Maximal bite forces in healthy young adults as predicted by surface electromyography

To assess the repeatability of maximal bite force estimates as obtained by submaximal electromyographic-force relationships performed simultaneously and symmetrically in both sides of the mouth. The protocol could be used in a clinical context to obtain indicative values for the occlusal loads to be resisted by the prosthetic reconstructions.

Ten young healthy subjects performed; (1) a maximum voluntary clench (MVC) directly on their occlusal surfaces; (2) four simultaneous recording of submaximal bite forces (98, 196, 304 and 392 N on two transducers positioned on the left and right first mandibular molars) and surface EMG potentials of the masseter and temporalis anterior muscles. The actual force peak value was recorded. For each subject, a linear regression was run between the simultaneous bite force and EMG submaximal values recorded in the four tests. Using the EMG potentials obtained during the MVC tests, the best fitting line was used to estimate a maximum bite force. Two independent recordings were made by each subject (2 week interval) and analyzed by correlation analysis, paired Student's t-test, and Dahlberg statistic.

Significant linear relationships were found between bite force and EMG potentials (p<0.01). The two series of indirect estimates of maximal bite force were correlated (r=0.626) without systematic differences (Student's t, p>0.01). Dahlberg statistic was 115.37 N (approximately 36% of the total variance of the group).

Simultaneously recorded submaximal bite forces and surface EMG potentials of mandibular elevator muscles had a linear relationship. The estimates of maximum bite force were repeatable on a short-term basis (2 weeks). The method limited the disadvantages of bite force recordings, and it could be used to obtain indicative values for the occlusal loads to be resisted by the prosthetic reconstructions.