Random variation in the masseteric silent period after chin taps

Although the silent period duration has often been evaluated as a potential indicator of stomatognathic system dysfunction, there is still some uncertainty as to its normal biologic variation. This study investigated the subject variation in the silent period in a group of 22 young and healthy subjects under standardized conditions. Electromyographic recordings were obtained from the masseter muscle at 40% clenching after chin taps. Four different patterns of the silent period were recorded: one simple and three combined. Although the latencies of the early and late phases of depression were generally consistent, the results for duration were more variable and depended on the pattern of the silent period.