Are Panoramic Radiographs Predictive of Temporomandibular Joint Synovitis in Children With Juvenile Idiopathic Arthritis?
The gold standard for diagnosis of temporomandibular joint (TMJ) synovitis in children with juvenile idiopathic arthritis (JIA) is magnetic resonance imaging (MRI) with gadolinium contrast.1 MRIs are costly, time consuming and may require sedation or general anesthesia.2 Since panoramic radiographs are often obtained during routine dental/oral surgical care, it would be useful to know if there are specific findings on these films indicative of TMJ synovitis. The purpose of this study was to answer the following question: Among children with JIA, are there particular panoramic x-ray findings associated with TMJ synovitis?
Materials and Methods
The sample included children with JIA who were evaluated by the Oral and Maxillofacial Surgery service at Boston Children’s Hospital. All subjects had an MRI with contrast and a panoramic radiograph within a six month interval. Data included (1) demographics, gender, age; (2) MRI findings, presence or absence of TMJ synovitis and (3) panoramic findings, accentuated antegonial notch, abnormal condyle morphology, erosion, decreased vertical or anterior-posterior dimensions, short ramus/condyle unit (RCU) length. Patients/joints were classified as positive or negative for TMJ synovitis on MRI. Bivariate statistics were used to identify associations between TMJ synovitis on MRI and panoramic x-ray findings. Multiple logistic regression analyses were used to compute adjusted odds ratios. For all analyses, p-value <.05 was considered significant.
Results
There were 61 patients evaluated during the study period and 30 patients (21 females) with a mean age of 11.1 years (range 5-16 years) met inclusion criteria. Of these, 15 subjects had MRI scans positive for synovitis: bilateral, 9 patients (18 joints) and unilateral, 6 patients (6 joints). The remaining 15 subjects did not have MRI evidence of synovitis.
In the synovitis group, there were 13 subjects who had abnormal panoramic findings: abnormal condyle morphology (13 patients, 18 joints), accentuated antegonial notch (7 patients, 9 joints), and short RCU length (5 patients, 5 joints). In the non synovitis group, abnormal panoramic findings included: abnormal condyle morphology (9 patients, 12 joints), accentuated antegonial notch (5 patients, 6 joints) and short RCU length (4 patients, 4 joints).
Abnormal condyle morphology and accentuated antegonial notching on panoramic x-ray were found to be significantly correlated with synovitis (p=.0005 and .044, respectively). Short RCU length was not a significant predictor of synovitis (p=.168). Abnormal condyle morphology was found to have high sensitivity and specificity (75%, 71.4%, respectively). Accentuated antegonial notching had low sensitivity but high specificity (37.5%, 81%, respectively).
In a multiple regression model, abnormal condyle morphology was significantly associated with an increase in likelihood of TMJ synovitis (OR 5.5, 95% CI: 1.59-19.2, p=.007). Joints exhibiting both abnormal condyle morphology and accentuated antegonial notching were 7.5 times as likely to have synovitis (OR 7.55, 95% CI: 1.66-34.4, p=.009).
Conclusions
Results of this preliminary study indicate in this sample of children with JIA, abnormal condyle morphology and accentuated antegonial notching on a panoramic radiograph correlate with TMJ synovitis on MRI.
References
- Abramowicz S, Cheon J, Kim S, Bacic J, Lee EY. Magnetic resonance imaging of temporomandibular joints in children with arthritis. J Oral and Maxillofac Surg. 69:2321-2328, 2011.
- Stoll ML, Sharpe T, Beukelman T, Good J, Young D, Cron RQ. Risk factors for temporomandibular joint arthritis in children with juvenile idiopathic arthritis. J Rheumatol. 39:1880-1887, 2012.