A 3D mirroring and colormap asymmetry study of Class II subdivision patients

INTRODUCTION Patients with Class II subdivision malocclusion present skeletal and dental asymmetries. The purpose of this study is to assess those asymmetries by 3D mirroring and colormap quantification. METHODS This study analyzed 50 initial CBCTs divided in two groups: Class I (control group) and Class II subdivision (study group) malocclusion patients. CBCTs were oriented and full skull was segmented generating a 3D model. The right side of the 3D models was mirrored, using a midsagittal plane as reference, resulting in a perfectly symmetric skull based on two right sides. Original and mirrored models were superimposed on the unchanged right half, and differences were quantified using a colormap. Eight regions of interest were assessed: gonion, mandibular front, maxillary front, zygomatic process, maxillary and mandibular canine and molar areas. RESULTS Statistically significant differences using the Mann Whitney test were found in six of the eight evaluated areas when comparing the control to the study group. The maxillary areas did not show any difference between the groups. CONCLUSIONS Patients with Class II subdivision malocclusion show true skeletal and dental asymmetries when comparing right and left sides. The maxilla showed no significant skeletal asymmetry, but the maxillary teeth were positioned more mesially on the Class II side. The maxillary canine on the Class II side was also more bucally positioned. The mandible showed significant asymmetries with both skeletal and dental areas in the Class II side more distally and bucally positioned.