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

Abstract

BackgroundAccording to the International Association for the Study of Pain (IASP), the term temporomandibular disorder (TMD) regards a subgroup of orofacial pain, the symptoms of which include pain or discomfort in the temporomandibular joint, ears, masticatory muscles and neck on one or both sides, as well as joint sounds, limited mandibular movements or mandibular deviation and difficulties chewing. Phototherapy, such as low-level laser therapy (LLLT) and light-emitting diode (LED) therapy, is one of the resources used to treatment muscle pain. Thus, there is a need to investigate therapeutic resources that combine different wavelengths as well as different light sources (LLLT and LED) in the same apparatus.The aim of the proposed study is to evaluate the effects of four different doses of phototherapy on pain, activity of the masticatory muscles (masseter and bilateral anterior temporal) and joint mobility in individuals with temporomandibular disorder. A further aim is to determine the cumulative effect 24 and 48 hours after a single session.Methods/DesignA placebo-controlled, double-blind, randomized, clinical trial will be carried out involving 72 women between 18 and 40 years of age with a diagnosis of myogenous TMD. The participants will then be randomly allocated to four groups totaling 18 individuals per group. Three groups will be submitted to a single session of phototherapy with different light sources, and one group will receive placebo therapy: Group A (2.62 Joules); Group B (5.24 Joules); Group C (7.86 Joules); and Group D (0 Joules). The following assessment tools will be administered on four separate occasions (baseline and immediately after, 24 h after and 48 h after phototherapy). Pain intensity will be assessed using the visual analog scale for pain, while pain thresholds will be determined using algometer, and electromyographic (EMG) analysis on the masseter and anterior temporal muscles.DiscussionThe study will contribute to the practice of the evidence-based use of phototherapy in individuals with a myogenous TMD. Data will be published after the study is completed.Trial registrationThis study is registered with the Brazilian Registry of Clinical Trials, NCT02018770, date of registration: 7 December 2013.

Cervical spine range of motion, posture and electromyographic activity of masticatory muscles in temporomandibular disorders

“…Prior to sEMG signal collection, the skin was cleaned with a soft sponge and cotton wool soaked in 70% alcohol [24]. The electrodes were placed on the muscle belly of each muscle, according to the direction of the muscle fibers and palpation of the muscle mass during contraction [25].…”

Is there a difference in the electromyographic activity of the masticatory muscles between individuals with temporomandibular disorder and healthy controls? A systematic review with meta‐analysis

“…Based on the assumption that certain pathologic or dysfunctional conditions can be identified by abnormal activity of the masticatory muscles, the evaluation of muscle activity using electromyography has been used to evaluate changes in the masticatory system due to TMD under different conditions, such as at rest, during chewing (isotonic contraction), and during maximum intercuspation (isometric contraction) as well the clinical effects of different therapeutic approaches used to treat this disorder …”

Effects of exercise training and photobiomodulation therapy (EXTRAPHOTO) on pain in women with fibromyalgia and temporomandibular disorder: study protocol for a randomized controlled trial

“…Moreover, LLLT is reported to reduce bradykinin, histamine release, swelling, pain-associated molecules, and inflammation phase and to induce muscle relaxation [18, 19]. Similar results have been shown with LED therapy, which has a minor cost and better equipment durability [20]. …”