Altered electromyographic responses to emotional and pain information in awake bruxers: case–control study.

Objectives: This study aims to investigate how emotional information and pain-related information affect the activity of the masticatory muscles in participants with awake bruxism and controls. Material and methods: Different videos and texts, with positive, negative, and neutral valence or related to pain, were presented to a sample of university students, while their electromyographic (EMG) activity around the masseter muscle and their skin conductance were recorded. Two groups were selected, with 24 subjects each: one group of subjects with definitive awake bruxism (confirmed by posterior EMG activity) who also suffered from moderate jaw discomfort, and another group of subjects without bruxism. Results: The results demonstrated that the subjects with definitive awake bruxism displayed greater muscular activity when presented videos and texts with negative valence, especially when related to pain, than the non-bruxist group. Conclusions: This study supports the idea that persons with bruxism who also suffer moderate levels of jaw discomfort present greater bruxism activity when watching pain-related stimuli, and to a lesser extent when watching negative stimuli. Clinical relevance: The increased muscular activity induced by negative and pain-related information might contribute to pain exacerbation and perpetuation in persons with bruxism who suffer from discomfort. [ABSTRACT FROM AUTHOR]