Self-reported oral parafunctions and pain intensity in temporomandibular disorder patients

Aim: To examine the relationship between different types of self-reported oral parafunctions and pain intensity in patients with temporomandibular disorders (TMD). Methods: Two cohorts of TMD pain patients, 1 comprising 303 patients and the other comprising 226 patients, completed a 12-item oral Parafunctions questionnaire as well as the Research Diagnostic Criteria Axis II questionnaire, which includes a characteristic pain intensity score (CPI). Relationships between oral parafunctions and CPI were examined; age and gender were controlled for. The effects of phrasing of the oral parafunction questions were also examined. For 1 cohort, the questions were directed at the mere occurrence of the parafunctions; in the other, the questions addressed the perceived stressfulness of parafunctional behavior to the jaw. Results: A principal component analysis of the responses to the questionnaires led to 3 factors (scales) in both cohorts: (1) a BRUX scale for bruxism activities; (2) a BITE scale for biting activities (eg, chewing gum, nails); and (3) a SOFT scale for soft tissue activities (eg, tongue, lips). Statistical significance was reached for 2 of the 6 relationships studied (P < .05), but with a very low explained variance (approximately 3.5%). Conclusion: No clinically relevant relationships were found between different types of self-reported oral parafunctions and TMD pain complaints.