Pain sensitivity and the development of temporomandibular disorders.

摘要

The pathophysiological processes that contribute to the development and maintenance of TMD are poorly understood. The aim of this study was to determine whether pain sensitivity and various psychosocial factors extracted from self-reported questionnaires, are predictive factors for the development of TMD. A prospective study on 244 initially pain-free females aged 18 to 34 years was conducted. Measures of pain sensitivity and questionnaire assessments of psychological state and trait were performed at baseline and repeated annually. Over the past 34 months, 16 subjects developed TMD. Subjects who developed TMD demonstrated significantly lower baseline pressure pain threshold at the wrist and masseter muscle when compared to control subjects who did not develop TMD. TMD subjects also had significantly higher levels of baseline anxiety and somatization than control subjects.; When the correlations among different pain modalities were investigated, it was found that they were significantly correlated, although the strength of the associations was weak to moderate. When each value of different pain measures was transformed into a Z-score, plotting the combined Z-scores of all pain measures revealed normally distributed Z-scores. By dividing the distribution into tertiles, it was found that a higher number of TMD subjects (8 out of 16) fell into the lowest tertile of the distribution compared to the other two tertiles. The combined pain sensitivity Z-scores also predicted clinically assessed facial muscle and joint pain sensitivity, as well as the levels of psychosocial distress and dysfunction. As for the long-term stability of different pain measures (i.e., two years), it was found that there was a long-term temporal stability of the various pain measures, especially for the measure of C-fiber thermal pain tolerance.; At their first annual follow-up appointments, pressure pain threshold assessed at the temporalis and masseter muscle, as well as the TMJ showed significant decreases relative to the previous year's baseline values for TMD subjects but not for controls. Collectively, these data suggest that individuals who develop TMD show altered processing of nociceptive information prior to and following the development of TMD.