MANAGEMENT OF CLASS II DIVISION 2 MALOCCLUSION AN INSIGHT

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1 MANAGEMENT OF CLASS II DIVISION 2 MALOCCLUSION AN INSIGHT Dr. C.S. Ramachandra Author: Prof. Dr. C.S. Ramachandra Diplomat Indian Board of Orthodontics Professor & Head Dept. of Orthodontics, Principal, AECS Maaruti Dental College & Research Center, Bangalore. Abstract : Class II Div 2 malocclusion has been a challenging clinical entity in terms of treatment and more so in terms of stability of the result. When one browses through the literature, a lot is documented on the etiology and treatment approach. This article tries to compile such information and present cases treated by infusing them in to the treatment regime. Intrusion and Torqueing of incisors, reduction of inter incisal angle and non extraction approach to improve lip support could be some of the factors leading to successful outcome. Key Words : Inter incisal angle, Deep bite, Lip line, Centroid and class II division 2. INTRODUCTION Class II div2 malocclusion is characterized by the manifestation of a group of features which make it qualified to be termed as a syndrome. The following are the characteristics to reckon with: Increased lower lip pressure on the upper incisors and increased masticatory muscle forces 2 Deep bite, retroclined maxillary centrals, proclined laterals and even morphologically different upper incisors such as thinner crowns labiolingually 3 and high collum angle 4 Class II skeletal discrepancy with counter clock wise rotation which adds to the problem of deep bite, chin prominence and reduced lower facial height. Familial occurrence of Class IIdiv2 has been documented in great deal and there is strong evidence of genetics as the main etiological factor in the development of this type of malocclusion. After evaluating 114 class II div 2 cases Markovic observed that the monozygotic twins showed 100% concordance and 90% of the dizygotic twins showed discordance 5. Certain studies point to an incontestable genetic influence probably autosomal dominant with incomplete penetration and variable expressivity. It could also possibly be explained by a polygenic model with a simultaneous expression of a number of genetically determined morphological traits rather than controlled by a single gene 1. It is possible to believe that unlike in other forms of malocclusions the incisors in class II div 2 malocclusion occupy a predetermined position which could make one think to be by a divine guidance. On the contrary the local environmental factors influence the erupting incisors, which make their behavior more predictable. Infraocclusion of buccal segment and counter clockwise rotation of the mandible leads to an excess of soft tissue in the lower face and results in an upward shift of the lip line and this influences the maxillary incisors to get retroclined which is demonstrated as in the figures 1 to 4. fig :1 fig: 2 fig:3 fig:4 Fletcher has convincingly established that the upper incisors retroclined in Class II div 2 after their emergence in to the oral cavity. The project involved a serial study of early development and tooth eruption between the ages of 4.5 to12.5 years 6. In this type of malocclusion upper central incisors could have large collum angle, which can pose problems in intrusion 76

2 and torqueing movements. Torqueing of these teeth with pronounced collum angle are likely to have their roots positioned closer to the palatal cortical plate than expected and could be a factor responsible for relapse. 4 Many clinicians hypothesize that retroclination of the maxillary central incisors in class II Div 2 malocclusion is caused by increased resting lip pressure. Lapatki et al revealed that the retroclination of maxillary central incisors are primarily due to high lip line and not due to hypertonic peri oral musculature. Higher the lip line, the lower lip exerts more pressure on the incisal half resulting in the retroclination of the maxillary incisors as demonstrated in figure 5. 7 College, Bangalore it is only 3% amongst the patients seeking treatment. Figures rang form 3% to6.4% world wide. It could be argued that people with class II division 2 malocclusion look smart and it could be one reason for their not seeking treatment. Inadequately trained doctors and poor choice of appliance could result in unstable results creating an impression among general public that this type of malocclusion is untreatable. It is challenging to treat such syndrome like entity which demands the clinician to target/treat all the features responsible so as to achieve pleasing and stable outcome. Treatment rationale: Following could be the list of our objectives, and achieving this will ensure a stable outcome. Fig: 5 1. De crowding and Aligning: This would be the priority to every one and the main force behind patient motivation. Lapatki et al have concluded that Orthodontic treatment of class II Div2 cases should include: Intrusion and torqueing of maxillary incisors, Eliminate the high pressure exerted by the lower lip on maxillary incisors and consequently reduce the post orthodontic relapse. Limitations imposed by the soft tissues enveloping the dentition were thought to be inviolable. This has inhibited the clinicians in treating class II div 2 malocclusions. Selwyn and Barnett while highlighting the significance of pressure exerted by soft tissue, have stressed on its role in evaluating the situation, determining the possibilities and limitations of the treatment. The best therapeutic approach is certainly the intrusion and torqueing of the maxillary incisors, which is the only means of eliminating the high pressure exerted by the lower lip on them. 8 Crowding associated with this type of malocclusion appears to be on the higher side and very often clinicians are tempted to advice premolar extractions. But Salzmann has categorically stated that extraction should be considered rarely. 9 Mills in a study of sixty treated cases found that over bite commonly relapses and showed that the best treatment results are obtained where there is a combined reduction in inter incisal angle and over bite(10). Incidence of class II div2 malocclusion is lowest amongst all. In our department at Maaruti Dental 2. Overbite reduction: Deep over bite results in breakdown of both hard and soft tissues. It is necessary to establish correct incisal relation to preserve the health of the oral structures. 3. Reduction in inter incisal angle to degrees : This would mutually prevent the incisors from supra erupting and there by preventing the relapse of division 2 pattern. 77

3 same which can be aided by forwardly directed forces. One should even contemplate surgical advancement of mandible in adult cases so as to achieve class 1 situation, with out which achieving correct incisal relation would be a dream. 4. Bring the centroid of the maxillary incisor lingual to the mandibular incisal tip : The maxillary centrals tend to revert back to their previous position which is typical to this malocclusion after treatment. This type of relapse could be prevented bya) Getting the mandibular anteriors bodily forward and not merely tipping. b) Torqueing the maxillary centrals enough, so as to direct the occlusal forces generated by the mandibular incisors labial to the centroid of the maxillary central incisors. 7.Retention Protocol : Preferably bonded lingual retainer for the mandibular anteriors and for the upper arch Hawley s or molded clear retainers would be advisable. CASE REPORT: 5. Support the facial profile : Positioning of incisors as directed in rationale no 3 & 4 would help in straightening the profile and eliminate the sunken face appearance and aged look. 6. Correct the buccal segment to Class I : Many a time opening the bite eliminates the restrictive effect on the mandible allowing forward shift of the The clinician can be influenced by factors such as the training availed, philosophy followed, and facility available in selecting the appliance. Three cases treated by me are presented where an effort is made to satisfy the listed objectives which are crucial in the stability of the results achieved..022 slot pre adjusted system was used for their effectiveness in establishing required torque to the maxillary incisors and induce bodily movement of mandibular anterior teeth. These patients had all the classical features of class II div2 malocclusion. The first two cases are treated with out any extractions, but the third case had an impacted mandibular canine which was removed. (Since there was Bolton s excess in the mandibular anteriors, this did not matter). Self ligating brackets were used in the maxillary arch for this case. Maxillary teeth are addressed initially and once enough clearance is achieved brackets are bonded to mandibular teeth. The arch wire sequence was similar in all these cases-started with.016 Niti. for first two months followed by 16*22 RCS Niti and progressively filling the slot up to 21*25 SS wires. Class II elastic forces are used to achieve inter arch correction. For the maxillary teeth, vacuum molded retainer and for mandibular teeth bonded lingual retainers were given. 78

4 CASE 1: Pre treatment: Progress : Finish: Measurement SNA Angle SNB Angle ANB Angle U 1 to NA dist U 1 to NA angle L 1 to NB distance L 1 to NB angle Pog to NB distance 5.4 Interincisal angle Occlusal to SN angle Go-Gn to SN angle Mechanotherapy : SNA Angle SNB Angle ANB Angle U 1 to NA dist U 1 to NA angle L 1 to NB distance L 1 to NB angle Pog to NB distance 10.0 Interincisal angle Occlusal to SN angle Go-Gn to SN angle

5 CASE 2: Pre treatment: Progress : Finish: SNA Angle SNB Angle ANB Angle U 1 to NA dist U 1 to NA angle L 1 to NB dist L 1 to NB angle Pog to NB dist 10.5 Interincisal angle Occl to SN angle Go-Gn to SN angle Mechanotherapy : SNA Angle SNB Angle ANB Angle U 1 to NA dist U 1 to NA angle L 1 to NB dist L 1 to NB angle Pog to NB dist 8.0 Interincisal angle Occl to SN angle Go-Gn to SN angle

6 CASE 3: Pre treatment: Finish: SNA Angle SNB Angle ANB Angle U 1 to NA dist U 1 to NA angle L 1 to NB dist L 1 to NB angle Pog to NB dist 3.1 Interincisal angle Occl to SN angle Go-Gn to SN angle SNA Angle SNB Angle ANB Angle U 1 to NA dist U 1 to NA angle L 1 to NB dist L 1 to NB angle Pog to NB dist 5.6 Interincisal angle Occl to SN angle Go-Gn to SN angle Mechanotherapy : 81

7 DISCUSSION: Orthodontic treatment mechanics has evolved over the time enabling operators to provide better results while treating malocclusions. It is important to ensure stability of what is achieved to claim long term success. If we attain the former and fail in the later, it mandates us to investigate in to the structural flaws which caused the relapse. Most of the clinicians would achieve the best form of finish by de crowding and aligning and partially opening the bite but may not go to the extent of looking into the reduction of inter incisal angle and bringing the centroid of maxillary incisor behind the mandibular incisal edge. Most of the time the class 2 situation gets corrected with the unlocking of the mandible aided by class 2 elastic forces, as shown in the cases presented if the treatment is undertaken during the early permanent dentition. In sever cases of inter arch discrepancy, surgical options can be considered. It is advisable to practice bonded lingual retainer in the mandibular arch and vacuum molded retainers for the maxillary teeth which can precisely hold the teeth in their corrected position. REFERENCE: 1. Mossey.P.A- The heritability of malocclusion, 1999 BJO.26, Grant. T. Mclntyre, Declan. T. Millett- Lip Shape and Position in class II div 2 malocclusion Angle Orthodontist, 76, N.R.E. Robertson, Roy Hilton- Feature of the upper central incisor in class II div Angle orthodontist 35, 51-53,. 4. Helen P. Delivanis et al- Variation in morphology of the maxillary central incisors found in class II div2 malocclusion AJO-DO, Milan D. Markovic- At the crossroads of oral facial genetics.1992 European Journal of Orthodontics Fletcher. GGT- The retroclined upper incisor. 1975, BJO Lapatki. B.G. et al, - The importance of the level of the lip line and resting lip pressure in class II div 2 malocclusion J Dent Res , 8. B.J.Selwyn-Barnett- Rationale of treatment for class II Div 2 malocclusion- 1991,BJO Salzmann.J- Practice of Orthodontics Mills J. R. E - The problem of overbite in Class II Division 2 malocclusions, BJO, 1,