The relationship between mandibular rotation and osseous structure of the TMJ in pre-surgery orthognathic patients : A cone beam CT study

Abstract

The aim of the study was to assess the relationship between vertical skeletal pattern in terms of mandibular rotation and osseous structural changes of the TMJ in pre- surgical orthognatic patients. TMJ skeletal morphology was evaluated in cone beam computer tomography images of 117 consecutive patients with Class II and Class III dentofacial deformities according to the research diagnostic criteria of the osseous components of the TMJ related to the maxillary-mandibular plane (MM) angle. The distribution of the number and percentage of joints with structural changes in Class II was markedly different in groups divided according to the MM angle. Statistically significant increase was found in the percentage of TMJ's with osseous changes separately for each side, i.e., right (p=0.001), left (p=0.04) and both together (p=0.0001), in the Class II patient group, an increased MM angle indicated backward rotation of the mandible. In Class III patients, there were no statistically significant differences in the number of joints with TMJ structural changes. The presence of mentioned changes was asymmetrical between the left and right joints in both the Class II and Class III patient groups. In conclusion, structural changes in the osseous parts of the TMJ are more common in patients with Class II skeletal dentofacial deformities with backward rotation of the mandible than in Class III pre-surgery orthognathic patients.