Objective: To evaluate associations between pressure-pain sensitivity (PPS) measured before and at the time of developing TMD.
Methods: In the OPPERA prospective cohort study, 2,737 community-based adult volunteers, who did not have TMD when enrollled, were followed for up to 5.2 years, during which time 260 developed examiner-verified TMD. For this nested case-control study of TMD incidence, pressure pain thresholds, measured using a pressure algometer at trapezius and lateral epicondyle, were recorded at baseline and follow-up in three groups: a) 260 incident cases of examiner-confirmed clinical TMD; b) 149 incident cases of subclinical TMD (people who developed TMD symptoms but who did not have clinical TMD when re-examined); c) 204 controls who developed neither TMD symptoms nor clinical TMD during follow-up. Threshold values were transformed to negative-z-scores to produce PPS measures that were used in generalized logit regression models to estimate incidence odds ratios and 95% confidence limits (95%CLs) for development of clinical- and subclinical-TMD.
Results: PPS at baseline was not associated (P>0.12) with development of either clinical- or subclinical-TMD. Neither was PPS measured concurrently at follow-up associated with onset of subclinical TMD (P>0.61). However, PPS measured concurrently at follow-up was strongly associated with onset of clinical TMD (trapezius PPS OR=2.32, 95%CL=1.84, 2.93; lateral epicondyle PPS OR=1.78, 95%CL=1.41, 2.26).
Conclusions: Incidence of clinical TMD was associated with heightened PPS at the time of clinical TMD onset, but not before. Incidence of subclinical symptoms of TMD was unrelated to PPS, either before or at the time of symptom onset. In these adults, heightened PPS appears to occur in conjunction with development of clinical TMD, but does not contribute to risk of its development.