Reliability and Validity of a Pressure Threshold Meter in Recording Tenderness in the Masseter Muscle and the Anterior Temporalis Muscle

The reliability and validity of an algometer pressure threshold meter (PTM) was evaluated on 45 individuals, 25 healthy volunteers and 20 patients with craniomandibular dysfunction. Tenderness upon palpation was measured at six points located on the masseter muscle, the anterior temporal muscle, and on the zygomatic arch. The validity of the PTM was evaluated by comparison of the PTM values obtained by one examiner with the finger palpation score obtained by another examiner (Part 1). A statistically significant correlation between PTM values and finger-palpation scores was found at all of the points recorded (p less than 0.05). A statistically significant difference between PTM values was obtained for the symptom-free group and the patient group. The reliability of the PTM was evaluated at six points by repeated recordings at each marked point (Part 2). High reliability coefficients (r = 0.79-0.94) were found at all the points. The study also showed that if the points were located with a certain inaccuracy (1.0 mm less than x less than 2.6 mm), the reliability coefficients were still of the same magnitude. The PTM can be recommended for evaluation of pressure pain thresholds in the masticatory system in clinical and experimental studies.