Effect of electromyogram biofeedback on daytime clenching behavior in subjects with masticatory muscle pain

Purpose: Although daytime clenching is believed to be one of the oral parafunctions leading to dental problems, a treatment strategy has not yet been devised. Electromyogram (EMG) biofeedback training was performed to ascertain its effect on the regulation of daytime clenching behavior. Materials and methods: Twenty subjects (mean age, 30.9 +/- 5.6 years) who had mild to moderate masticatory muscle pain with daytime clenching behavior were randomly divided into either a biofeedback group (BF) or control group (CO). Subjects were fitted with a hearing-aid-shaped EMG recording and biofeedback apparatus which was used to record EMG data under natural conditions from the temporal muscle, continuously for five hours on four consecutive days. EMG data on Days 1 and 4 were recorded without biofeedback as pre-test and post-test, respectively, and on Days 2 and 3, subjects in the BF group noticed their clenching behaviors via an alert sound from the EMG biofeedback apparatus. No alert sound was given for the CO group throughout the recording sessions. Results: There was no significant difference in the number of clenching events for five hours between the BF group (4.6 +/- 2.5) and CO group (4.6 +/- 0.9) on Day 1, however a significant decrease was found in the BF group between Day 1 (4.6 +/- 2.5) and Day 4 (2.4 +/- 1.7; P < 0.05). Conclusion: Daytime clenching was reduced in the short-term with the help of an EMG biofeedback system under natural circumstances. Further research is needed to confirm a long-lasting effect. (C) 2010 Japan Prosthodontic Society. Published by Elsevier Ireland. All rights reserved.