Changes in Morphology and Bone Mineral Density of Human Mandibular Condyle During Orthodontic Treatment

The objective of the present study was to investigate whether orthodontic treatment alters the morphology and bone mineral density (BMD) distribution of the mandibular condyle in growing adolescent patients. Cone-beam computed tomography (CBCT) images were retrospectively analyzed for 29 patients (10 males and 19 females, aged 12.5 to 17.0 years) treated with full fixed orthodontic appliances. The right and left mandibular condyles were digitally isolated. For the internal control sample, the basal cortical bone (CB) at both mandibular first molar sites was also digitally dissected. A frequency plot of the CBCT gray values, proportional to BMD, was analyzed to calculate the mean and the 5th percentile of low and high gray values (Low5 and High5). Morphological changes in the condylar surface were assessed based on temporomandibular joint osteoarthritis (TMJOA) counts. Lateral cephalometric radiographs were used to measure facial morphology parameters and classify skeletal patterns. The cervical vertebral gray values of the same patients were compared. No radiographic signs of TMJ disorder were observed with no significant difference in TMJOA counts between before and after treatment (p = 0.56). The volume, mean and Low5 gray values of the mandibular condyle, facial morphology parameters, and cervical vertebral gray values significantly increased following orthodontic treatment (p < 0.05). Skeletal Class II patients exhibited greater changes in mean, Low5, and High5 mandibular condyle gray values compared to their Class I patients (p < 0.05), whereas cervical vertebral gray values were not significantly influenced by skeletal classification (p > 0.19). The findings suggest that orthodontic treatment, combined with natural patient growth, contributes to nonpathological condylar alterations in adolescent patients.