Type of correlation between bite force and EMG activity of the temporalis and masseter muscles during maximal and submaximal clenching

Abstract

Introduction: Maximal bite force is an important determinant of masticatory function and is essential for the estimation of dental status. Bite force is usually measured by gnathodynamometry. Aim: The aim of the study was to investigate the type of correlation between the electromyographic activity of the masticatory muscles and the bite force during simultaneous measurement and to evaluate the use of EMG activity as an option for indirect determination of the bite force. Materials and methods: The study included 68 people (33 men and 35 women) with a mean age of 18.4±6.1 years. The bite force and the sEMG were measured in all 68 subjects consecutively on the right and the left side during maximal (1) and submaximal (2/3 and 1/3) clenching. Statistical analysis was performed by IBM SPSS Statistics, version 23.0. Results: EMG activity and maximal bite force values did not show significant differences on the left and right side. Linear relationship was found for the association bite force: EMG activity for the masseter muscle during maximal and submaximal (2/3) clenching, while for 1/3 clenching force the association was lost. For the temporalis muscle, this relationship was linear for the left side during maximal and submaximal 2/3 clenching and non-linear for the right side. During 1/3 clenching, the linearity was lost on both left and right sides. Conclusions: The masseter muscle shows stable linear relationship between BF and EMG on both sides and can be considered reliable for indirect estimation of the bite force by measuring the EMG potentials. During low occlusal forces (1/3) the linearity of both masseter and temporalis muscles is decreased or lost.