CLASSIFICATION OF SKELETAL AND DENTAL MALOCCLUSION: REVISITED
the primary teeth, in addition did not classify the skeletal relationship and did not predict the etiological factors, so revisiting was always needed. In 1915 Deway’ s modified Angle’ s Class I and III malocclusion by segregating malposition of anterior and posterior segments, CL I: type 1( Crowding of Max anterior teeth); type 2( Proclined Max incisors); type 3( Max incisors are in crossbite); type 4( Posterior cross-bite); type 5( Mesial drift of molars). CL II( no modifications). CL III: type 1:( Edge to edge bite), type 2:( Crowded Mandibular incisors and lingual to Max incisors); type 3:( Underdeveloped crowded Maxillary arch and a well developed Mandibular arch) 4. Lischer in 1933 further modified Angle’ s classification by giving substitute names; CL I( Neutrocclusion); CL II( Distocclusion); CL III( Mesiocclusion). He also proposed terms to designate individual tooth malposition, Mesio-version( Mesial to normal position); Disto-version( Distal to normal position); Linguo-version( Crossbite); Labio-version( Increased OJ); Infra-version( Submerged tooth); Supra-version( Super-erupted); Axio-version( Tipped tooth); Torsiversion( Rotated tooth); Trans-version( Transposed tooth) 5.
3. Results Ackerman and Proffit( 1969) introduced a very comprehensive system of classification using the Venn diagram. The classification considered five characteristics and their inter-relationships were assessed, namely: alignment, profile, transverse, class and overbite 6. Angle’ s classification still seems to be the most popular tool for classification of malocclusion, despite its well-known disadvantages 7. Hans et al.,( 1994), noted the inadequacy of Angle’ s classification when they were unable to classify approximately 7 % of a large sample( n = 4309) of models in the Broadbent-Bolton study 8. Another study conducted by Baumrind et al.,( 1996) on whether to extract in orthodontic treatment, found that 28-33 % disagreement among the 5 participating orthodontist 9. Katz( 1992a) showed an inter-examiner disagreement of 49 % among 270 orthodontists using Angle’ s classification 10. The percentage agreement of Katz’ s technique proved superior to that of the classical Angle’ s classification 11, 12. Rinchuse found Angle’ s classification to be limited because it is a system of discrete classes as compared to continuous transition of maxillomandibular dental arches in the sagittal plane 13. The British Standard Institute( BSI) classified dental malocclusion in 1983 according to the maxillary and mandibular incisors relationship. Class I: When the mandibular incisor edges lie or are below the cingulum plateau of the maxillary incisors. Class II: When the mandibular incisor edges lie posterior to the cingulum plateau of the maxillary incisors, the maxillary incisors could be proclined where it is classified as Class II / 1, or retroclined maxillary centrals and proclined laterals, or both central and lateral incisors are retroclined where it is grouped under Class II / 2. Class III: where the mandibular incisor edges lie anterior to the cingulum plateau of the maxillary central incisors 14. The BSI classification was more accurate in grouping the malocclusion 15. The British method of overjet and overbite assessment 15 and the quantitative technique proposed by Katz( 1992b) 16 developed over the years, proved to be more amenable to reproduction than Angle’ s classification 11, 15. In the Du et al. study( 1998) in their study where four orthodontic faculty members at one dental school classified 25 dental casts according to the classification systems of Angle, Katz, and the British Incisor Classification 11. The dental casts were selected from a pool of 350 pretreatment graduate orthodontic cases and were those deemed the most atypical. The results demonstrated that Katz’ s classification was more reliable than both the Angle and the British one. Angle’ s classification was the least reliable of the three methods.
4. Discusion 4.1. Skeletal classification: revisited In the author’ s view orthodontic skeletal classification could be grouped into class I( straight), class II( convex) and class III( concave). Salzmann’ s classification did not specify that the problem is due to maxillary protrusion, mandibular retrusion or a combination of both. The same is true for the concave profile, his method did not specify that the problem is due to maxillary retrusion, mandibular protrusion or a combination of both. The author agrees with all scholars that skeletal class I has a straight profile( Fig. 1), which explains homogeneous relationship between the maxilla and mandible, or in another terms they grow in unison. In cases of Skeletal I the problem is dental malrelationships. It is present in two planes, the vertical and the transverse planes where the anteroposterior plane is normal or within average. There is always a question which arises in cases where it is straight to mild convexity or mild concavity. The author’ s view is to enlarge the description of skeletal I so as to include the mild convexity and mild concavity as far as it is confirmed by the ANB angle. The range of skeletal I would be straight to mild convexity or mild concavity. Salzmann’ s Skeletal II( convex profile) did not indicate either whether it is due to protruded maxilla or retruded mandible or a combination of both. In the present study, Skeletal II could be of three types; type 1( retruded mandible), type 2( protruded maxilla) and type 3( combination of both).( Fig. 1) The same applies for Class III( concave profile), again Salzmann did not specify either whether it is due to maxillary retrusion or mandibular protrusion. According to my explanation it could be due to maxillary retrusion( Skeletal III type 1), or mandibular protrusion( Skeletal II type 2), or a combination of both
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