Electromyographic, ultrasonographic and clinical evaluation of short-term stabilization splint therapy

Objectives: Effects of occlusal splints on masticatory muscles should be evaluated in a more objective manner. The purpose of this study was to assess the short term success of the stabilization-type occlusal splint and its effect on the masseter muscle using electromyography and ultrasonography, and to compare the data obtained with clinical evaluations of the patients. Methods: Stabilization-type occlusal splints were fabricated for 13 patients with signs and symptoms of bruxism. The level of distress of the patients was determined with visual analogue scale (VAS). Clinical evaluations with respect to amount of mouth opening and muscle tenderness on palpation were also determined. Electromyographic and ultrasonographic data were recorded from the masseter muscle. A special method was developed for the standardization of the location and the direction of the probe used for obtaining ultrasonographic records. To describe pre- and post-treatment results, Wilcoxon test, t-test and ANOVA were used. Results: Changes between pre- and post-treatment electromyographic data were found to be statistically insignificant. However, significant changes were observed as regards VAS and clinical evaluations. The thickness of the masseter muscle, as determined by ultrasonography, changed significantly for both the relaxed (p=0.019) and the maximum clenching (p=0.043) positions at the right and left side as a result of application of splint. The asymmetry between the size of the right and left masseter muscles decreased significantly with the application of splint. Conclusion: Evaluating the short-term success of treating individuals with bruxism by application of splint, significant improvement was observed in terms of patient complaints, clinical findings and size changes of the masseter muscle. After splint therapy, the right-left asymmetry of the masseter muscles was decreased and equilibration was established. The efficacy of stabilization-type splint application can be assessed more objectively by using techniques such as ultrasonography along with clinical evaluation and patient data.