Chewing in Temporomandibular Disorder Patients: An Exploratory Study of an Association With Some Psychological Variables

Aims: To compare kinematic parameters (ie, amplitude, velocity, cycle frequency) of chewing and pain characteristics in a group of female myofascial temporomandibular disorder (TMD) patients with an age-matched control female group, and to study correlations between psychological variables and kinematic variables of chewing. Methods: Twenty-nine female participants were recruited. All participants were categorized according to the Research Diagnostic Criteria for TMD (RDC/TMD) into control (n = 14, mean age 28.9 years, SD 5.0 years) or TMD (n = 15, mean age 31.3 years, SD 10.7) groups. Jaw movements were recorded during free gum chewing and chewing standardized for timing. Patients completed the Depression, Anxiety, and Stress Scales (DASS-42), the Pain Catastrophizing Scale (PCS), the Fear of Pain Questionnaire-III (FPQ-III), and the Pain Self-Efficacy Questionnaire (PSEQ). Statistical analyses involved evaluation for group differences, and correlations between kinematic variables and psychological questionnaire scores (eg, depression, anxiety, stress) and pain intensity ratings. Results: Velocity and amplitude of standardized (but not free) chewing were significantly greater (P .05) in the TMD group than the control group. There were significant (P .05) positive correlations between pain intensity ratings and velocity and amplitude of standardized chewing but not free chewing. There were significant (P .05) positive correlations between depression and jaw amplitude and stress and jaw velocity for standardized but not free chewing. Conclusion: This exploratory study has provided data suggesting that psychological factors, manifesting in depression and stress, play a role in influencing the association between pain and motor activity. Keywords: anxiety, clinical pain, depression, jaw movement, -mastication, pain adaptation model, stress, temporomandibular disorders