Progression of TMJ Lesions Is Not Related to Orthodontic Treatment

Objectives: Using cone beam computed tomography (CBCT) and the RDC/TMD image analysis criteria we assessed the changes in the temporomandibular joints (TMJs) of individuals who underwent orthodontic treatment.
Methods: The sample comprised of pre- and posttreatment CBCTs of 76 individuals who completed comprehensive orthodontic treatment (n = 152 joints; mean age: 14.7 years). CBCTs were taken according to a standard protocol (120kVp, 37.10mA, FOV: 23cm x 17cm, resolution: 0.3mm voxels, acquisition time: 17.8s). Participants were classified into three groups and matched for age and gender: 1) Control [normal TMJ]; 2) Remodeling [TMJ with localized sclerosis and/or flattening]; 3) Case [TMJ with degenerative joint disease (DJD)]. Five radiographic findings, based on RDC/TMD image analysis criteria, were assessed: a) articular surface flattening; b) subcortical sclerosis; c) osteophyte; d) surface erosion; and e) subcortical cyst. A calibrated clinician blinded to the group allocation and time point of CBCTs obtained the definitive radiographic diagnoses. Radiographic changes in the TMJs after orthodontic treatment were analyzed using marginal and conditional regression models.
Results: After orthodontic treatment, TMJs with normal diagnoses decreased from 54 to 43 (20%), TMJs with remodeling increased from 62 to 76 (22.6%), and TMJs with DJD decreased from 36 to 33 (8%). At post-treatment, 52.6% of TMJs had the same diagnosis, 25% had a worse diagnosis, and 22.4% had a better diagnosis. The likelihood of having a worse diagnosis post-treatment was statistically significant only when there was a pre-treatment diagnosis of DJD (OR: 42.25; p <0.001) or remodeling (OR: 6.02; p = 0.001).
Conclusions: Radiographic changes in the TMJ after orthodontic treatment varies. In our study, 75% of the pretreatment TMJ diagnoses were either the same or better following orthodontic treatment.