A standardized system for evoking masseteric silent periods with decreased variance

Masseteric silent periods have been evoked in a group of normal subjects under a standardized system and under nonstandardized conditions. In the designed system, head position, electrode placement, bite force, tap force, direction of tap, and surface zone of tap force delivery were controlled. Analysis of data confirmed the hypothesis that standardization of the procedure for eliciting the silent period results in measurements of duration with decreased standard deviations and variances. In the present study, under the standardized system the SPD range of standard deviations was between 1.37 and 3.68 (mean 2.97) and the range of variances was between 1.89 and 13.54 (mean 8.85). The recorded low variability suggests a high degree of reproducibility of the system. High reproducibility and low variability of measurements are necessary if an accurate measure of silent period duration is to be achieved and used in the interpretation of diagnostic findings for craniomandibular disorders.