Journal of oral rehabilitation
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The present study evaluated the reproducibility of the late exteroceptive suppression period (ES2) and of pain perception. The surface electro-myogram (EMG) was recorded from the left masseter muscle in 12 males and 12 females (22-31 year). Thirteen fixed stimulus intensities from 5 to 25 mA with 2.5 mA intervals were applied at random to the left mental area, and stimulus-response (S-R) curves were built for each subject. ⋯ The reflex threshold, the reflex appearance and saturation level showed a significant decrease from the first to second session (P < 0.05), while the pain threshold was significantly higher during the second session (P < 0.01). By contrast, a good reproducibility was found for the maximum duration and suppression degree of ES2. Consequently, if S-R curves would be used to study the relation between the ES2 parameters and stimulus intensity in normal subjects for their applicability in clinical conditions, maximum duration and maximum suppression degree should be focused upon, in order to avoid session and gender effects as confounding factors.