Rheumatoid Arthritis-affected Temporomandibular Joint Pain Analgesia by Linear Polarized Near Infrared Irradiation

Purpose: To describe a new short-term treatment for pain in rheumatoid arthritis (RA)-affected temporomandibular joint (TMJ).

Clinical Features: We investigated four female patients (age 42.8+/-26.0 yr) with chronic rheumatoid arthritis affecting a single TMJ. Patients had received antirheumatic drugs such as sodium aurothiomalate, and as a result showed no symptoms in other body joints. Linear polarized near infrared radiation using Super Lizer was applied weekly with and/or without jaw movement to the unilateral skin areas overlying the mandibular fossa, anterior articular tubercle, masseter muscle and posterior margin of the ramus of the mandible. The duration of irradiation to each point was two seconds on and ten seconds off per cycle and the intensity at each point was approximately 138 J x cm(-2) at a wavelength of 830 nm. Interincisal distance was measured with maximal mouth opening in the absence and presence of pain before and after each treatment. Additionally, subjective TMJ pain scores assessed using a visual analog scale were performed for painful maximal mouth opening before and after each irradiation. TMJ pain disappeared after only four treatments. Moreover, painless maximal mouth opening without pain after irradiation in three patients was on average improved to 5.3+/-2.1 mm. However, one case was observed where the opening length prior to irradiation did not improve, despite the fact that the RA-affected TMJ pain had disappeared.

Conclusion: Application of linear polarized near infrared irradiation to patients with RA-affected TMJ pain is an effective and non-invasive short-term treatment.