Electromyographic Activity Changes of Jaw-Closing Muscles in Patients with Different Occlusion Schemes after Fixed Prosthetic Restoration

Abstract

Summary Background/Aim: To investigate the electromyographic (EMG) activity changes of jaw-closing muscles in patients with different occlusion schemes and posterior edentulous span, after the placement of teeth-supported fixed partial denture (FPD). Material and Methods: The study sample consisted of 20 patients (10 men and 10 women, the mean age being 50 years) with a posterior edentulous area that includes two missing premolars or one premolar and one molar. The participants were divided into two groups with different occlusion schemes: canine-guided occlusion (CGO) and group function occlusion (GFO). The metal-ceramic FPD were fabricated according to the clinic-standardized protocol. EMG activities of masseter and anterior temporalis patients’ muscles were recorded with bipolar surface electrodes during maximal voluntary clenching. EMG evaluation was repeated twice: (T1) before the fabrication of FPD (T2) after eight weeks of FPD cementation and intraoral functioning of restoration. The data were subjected to Analysis of Variance–ANOVA within the methodological framework of the General Linear Models with Repeated Measures. The Bonferroni test was used to compare multiple mean measures. Statistical analysis was conducted with SPSS ver. 11.5. The level of significance was predefined at a=0.05. Results: Group 1 with CGO presented significantly higher levels of masseter (mean maximum EMG average before 79.36μV and 139.68μV after) and temporalis (mean maximum EMG average before 79.07μV and 149.37μV after) EMG activity after FPD placement. Group 2 with GFO also showed significantly higher levels of masseter (mean maximum EMG average before 61.57μV and 165.30μV after) and temporalis (mean maximum EMG average before 56.94μV and 133.08μV after) EMG activity after the prosthetic restoration. Conclusions: It may be concluded that fixed prosthetic restoration, in both patients with canine-guided and group function occlusion, results in increased EMG jaw-muscle activity.