Longitudinal cephalometric growth of untreated subjects with Class II Division 2 malocclusion

Introduction: Our objective was to evaluate the craniofacial growth of subjects with untreated Class II Division 2 malocclusion. Methods: A mixed longitudinal sample of 39 white Class II Division 2 subjects was analyzed at 5 time points: T1 (6 or 7 years), T2 (9 or 10 years), T3 (12 or 13 years), T4 (15 or 16 years), and T5 (18 or 19 years). They were compared with an age-and sex-matched sample of Class I controls. Seventeen measurements (12 angular, 5 proportional) were computed. Multilevel modeling procedures were used to statistically describe the growth changes and to evaluate group differences. Results: There were no group differences in the relative sizes and anteroposterior positions of the jaws during childhood, adolescence, or early adulthood. Subjects with Class II Division 2 malocclusion demonstrated significantly (P < 0.05) smaller mandibular plane angles, smaller palatal-to-mandibular plane angles, larger posterior-to-anterior facial height ratios, smaller gonial angles, smaller cranial base angles, larger interincisal angles, and more retroclined maxillary incisors than did the Class I subjects. The hypodivergent patterns were established early and became more pronounced over time. Group differences in the mandibular plane angle, palatal-to-mandibular plane angle, gonial angle, interincisal angle, and maxillary incisor-to-cranial base angle, as well as the posterior-to-anterior facial height ratio all increased over time; the difference in the cranial base angle remained unchanged over time. Retroclination of the maxillary incisors occurred primarily during the early mixed dentition. Conclusions: Subjects with Class II Division 2 malocclusion are more hypodivergent and have more upright maxillary incisors than do subjects with Class I occlusion. Hypodivergence establishes itself early and increases progressively through early adulthood; maxillary incisor retroclination occurs early.