Mandibular displacement: An evaluation of untreated and treated angle class II, division 1 malocclusions.

摘要

This retrospective cephalometric study investigated the effects of orthodontic treatment on rotation, and displacement of the mandible between untreated and treated Angle Class II, division 1 malocclusions. The untreated group consisted of fifteen males and thirteen females while the treated group consisted of fifteen males and fifteen females. Patients were growing at the time of treatment. Patients were treated nonsurgically, without the extraction of teeth or the use of functional appliances. Cephalometric data were obtained from three lateral cephalograms representing pretreatment (T1), posttreatment (T2), and at least two years post retention (T3). Thirty-seven variables were measured in each subject representing craniofacial morphology, tooth measurements, and mandibular displacement. Some variables required cranial base, maxillary, or mandibular superimposition. Statistical analyses included descriptive statistics, paired t tests, independent sample t tests and Pearson correlation coefficients. Significance was established at three levels of confidence: p < 0.05, p < 0.01, and p < 0.001. After treatment, the treated group exhibited a more vertical mandibular growth direction and a vertical displacement of pogonion. While no significant change in mandibular rotation or vertical movement of maxillary molars was observed in the treated group, a significant increase in the vertical movement of mandibular molars did occur during treatment. Vertical movement of maxillary and mandibular molars was not correlated to mandibular rotation and horizontal displacement of pogonion. Orthodontic treatment affected mandibular displacement in Angle Class II malocclusions. However, these treatment effects did not persist at the end of this study.