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Effects of phototherapy on muscle activity and pain in individuals with temporomandibular disorder: a study protocol for a randomized controlled trial.


Background: According to the International Association for the Study of Pain(IASP), the term temporomandibular disorder (TMD) regards a subgroup oforofacial pain, the symptoms of which include pain or discomfort in thetemporomandibular joint, ears, masicatory muscles and neck on one or bothsides as well as joint sounds, limited mandibular movements or mandibulardeviation and difficulties chewing. Phototherapy, such as low level laser therapy(LLLT) and light-emitting diode (LED) therapy, is one of the resources used totreatment muscle pain. Thus, there is a need to investigate therapeuticresources that combine different wavelengths as well as different light sources(LLLT and LED) in the same apparatus. Question: The aim of the proposedstudy is to evaluate the effects of four different doses of phototherapy on pain,activity of the masticatory muscles (massester and anterior temporal bilaterally)and joint mobility in individuals with temporomandibular disorder (TMD). Afurther aim is to determine the cumulative effect 24 and 48 hours after a singlesession. Methods/Design: A placebo-controlled, double-blind, randomized,clinical trial will be carried out involving 72 women between 18 and 40 years ofage with a diagnosis of myogenous TMD. The participants will then be randomlyallocated to four groups totaling 18 individuals per group. Three groups will besubmitted to a single session of phototherapy with different light sources andone group will receive placebo therapy: Group A (2.62 Joules); Group B (5.24Joules); Group C (786 Joules); and Group D (0 Joules). The followingassessment tools will be administered on four separate occasions (baseline andimmediately after, 24 h after and 48 h after phototherapy). Pain intensity will beassessed using the visual analog scale for pain, while pain thresholds will bedetermined using algometer, and electromyographic EMG analysis on themasseter and anterior temporal muscles. Discussion: The study will supportthe practice of evidence-based to the use of phototherapy in individuals with amyogenous TMD. Data will be published after the study is completed. (AU)