Although a recent study suggested the involvement of RANKL and osteoprotegerin (OPG) in the pathogenesis of bone-destructive disease, no study has focused on the RANKL:OPG ratio in the synovial fluid of patients with temporomandibular joint (TMJ) disorder. This communication reports on the concentrations of RANKL and OPG in synovial fluid from TMJ patients and healthy control individuals. In contrast to an unchanged concentration of RANKL, a strong decrease in the concentration of OPG was detected in the synovial fluid from patients with TMJ internal derangement. Treatment with the synovial fluid of osteoarthritis (OA) patients resulted in the high production of osteoclast-like cells from blood mononuclear cells in vitro, as well as in pit formation in dentin slices. The addition of anti-RANKL IgG or OPG attenuated OA-synovial fluid-induced osteoclast formation, suggesting that the increase in the RANKL:OPG ratio in the microenvironment of the joint has the potential to induce osteoclastogenesis in TMJ osteoarthritis.

Arthrocentesis is the surgical treatment of choice for temporomandibular joint (TMJ) disorders.Many studies of arthrocentesis have reported an excellent clinical outcome. No previous report, however, has described the use of multiple arthrocenteses to treat TMJ dysfunction. We evaluated the efficacy of two consecutive arthrocenteses followed by mouth opening exercises during treatment with non-steroidal anti-inflammatory drugs (NSAID) as a primary treatment for TMJ osteoarthritis.The subjects of this study were selected from a consecutive series of patients with unilateral moderate-to-severe TMJ dysfunction newly diagnosed at the TMD Clinic, Aichi-Gakuin University Hospital during a 1-year period.Thirty-six patients with osteoarthritis as documented by magnetic resonance imaging underwent two consecutive arthrocenteses at a 2-week interval followed by mouth opening exercises and NSAID administration. The patients were postoperatively examined every 2 weeks for 12 weeks. Clinical evaluations included pain-related measures on visual analog scales (VAS, 0-100) and range of motion. At the completion of treatment, patients had sustained pain relief and improved mouth opening. Factors that affected clinical outcome of TMJ function were assessed.Of the 36 patients who underwent two consecutive arthrocenteses, 28 showed substantially improvement on follow-up at 12 weeks. The range of motion (median) increased from 28 mm to 39.5 mm. VAS pain-scores on mouth opening and chewing significantly decreased from 54 and 53 to 10 and 7, respectively. The interference score for activities of daily life also decreased from 33.5 to 9. A longer duration of TMJ symptoms before the procedure was found to affect the outcome.

Arthrocentesis is the surgical treatment of choice for TMJ disorders. Many studies of arthrocentesis have been performed, with excellent clinical outcomes. No previous study has used multiple arthrocenteses to

We report a case of mouth-closing disturbance caused by yawning. A 29-year-old man suddenly noticed mouth-closing disturbance and pain in the left temporomandibular joint after yawning. Magnetic resonance imaging (MRI) showed that the relation between the condyle and the disk was normal, but these structures were anteriorly displaced when the mouth was closed. An unsuccessful attempt was made to reduce the displaced condyle by manipulation. Then, the mandible was retracted elastically. The patient noticed that his occlusion was reduced the following morning. MRI showed anterior disk displacement without reduction, with enlargement of the posterior part of the disk. Therefore, we concluded that the mouthclosing disturbance was caused when the anteriorly displaced disk was reduced on yawning, and backward movement of the condyle was restricted by the deformed posterior part of the disk on closing the mouth.