Are panoramic radiographs predictive of temporomandibular joint synovitis in children with juvenile idiopathic arthritis?

PURPOSE: To identify specific panoramic radiographic findings associated with temporomandibular joint (TMJ) synovitis in children with juvenile idiopathic arthritis (JIA).

MATERIALS AND METHODS: This was a retrospective study of children with JIA evaluated at Boston Children's Hospital. Patients were included if they had a confirmed diagnosis of JIA, a panoramic radiograph, and a contemporaneous TMJ magnetic resonance imaging (MRI) study with contrast. Medical records and imaging studies were reviewed to document demographic, panoramic (accentuated antegonial notch, short ramus and condyle unit [RCU] length, and abnormal condyle morphology: decreased condyle anteroposterior or superoinferior dimension) and MRI findings. The outcome variable was the presence or absence of TMJ synovitis on MRI. Descriptive and bivariate statistics and logistic regression models were used to identify associations (significant at P ≤ .05).

RESULTS: Thirty patients (21 girls) with a mean age of 11.1 years (range, 5 to 16 yr) met the inclusion criteria. Of these, 15 patients had MRI scans positive for synovitis (bilateral in 18 joints in 9 patients and unilateral in 6 joints in 6 patients). The remaining 15 patients did not have evidence of synovitis on MRI. In the synovitis group, 18 of 24 joints (75%) showed abnormal panoramic findings (abnormal condyle morphology in 18 joints, accentuated antegonial notch in 9 joints, or short RCU length in 5 joints). In the nonsynovitis group, 15 of 36 joints (42%) showed abnormal panoramic findings (abnormal condyle morphology in 12 joints, accentuated antegonial notch in 6 joints, or short RCU length in 4 joints). Abnormal condyle morphology and accentuated antegonial notching on panoramic radiographs were found to be significantly correlated with synovitis (P = .0005 and .044, respectively). In a logistic regression model, abnormal condyle morphology was significantly associated with an increase in likelihood of TMJ synovitis versus those joints with normal condyle morphology (P = .007). Joints with abnormal condyle morphology and accentuated antegonial notching were 7.5 times as likely to have synovitis (P = .009) versus those joints without abnormal panoramic findings.

CONCLUSION: Results of this preliminary study indicate that in this sample of children with JIA, the combination of abnormal condyle morphology and accentuated antegonial notching on a panoramic radiograph correlates with TMJ synovitis on MRI.