Mandibular skeletal and dental asymmetry in Class II subdivision malocclusions

Mandibular symmetry was compared between a group of 28 subjects exhibiting Class II subdivision malocclusions and 30 subjects with Class I malocclusions who served as the control group. With submentovertex radiographs, symmetry was assessed by measuring the relative difference in spatial position of mandibular landmarks in both anteroposterior and transverse dimensions as determined by coordinate systems representing the cranial floor, mandible, and mandibular dentition. Only those variables representing the anteroposterior difference between right and left mandibular molar positions showed a statistically significant difference between the groups. Whether the position of the mandibular molars was measured relative to the cranial floor or within the mandible itself, the mandibular first molar was located more posteriorly on the Class II side of the subdivision malocclusion within a mandible that exhibited no other unusual asymmetry.