ABSTRACT
THE AIM OF THE STUDY: Was to assess the impact of masticatory muscles hypertonicity on the bite formation. MATERIALS AND METHODS: The study comprised 60 patients aged 7-14 years. Group 1 consisted of 20 individuals with Angle class 1 occlusion without masticatory muscle hypertonicity. Group 2 comprised 20 patients with class II malocclusion with hypertonicity of the masticatory muscles, group 3 - 20 patients class II malocclusion and no hypertonic masticatory muscles. All patients were examined according to common diagnostic protocol that included electromyography of the temporal and masticatory muscles at rest and in dynamics). RESULTS: In group 1 the mean IMPACT at rest was 242.8±133.6 µV, IMPACT during contraction was 880.50±201.5 µV; in group 2 - 797.9±413.0 and 1561.23±568.0 µV; in group 3 - 236.7±93.5 and 955.60±295.5 µV, correspondingly. The ratio of the activity of the temporal muscles to the masticatory muscles with neutral occlusion at rest correlates as 1:09, with compression 1:1. In patients with distal occlusion and the presence of hypertonicity at rest, the temporal muscles correspond to the chewing proper as 1:0.8, and with compression 1:09. CONCLUSION: The estimated ratio can contribute to the retroposition of the mandible, as well as inhibition of the growth of the mandible in the sagittal direction.