Surface Electromyographic Evaluation of Nocturnal Masticatory Muscle Activity

Research has demonstrated a strong correlation between diurnal oral parafunctional activities and signs and symptoms of TMD. It is widely accepted that morning jaw pain is a result of nocturnal oral parafunctional activity, but to date, no cause and effect relationship has been demonstrated. This preliminary investigation used a portable EMG system to record all nocturnal masseter and ipsilateral temporalis muscle activity to a notebook computer. Twenty subjects were enrolled, ten into a morning jaw muscle pain group (JP) and ten into a non-pain control group (NJP). All subjects received a clinical examination to include the Cramo- Mandibular Index (CMI) and Symptom Severity Index (S SI). A baseline clinical measurement (BCM) was obtained by having each subject maximally clench three times and recording the average. Each subject was requested to wear the EMG electrodes for ten nights of data. The data were analyzed with EMG graphing software to determine the percent of time each subject spent below the 15%, 20%, 40%, 60% and 80% levels of the BCM. A 2- sample t-test was performed to compare the JP and NJP groups at each percent level, group BCM mean values, group mean ages, gender, mean recorded minutes and total recorded minutes. No statistically significant difference was found with any of the above parameters, including the percent of BCM levels. Based on this study the JP and NJP groups were not different with respect to the duration of nocturnal masticatory muscle activity and specific intensity levels. Difficulties were encountered with electrode pad disconnections possibly contributing to the excessive intra-group variability and inter-group overlap.Air Force Inst of Tech Wright-Patterson AFB OH is the author of 'Surface Electromyographic Evaluation of Nocturnal Masticatory Muscle Activity', published 2001 under ISBN 9781423527411 and ISBN 1423527410.