Objectives: This study aimed to analyze the impact of sleep bruxism (SB) on electromyography (EMG) activity and the thickness of the masseter and temporal and maximal molar bite force.
Method: Ninety individuals, aged between 18 and 45 years, were selected and divided into two groups: Group I (case group, 45 individuals with SB) and Group II (control group, 45 individuals without SB). A diagnosis of SB was made from polysomnography.
Results: The data obtained from EMG and the muscle thickness and the maximal molar bite force were tabulated (SPSS 21.0), normalized, and subjected to statistical analysis (p ≤ 0.05). Comparisons between the groups showed significant differences regarding the habitual chewing of hard food for the left temporalis muscle (p = 0.04) and the chewing of soft food for the right masseter muscle (p = 0.04), but no significant differences for the measurements of muscle thickness and maximal molar bite force.
Discussion: The present data suggest that SB negatively altered the masticatory muscles' functions. Based on the results of this research, it can be concluded that individuals with SB showed decreased EMG activity in the masticatory muscles.
Keywords: Bite force; Electromyography; Masticatory muscles; Sleep bruxism; Ultrasonography.