ESTIMATING HUMAN INCISAL BITE FORCES FROM THE ELECTROMYOGRAM BITE-FORCE FUNCTION

This study used the electromyogram (EMG)/force-function curve as a mea ns of estimating functional bite forces. Surface EMG recordings were m ade for the masseter and anterior temporalis muscles bilaterally in te n adults while incisal bite forces were measured using a force transdu cer embedded in custom-made hydroplastic bite blocks. Measurements wer e made for mouth openings of 15 and 30 mm. Each subject was first inst ructed to develop a maximum level of bite force, and then to develop b ite-force levels that corresponded to decreasing percentages of his or her maximum, from 90 to 10%, in 10% decrements. After the force measu rements had been made, each subject was instructed to incise various f ood substances. The power-density spectrum and r.m.s. power level were calculated for each sample. Maximum bite-force levels varied consider ably among the 10 subjects, ranging from a minimum of 2.5 kg to a maxi mum of 40 kg. For the subjects as a whole, estimated bite forces for t he different types of food ranged from 3.0 to 5.5 kg. This range was i ndependent of the subjects' maximum bite-force levels. Thus, bite forc es exerted to incise different foods probably depend more on the food than on the individual's bite capabilities. There was variability with in this range, although, as expected, bite forces were least for choco late and greatest for apple and toffee.