title: Parafunctional clenching, pain, and effort in temporomandibular disorders.
abstract: This study tested the hypotheses that (1) parafunctional clenching increases pain and can lead to a diagnosis of temporomandibular disorder (TMD) pain and (2) electromyographic (EMG) activity during parafunctional clenching is significantly and positively correlated with reports of pain. Fourteen individuals without TMD participated in 5 consecutive days of 20-min long EMG biofeedback training sessions of the left and right temporalis and masseter muscles. Subjects were randomly assigned to either a Decrease or Increase group and were instructed to maintain EMG activity below 2 microV or above 10 microV during training, respectively. Two Increase subjects and no Decrease subjects were diagnosed, by a blinded examiner, with TMD pain following training. Self-reported pain posttraining was significantly higher for the Increase group. Masseter EMG activity was strongly correlated with pain. Parafunctional clenching increases pain and can lead to a diagnosis of TMD in otherwise pain-free individuals. Pain reports are positively correlated with the activity of the masseter muscle.
authors.affiliation: Department of Dental Public Health and Behavioral Science, University of Missouri-Kansas City, Kansas City, Missouri, USA. glarosa@umkc.edu
authors.forename: Alan G
authors.initials: AG
authors.lastname: Glaros
authors.forename: Eric
authors.initials: E
authors.lastname: Burton
mesh_terms: D000328:Adult; D001676:Biofeedback, Psychology; D002012:Bruxism / Q000503:physiopathology*; D004576:Electromyography; D005157:Facial Pain / Q000209:etiology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008410:Masticatory Muscles / Q000503:physiopathology; D009119:Muscle Contraction; D010147:Pain Measurement; D011434:Proprioception; D013705:Temporomandibular Joint Disorders / Q000503:physiopathology*; D013997:Time Factors; D016896:Treatment Outcome