tosecond pre-molar extraction was by Nance in 1949.

He spoke of removing second pre-molar in an effort to keep the incisors over basal bone.

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Dewel, B. F, Second premolar extraction in Orthodontics : Principles, procedures and case analysis, A.J.O. 41:107,1995

In 1955 treated and reported a borderline extraction case I shich extraction of secondpremolars was utilized. He found relapse of rotations , but felt that this was less severe than would have occurred with extraction of first premolars or no extarctions.

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Schoppe, R.J. An analysis of second pre-molar extraction rocedures, Angle Orthod, 34:292-302,1964

In 1964,Schoppee wrote that since there is variation in the type and severity of orthodontic cases, there must be a variety of tretament plans and appliances . He concluded that when arch –length discrepancy is seven and a half mms or lss and thre is no need o retract the incisors, it amy be advisable to remove second rather than first pre molars

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Logan, Lee R, Second premolar extraction in class II and Class II, A.J.O 63:114-147,1973

That mandibular molars can be moved far too mesially in Class II cases with extraction of second premolars. He also stated that such extraction facilitaties closure of an open bite by reducing posterior vertical dimension

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deCastro,Newton, Second premolar extraction, A,J,O 65:115-137,1974.

He wrote that when the arch – tooth discrepancy is five milimeters or les s ina aptient with good profile, extraction of second premolars is indicated.

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Joondeph, Donald R. and Ridel, Richard A, Second premolar serial extraction A.J.O 69:169-189,1976.

The drift pattern in cases where the second premolar are absent is more favourable than the first premolar.

When lingual movement of incisors is indicated they advise extraction of first premolars.

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Williams, Raleigh and Hosila, Fred J, The effect of different extraction sites upon incisor retraction. A.J.O 69:338-410,1968

Whether diagnosis is based on the Apo line, the Steiner’s analysis, or the Tweed triangle, the position of the lower incisor is prime importance and each clinician has a concept of where he wants to put the teeth for maximum stability, esthetics and function. The amount of retarction is determined by varying the extraction site.

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Posen, A, Perioral assesment, Angle Orthod, 446:118-143,1976

In 1976 Posen, in his evaluation of the tonicity of the perioral musculature, advices extraction of second pre molars when extraction is necessary in patients with hypertonic lip muscles. His work and interest is a “pommeter”, an instrument he designed to measure lip activity, is also a typical of the swing towards soft tissue evaluation.

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Ketterhagen D.H. ,First premolar or second pre molar extraction ;Angle Orthod,49: 190-198,1979.

The combination of lips to E line and lower left central to Apo was helpful in classifying second pre molar cases.

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Extraction Choice: In the Era of Evidence Based Orthodontics

However, the superiority of first premolar over second premolar extraction is not supported by recent evidence. Second premolar extraction is in harmony with Mother Nature’s Rules. Mother Nature ruled in many instances to eliminate second premolars from the dentition

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Asymmetric extractions in orthodontics Camilo Aquino MelgaçoI; Mônica Tirre de Souza Araújo

Asymmetric extractions could simplify and facilitate orthodontic treatment and mechanics in some specific cases. As a result, first molars relationship could differ for right or left sides and this asymmetry would not bring functional or esthetics problems. In cases of Bolton discrepancy, a lower incisor extraction option should be considered. However, the orthodontist must have total control of the mechanics used to achieve the best final results at the end of the treatment.

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Cephalometric evaluation of symmetric and asymmetric extraction treatment for patients with Class II subdivision malocclusions.A JO D O July 2007

 It was concluded that the 3-premolar asymmetric extraction protocol in Class II subdivision malocclusions produces significantly less mandibular incisor and soft-tissue retraction than the 4-premolar extraction protocol.

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Smile attractiveness in patients with Class II division 1 subdivision malocclusions treated with different tooth extraction protocolsEJO; Eur J Orthod (2011)

It was concluded that smile attractiveness is similar in treatment protocols of three, and four premolar extractions and that widths of buccal and posterior corridors do not influence smile attractiveness in these groups.

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Critical reflection

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There is probably no facet of orthodontic treatment that has caused as much controversy as the decision to extract or not to extract or what to extract.

Like a pendulum the popularity of premolar extraction has swung back nad forth, between the extremes of non-extraction at any cost and rountine extractions to achieve arbitrary cephalometric norms.CLASS II SUBDIVISION

Orthodontists daily make decisions regarding the plans of treatment to be followed for their patients carefullyand exhaustingly conducting cepahlometric studies in combination with clinical evaluation and model and photographic analysis.

In spite of the wealth of material available for planing treatmnt, ulitmately decisions are related to an entity which we call “clinical judgment”.

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Bottom line: Extractions are just at a tool, not good or bad in themselves. Used right, they improve the quality of treatment, used wrong they create a poor result.

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Refrences1. Alavi DG, Begole EA, Schneider BJ. Facial and dental archasymmetries in Class II subdivision malocclusion. Am J OrthodDentofacial Orthop 1988;93:38-46.2. Rose JM, Sadowsky C, Begole EA, Moles R. Mandibularskeletal and dental asymmetry in Class II subdivision malocclusions.Am J Orthod Dentofacial Orthop 1994;105:489-95.3. Janson GRP, Metaxas A, Woodside DG, Freitas MR, Pinzan AP.Three-dimensional evaluation of skeletal and dental asymmetriesin Class II subdivision malocclusions. Am J Orthod DentofacialOrthop 2001;119:406-18.4. Cheney EA. The influence of asymmetries upon treatmentprocedures. Am J Orthod 1952;38:934-45.5. Cheney EA. Dentofacial asymmetries and their clinical significance.Am J Orthod 1961;47:814-29.6. Janson GRP, Pereira ACJ, Dainesi EA, Freitas MR. Dentalasymmetry and its implications in orthodontic treatment: a casereport. Ortodontia 1995;28:68-73.7. Todd M, Hosier M, Sheehan T, Kinser D. Asymmetric extractiontreatment of a Class II Division 1 subdivision left malocclusionwith anterior and posterior crossbites. Am J Orthod DentofacialOrthop 1999;115:410-7.

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8. Burstone CJ. Diagnosis and treatment planning of patients withasymmetries. Semin Orthod 1998;4:153-64.9. Erdogan E, Erdogan E. Asymmetric application of the Jasperjumper in the correction of midline discrepancies. J Clin Orthod1998;32:170-80.10. Gianelly AA, Paul IAA. A procedure for midline correction.Am J Orthod 1970;58:264-7.11. Herschcopf SA. Class II, division 2 malocclusion—nonextraction.Am J Orthod Dentofacial Orthop 1990;97:374-80.12. Lewis D. The deviated midline. Am J Orthod 1976;70:601-16.13. Wertz RA. Diagnosis and treatment planning of unilateral ClassII malocclusion. Angle Orthod 1975;45:85-94.14. Grainger RM. The orthodontic treatment priority index. Vitalhealth and statistics series 2, no. 25. Washington, DC: NationalCenter for Health Statistics; 1967.15. Ghafari J, Locke SA, Bentley JM. Longitudinal evaluation of thetreatment priority index (TPI). Am J Orthod Dentofacial Orthop1989;96:382-9.

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THANK YOU.-SNEH KALGOTRA, PG STUDENT

3-D ARTCLASS II SUBDIVISION