The hyperboloid device does not affect masticatory electromyographic activity during jaw movements in individuals with temporomandibular joint disorders

Abstract Introduction The hyperboloid is a masticatory device made of silicone with an hourglass (hyperbolic) shape that has been used as an aid to jaw functional orthopedic therapy. Objective To evaluate whether the hyperboloid device affects electromyographic (EMG) activity of the masticatory muscles during jaw movements in individuals with temporomandibular joint disorders (TMD) compared to controls. Methods The study sample consisted of 49 participants divided into two groups: mild, moderate and severe TMD (TMD group; n = 25) and a control group (n = 24). We evaluated EMG activities of temporal and masseter muscles bilaterally during jaw protraction and retraction, and left and right lateralization with and without the use of the hyperboloid device. Statistical analyses were performed using two-way ANOVA with two factors: group (healthy and TMD) and situation (with or without the use of the hyperboloid). Results We found higher EMG activity in the left temporal in the TMD group and no difference in EMG activities with the use of the hyperboloid device. Conclusion The use of the hyperboloid device did not affect EMG activity of the muscles evaluated in the groups studied. We found higher EMG activity of the left temporal muscle in participants with TMD. Long-term randomized studies should be conducted in individuals with TMD to investigate the effects of functional orthopedic therapy using the hyperboloid device with visual and quantitative feedback.