CLASSIFICATION OF SKELETAL AND DENTAL MALOCCLUSION: REVISITED
Figure 1. Skeletal classification
( skeletal III type 3), which gives detailed explanation aiding in diagnosis and treatment planning.( Fig. 1)
4.2. Occlusal Classification: revisited The BSI and Katz’ s classification deal with the partial description of the malocclusion. The British system of classification related to the anterior teeth where it needs further elaboration while Katz’ s system focuses on the premolar occlusion and ignore the canines and molar classification. Snyder and Jerrold( 2007), have concluded that a modification of Angle’ s system that is more descriptive is needed, after they have sent an e-mail survey to the department chair or the program director of every orthodontic program in the United States, Canada, and Puerto Rico( n = 80). The survey included photos of models placed into ¼ cusp, ½ cusp, and ¾ cusp distal occlusions, and the participants were asked to classify them by selecting from a list of terms or writing one of their own. They were also asked whether they thought that the Angle molar classification was adequate for communication and diagnosis. Fourty surveys were completed and returned. The results showed a variety of terminology being taught, and most educators do not use Angle’ s classification as he defined it. About half of the respondents were dissatisfied with the Angle molar classification system 17. In 2002 Siegel conducted 57 surveys which were mailed to department chairs in the United States, asking them to identify the definition to which their orthodontic residency program subscribes; 34 questionnaires were returned.
Twenty-two responses supported the notion that subdivision refers to the Class II side, 8 responses said that it refers to the Class I side, 3 responses supported neither view, and 1 response indicated that in the program not everyone could agree on the meaning of subdivision. Although the prevailing belief appears to be that subdivision indicates the side with a molar malocclusion, the orthodontic community does not have a consistent standard, and it is time to resolve this controversy 18. Due to the low reliability of the Angle method, a reconsideration is needed to develop the older classification. The reconsideration is done in the antero-posterior and on both sides, where molar classification is more elaborated. In this revision class IV, V and VI are generated which helped in treatment planning and suggesting treatment protocol. Skeletal Class III malocclusion was strongly differentiated from the other sagittal classes, specifically in the mandible, as calculated through Björk and Jarabak analysis 19. A review article emphasizes the need to identify genetic and environmental factors that cause or contribute risk to skeletal malocclusion and the possible association with other medical conditions to improve assessment, prognosis and therapeutic approaches 20. Accurate and detailed classification is always needed to drive an accurate diagnosis and treatment plan. The author followed the BSI incisor classification with modifications for class II and III, accepts canine classification and modifies molar classification, which are further elaborated for the ease of diagnosis and accuracy of treatment planning in orthodontics. 4.3. Incisor’ s Classification( Fig. 2) Class I: When the mandibular incisor edges lie or are below the cingulum plateau of the maxillary incisor( BSI, 1983), the overjet is 2-4 mm. Class II: When the mandibular incisors edges lie posterior to the cingulum plateau of the maxillary incisors( BSI, 1983). It could be:
• Class II / 1: Proclined maxillary incisors with overjet more than 4 mm.
• Class II / 2a: Retroclined maxillary centrals and proclined laterals, or both central and lateral incisors are retroclined with normal or reduced overjet.
• Class II / 2b: Retroclined maxillary centrals and proclined laterals, or both central and lateral incisors are retroclined but with increased overjet. Class III: When the mandibular incisors edges lie anterior to the cingulum plateau of the maxillary incisors( BSI, 1983).
• Class III type 1: Positive overjet but less than 2 mm.
• Class III type 2: Edge to edge incisors relationship.
• Class III type 3a: Negative overjet.
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