Effects of local anesthesia on bite force generation and electromyographic activity.

Maximum voluntary bite force has been used to evaluate functional changes following orthognathic surgery. It has been proposed by others that maximum voluntary bite force may depend, in part, on sensory input from the dentition. However, results from previous studies have shown contradictory effects of local anesthesia on bite force following anesthetization of the dentition. The purpose of this study was to investigate the effects of drug-induced local anesthesia on the generation of first molar bite force and electromyographic (EMG) activity in adults. Twenty normal adults (3 women, 17 men) were evaluated. Electromyographic activity was monitored from four muscles of mastication bilaterally, and bite force was concurrently recorded at the right and left first molars. Maximal and submaximal bite forces were then measured after sequential unilateral anesthetization of the right mandible and maxilla with 2% lidocaine containing 1:100,000 epinephrine. No statistically significant differences in bite force or integrated EMG levels were observed between the unanesthetized and anesthetized sides, nor on the anesthetized side at different levels of anesthesia.