Hard tissue structural changes in TMJ morphology prior to orthodontic therapy: A complex motion tomographic study

Objective: Temporomandibular joint (TMJ) disorders have been investigated for years due to their probable association with the neuromasticatory apparatus and the myoskeletal framework of the head and neck. In this study, we explored hard tissue structural changes within the TMJ (condyle, glenoid fossa, articular eminence, and joint space) using complex motion tomography. A correlation between these morphologic changes and clinical symptoms of disc-related TMJ disorders was attempted. Method and Materials: Submentovertex and complex motion tomograms were taken on 114 TMJs from 57 patients who were referred for preorthodontic TMJ imaging. The TMJs were categorized into joints that were symtomatic (S) and asymptomatic (AS). The tomograms were evaluated independently by a board-certified oral and maxillofacial radiologist, and the data were recorded. Results: In the majority of the patients with or without joint symptoms, the glenoid fossa, anterior slope, and posterior slope of the articular eminence were morphologically normal in appearance. The condylar position of the joints without symptoms was more posterior compared to those with symptoms within the glenoid fossa. Condylar heads were abnormal in the majority of the patients, both in coronal view and sagittal view, regardless of their symptomatology. Both groups of joints exhibited abnormal joint space and range of motion. The Fisher exact test was used to determine the significance of the difference between the morphology of symptomatic and asymptomatic joints. Of the results obtained, only the condylar head in coronal view (P = .0001) and joint space (P = .0007) demonstrated any statistical significance in terms of deviation from the norm between the two groups. Conclusion: Examination of hard tissue structures alone is insufficient to support the joint association in the presence of TMJ-related clinical symptoms. Simultaneous MR imaging may significantly increase the predictability of any clinical correlation. Keywords: complex motion tomography, condylar morphology, coronal images, sagittal images, temporomandibular joint