The Reproducibility of Muscle and Joint Tenderness Detection Methods and Maximum Mandibular Movement Measurement for the Temporomandibular System

The purpose of this study was (1) to evaluate the reproducibility of two masticatory muscle and joint tenderness detection methods; (2) to evaluate the reproducibility of maximum mandibular movement measurements; and (3) to investigate factors influencing examiner agreement. The tenderness assessment procedures involved application of a standard pressure for 2 seconds over four anatomically defined masticatory muscle sites, one control forehead site, and two temporomandibular joint sites on each side of the face. One technique utilized a pressure algometer (PAP), while the other technique required that a trained examiner apply pressure with the index fingertip (FPP). Seventy-two subjects (36 patients and 36 controls) were evaluted in a single-blind study design. Control subjects were matched for age, gender, and race with temporomandibular disorder subjects. Each subject was examined twice with each of the described methods in a randomized, fully balanced sequence by calibrated examiners. Tenderness levels were determined by the subject via self-report of pain upon pressure using a standard set of verbal descriptors. Maximum pain-free, active, and passive opening, and maximum active right and left lateral movements were measured using a millimeter ruler. Intraclass correlation coefficients (ICC) for the tenderness assessment methods ranged from 0.220 to 0.739 for the FPP method and from 0.391 to 0.880 for the PAP method. ICCs for mandibular movement measurement were much less variable, ranging from 0.59 to 0.68 for lateral movement and from 0.78 to 0.93 for opening movement. These results indicate good to excellent agreement between calibrated examiners for mandibular movement measurement and for tenderness assessment methods at two masseter (ie, superficial and deep) and the anterior temporalis sites. Only fair agreement was found for the middle temporalis and lateral TMJ capsule sites using these methods.