Three-dimensional assessment of condylar position and joint spaces after maxillary first premolar extraction in skeletal Class II malocclusion.

Abstract

This study sought to investigate the three-dimensional (3D) changes in anteroposterior, vertical and mediolateral positions and orientations of the mandibular condyle as well as joint space parameters following maxillary first premolar extraction and incisor retraction in skeletal Class II patients. Thirty patients were treated by orthodontic maxillary first premolar extraction at the Faculty of Oral and Dental Medicine, Cairo University, Egypt. Cone beam computed tomography (CBCT) analysis was performed in patients pre- and post-treatment. Sixty joints were evaluated based on the volumetric images, and the following 3D measurements were evaluated: (i) mandibular condylar position relative to the cranial base and the joint itself, (ii) condylar inclination and (iii) anterior, posterior, superior and medial joint spaces. There was a statistically significant (P≤.05) posterior positioning of the condyle relative to the vertical plane. The distance increased significantly from 5.77 to 6.82mm as this plane is anterior to the mandibular condyle. There was an increased anterior joint space (from 3.10 to 3.90mm) and decreased posterior joint space (from 2.78 to 2.23mm) following treatment. No changes were observed in mediolateral and vertical condylar positions. Posterior positioning of the condyle after orthodontic extraction and incisor retraction may occur, but its clinical significance requires further assessment in future studies.