Clinical Utility of bone Scan in the Diagnosis of Temporomandibular disorders

Bone scan is a very sensitive diagnostic imaging test for detecting bone and joint disorders. So it might be useful in the diagnosis of temporomandibular disorders of the joint origin. Thus, the effectiveness of bone scan for detecting temporomandibular joint(TMJ) diseases and differentiating the TMJ disc displacement from the TMJ arthritis was evaluated. Bone scan was done in 21 patients with TMJ disc displacement (I3 unilaterally affected, 8 bilaterally affected), 26 patients with TMJ arthritis (23 unilateral, 3 bilateral), and 39 volunteers with no signs, symptoms, or history of TMJ disease TMJ simple uptake rate(SUR) and difference of both TMJ SUR were calculated from the 100,000 count lateral image of head and neck region in 99mTc MDP bone scan. Transcranial and panorama X-ray examination was also done in all patients. TMJ SUR(%) were 1.67 ±0.606 in TMJs affected with arthritis, 1.350±0.351 in TMJs affected with disc displacement, and 1.084±0.172 in TMJs of controls Significant differences were demonstrated among them(p<001). Difference of both TMJ SUR was highest in patients with unilateral TMJ arthritis(0.608±0.533, p<001), and there is no significant difference between that of controls and that of unilateral TMJ disc displacement patients(0.062±0.063 vs 0.122±0.100). TMJ SUR of joint with bone change on X-ray finding was not significantly different from that of joint with normal X-ray finding. Those in patients with unilateral TMJ disc displacement(69.6% and 87% vs 23.1% and 23%). The proportions of patients with increased TMJ SUR and difference of both TMJ SUR(>mean+2SD of controls) in unilateral TMJ arthritis patients were significantly higher than those in patients with unilateral TMJ disc displacement(69.6% and 87% vs 23.1% and 23%). Conclusively, bone scan may help to detect TMJ disease and differentiate TMJ disc displacement from TMJ arthritis.