Influence of pressure rates on the reliability of a pressure threshold meter.

The relationship between the rate of pressure applied over the masseter muscle and the pressure pain threshold was studied with the aid of an algometer (pressure threshold meter, PTM) connected to a stopwatch. Twenty consecutive patients with various degrees of craniomandibular dysfunction were included in the study. In 10 of the patients, the belly of the right superficial masseter muscle was recorded with the algometer 10 times using different pressure rates arbitrarily and unsystematically ranging from low to high values. The correlation between pressure rate and the PTM value was high. An increased pressure rate increased the PTM value (mean regression coefficient b = 0.70). A PTM value range of 0.5 kg/cm2 was found to correspond to a pressure rate range of 0.50 kg/cm2/s. In the remaining 10 patients, repeated recordings of the same site with a constant pressure rate did not influence the PTM value significantly.