Craniofacial patterns of Japanese adults with various types of malocclusion: a counterpart analysis

Craniofacial morphological characteristics of Japanese adults with various malocclusions were investigated. Cephalometric radiographs of 100 Class I, 100 Class II, and 100 Class III cases were selected and subjected to counterpart analysis as described by Enlow. Results of individuals with normal Class I occlusion revealed a mean value of 39.5 degrees for the angle of the middle cranial fossa relative to the posterior maxillary plane alignment (MCF/PM). This value was used as the basis for intrinsic alignment comparisons for all other skull points. Class I and II malocclusions were classified as either type A or B, depending on whether point A or B was protrusive in the functional occlusal plane (FOP). We found that type B was more common for both Class I and Class II malocclusion. Further, in both Classes, type B cases exhibited an underlying Class III character. We also noted that both B groups had different structural craniofacial patterns relative to those seen in A groups. Both dental Class IA and Class IB had a skeletal Class II tendency. The difference between Class IA and Class IIA, or between Class IB and Class IIB was slight but quantitative. Class III and Class IIA individuals had distinctly different and essentially opposite underlying patterns. Most compensatory effects were ineffective in both Class IIA and Class III groups. However, the composite compensatory result in Class IB case was, for the most part, effective.