A pilot study of nocturnal temporalis muscle activity in TMD diagnostic groups of women

Background Temporomandibular disorder (TMD) incidences are believed to be related to parafunctional behaviors like teeth clenching. Objectives This pilot study aimed to (i) develop an automated clench-detection algorithm, and (ii) apply the algorithm to test for differences in nocturnal clenching in women with and without TMD. Methods Subjects gave informed consent to participate. Adult women were categorized using Diagnostic Criteria for TMD according to presence/absence (+/-) of both TM joint disc placement (DD) and chronic pain (P) into two groups (+DD+P, -DD-P) with 12 subjects each. Surface temporalis electromyography was recorded during oral tasks performed by subjects at two laboratory sessions. The data were used to characterize muscle activity per N of bite-force (μV/N) for each subject, develop the clench-detection algorithm and test its accuracy. Ambulatory surface temporalis electromyography was self-recorded by each subject over three nights and analyzed using the algorithm and bite-force (N) vs muscle activity μV/N calibrations. Bonferroni-adjusted homoscedastic t-tests assessed for significant between-group differences in clenching (p<0.05). Results Sensitivity, specificity, and accuracy of algorithm-detected laboratory clenches were all ≥96%. During self-recordings 95% of clenches had durations of <4 seconds and peak forces of <10 N in both groups. Mean clench durations were significantly longer (p=0.042) in +DD+P (1.9±0.8 seconds) than -DD-P subjects (1.4±0.4 seconds). Mean temporalis duty factors (%clench time/total recording time) were significantly larger (p=0.041) in +DD+P (0.47±0.34%) than -DD-P (0.26±0.22%) subjects. Conclusions Nocturnal temporalis muscle activities detected by a validated algorithm were longer per clench and recording time in +DD+P compared to -DD-P women. This article is protected by copyright. All rights reserved.