Osteoarthritis is characterized by osseous changes and frequently seen in temporomandibular joints (TMJs) with long-standing disk displacement and no reduction. Disk displacement seems to be a precursor of osteoarthritis. Several studies have shown that jaw deformity lead to an osseous change of the mandibular condyle. We have postulated that each of jaw deformities, such as skeletal class II or class III is related to characteristic osseous changes of the mandibular joint, regardless of disk status. The purpose of this study is to examine a difference in osseous abnormality of the mandibular condyle between skeletal class II and class III.
Methods:
Twenty-four patients had evidence of skeletal class II and 13 patients were diagnosed as skeletal class III. Prior to the examination in osseous abnormalities, disk derangement was assessed in magnetic resonance (MR) images of 52 TMJs in 37 patients from both skeletal class II and class III. It was proven that there is no difference in status of disk between both groups. Following this result, osseous abnormalities of the mandibular condyle were classified as erosion, osteophytosis, or deformity in MR images. Statistical analysis was performed with the Fisher's exact test and where a probability of less than 0.05 was considered statistically significant.
Results:
In patients with skeletal class II, 25 joints (69.4%) showed erosion, 9 were osteophytosis (25.0%), and the remaining 2 joints (5.6%) demonstrated deformity, whereas with skeletal class III, 11 joints (68.8%) were osteophytosis and 5 joints (31.2%) demonstrated deformity. There is no statistical difference in distribution of osseous changes for these jaw deformities.
Conclusion:
Each of jaw deformities appears to be related to various types of osseous abnormalities in the mandibular condyle, respectively.