Sequential analysis of masseter activity patterns during chewing in healthy males.

The present study examined sequential changes in masseter activity patterns observed during chewing of four different agar samples in eight healthy young males. Two parameters, T(50) and D(50), were specifically used for evaluation of the activity patterns of individual bursts. Statistical significances were detected in regression coefficients (21.9% of 32 trials) and Spearman's rank correlation coefficients (28.1%) between the calculated T(50) values and chewing cycles, whereas no significant differences among the four agar samples were found. Three (I-III) types of activity patterns of masseter bursts during chewing sequences were classified by the D(50) values, which were derived from the T(50) values. The three types physiologically corresponded to incrementing (Type I), decrementing (Type III) and mixed discharge patterns (Type II). The classification of activity patterns suggested the usefulness of D(50) values in the sequential analysis of masseter activity patterns.