Palpation pain threshold: interexaminador reliability and validity in TMJ disorder

Palpation (PA) is the most widely used clinical method to assess muscle and joint pain in patients with temporomandibular disorder (TMD). There is evidence supporting a more precise assessment of pain threshold when, instead of the examiner's fingers, an algometer is used to apply pressure over an area. Objectives: a) compare inter-examiner reliability of determining PA and pressure pain threshold (PPT) of the temporomandibular joint (TMJ) and the masseter and temporal muscles; b) assess differences in the sensitivity of the two techniques in symptomatic and asymptomatic patients; and c) evaluate the validity of the test for discriminating between TMD patients and non-TMD patients through evaluation of sensitivity, specificity and positive predictive value. Methods: eighty subjects (age range twenty-fifty years) were examined and distributed in two groups: Group 1 consisted of forty TMD patients with muscular and joint pain selected by RDC/TMD Axis I; and group 2 (control) with forty asymptomatic individuals. Training and calibration were provided for examiners prior to testing. Results: showed statistically significant differences (p < 0.001), for PA and PPT among TMD patients compared with the control group for all points of muscle and joint evaluation. Mean reliability values for PPT were 0.64 and 0.78 (intraclass correlation coefficients) for patients and control, respectively. Lower reliability was found for palpation with mean values of 0.59 and 0.75 for patients and controls respectively. Higher reliability values were found for masseter and temporal muscles and lower for the lateral pole of TMJ. The results also showed acceptable specificity values (above 0.90), although sensitivity had low values for most of the points assessed. Conclusions: the results demonstrated that the tests in isolation showed validity in discriminating the subjects of the control group, however, they were inefficient for the diagnosis of TMD patients.