Research about the effects of occlusal interferences on masseter and anterior temporalis muscles with electromyographic method

Tolunay SG. Research about the effects of occlusal interferences on masseter and anterior temporalis muscles with electromyographic method. Yeditepe University Health Sciences Institute, Department of Prosthodontics, PhD Thesis, Istanbul, 2013. The purpose of our study is comparing masseter and temporalis anterior muscles? EMG activity during max voluntary clenching by changing the existing occlusal support. The study was performed on 30 different subjects, who are suitable for all research criteria, in February 2013. Intraoral and extraoral tests are completed, natural contacts are detected and recorded with the T-Scan® III 5.2 computerized device. Then, bilateral masseter and anterior temporalis muscle EMG activity during max voluntary clenching in physiological resting position and maximum intercuspidation is recorded. Occlusal interferences are sequentially created with the standardized 1 mm composite material on the right first Premolar buccal cusp (E1), right first Molar distobukkal cusp (E2) and both right-left first Molar distobukkal cusps (E3). The average of EMG recordings during maximum intercuspal position is deployed as a standard for subsequent data analysis. It is observed that the statistical average of max voluntary clenching is significantly reduced after the insertion of E1, E2, and E3 interferences. The largest decrease among all muscles is on the left anterior temporalis muscle at E1 interference. After the insertion of E1 and E2 interferences, decrement in average EMG during max voluntary clenching is higher on balancing side muscles than the working side muscles. During max voluntary clenching, on all muscles, except for the left masseter muscle; the decrease of EMG level at E1 is statistically significantly higher than E2. On all muscles, the decrease of EMG level at E1 is statistically significantly higher E3. As a result, in the presence of occlusal interference, masticatory muscles are forced to contribute to the stabilization and change the amount of contraction with a compensation mechanism. Depending on natural premature contact, subjects might respond differently to interferences.