Relationship between dentofacial morphology and mandibular movement from rest position to maximum intercuspation in Class II division 1 malocclusion patients

BACKGROUND: The objective of this study was to determine the relationship between dentofacial morphology and mandibular movement from rest position to maximum intercuspation in Class II division 1 malocclusion patients.MATERIALS AND METHODS: The sample comprised of 45 patients who were 10–14 years old and had Class II division 1 malocclusions. Eighteen cephalometric variables were evaluated to determine the dentofacial morphology using lateral cephalograms. Mandibular movements were recorded from mandibular rest position to maximum intercuspation using mandibular kinesiography. Spearman's correlation coefficient was used to analyze the relationships between mandibular movement and other dentofacial variables.RESULTS: Mandibular movement in the anteroposterior dimension was significantly negatively correlated with the curve of Spee (COS) (r = −0.45) and freeway space (r = −0.44) and positively correlated with the sella-nasion-mandibular plane (SN-MP) angle (r = 0.47) and the Frankfort-mandibular plane angle (FMA) angle (r = 0.44). Two types of mandibular movement in the anteroposterior dimension were observed. Twenty-six of 45 patients (57.8%) exhibited posterior mandibular movement from rest position to maximum intercuspation (backward group) and 19 subjects (42.2%) presented anterior movement (forward group). COS and freeway space were greater in the backward group. The SN-MP and FMA angles were higher in the forward group.CONCLUSIONS: COS, freeway space, and mandibular plane angle may relate to mandibular movement from rest position to maximum intercuspation in Class II division 1 malocclusion. Patients with deep COS combined with a large freeway space and smaller mandibular plane angle tend to present posterior mandibular movement from rest position to maximum intercuspation.