Objective This pilot study was planned to analyze masticatory activation in bruxism patients with and without attrition by ultrasonographic evaluation of mandibular adductor muscles. Methods Sixty bruxism patients (group 1: 30 without attrition, group 2: 30 with attrition) and an age-sex matched control of 30 (group 3) were clinically examined. The thickness of bilateral temporalis and masseter muscles during clench and rest was measured by ultrasonography. Results The mean muscle thicknesses were higher in bruxing patients than in controls. In group 2, the clench/rest ratio (C/R) of the right and left masseter and temporal muscles were higher than the control group (p = 0.03,p = 0.01,p = 0.04,p = 0.03, respectively). Conclusion The thickness of chewing muscles increases with bruxism. The occlusal forces in the teeth increase, and therefore, the tooth wear increases. Ultrasonographic muscle thickness can be used to determine muscle activity in bruxism patients.