Double-masked research on effect and mechanism of polarized infrared light therapy to temporomandibular disorders (TMD)

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I.Short-term effects of the polarized light irradiation to TMD30 patients (27 female and 3 males, aged from 11 to 76) were selected. Their chief complaints were TMJ pain or angle of mandible pain on opening and/or chewing, and so on. According to the criteria proposed by Japanese Society for Temporomandibular Joint, patients were classified into five groups. Light irradiation was applied to the most painful area for 10 minutes with 2 seconds on-2 seconds off cycle during each visit.The level pain intensity was measured using Visual Analogue Scale(VAS). Interincisal distance of maximum opening was measured by ruler. Subjective estimates of Jaw Dysfunction and Activity Limitation were scored. The measurements of pre-irradiation, 2nd and 3rd visit were compared.Results were as follows.1)VAS score dropped significantly (P<0,01 : Wilcoxon signed rank test).2)More than 50% reduction of the VAS score was observed among half of patients.3)Average interincisal distance of maximum opening smoothly increased. Pain-free opening revealed the largest increment, and more than 10mm increment was observed among 25% of patients.4)Scores of the Jaw Dysfunction and Activity Limitation were decreased significantly (P<O.0I : Wilcoxon signed rank test).5)The best results were obtained among young Type I and II patients with short history of the present illness.II.Efficacy and mechanism of the light irradiation therapy under double-masked studyThe study was made to assess the efficacy of the polarized light irradiation to TMD by double-masked principle. The clinical responses described part I by sham irradiation was compared. Also, the skin blood flow by laser Doppler flowmetry and the skin temperature were measured. Consequently no definite conclusion can be drawn about the efficacy and mechanism of the polarized light irradiation. Further randomized clinical trials are needed in order to enable the benefits of light therapy to be more precisely and validly evaluated.