Intrarater Reliability of Intraoral Pressure Pain Threshold (PPT)

Aim: Determine the intrarater reliability coefficient of pressure pain threshold (PPT) measurements and compare the results with reliability coefficients for the mean of three measurements, which is accepted protocol. Methods: Sixteen subjects were evaluated; four subjects suffer from Atypical Odontalgia (AO) and twelve were pain-free controls. Thirteen females and three males were included in the study with mean age of 41.9 ± 11.5 years. PPT measurements were obtained using a pressure algometer with a 4.8 mm diameter round intraoral tip applied at a target rate of 50 Kp/s. The 4 anatomical locations tested, in randomized order, were the maxillary and mandibular gingival apical and mesial to the first premolar bilaterally. Intrarater reliability was determined for 4 raters measuring PPT in 4 quadrants and assessing each location three times. The resulting 16 reliability coefficients (4 raters x 4 quadrants) were calculated as intraclass correlation coefficients (ICC) based on one-way ANOVA. The ICCs were compared with another set of 16 ICCs based on the same data but using the mean of the three measurements performed by each rater. The magnitude of the ICCs was compared using accepted guidelines that suggest 0.75 as the threshold for excellent reliability. Results: The 16 quadrant-rater ICC combinations for single PPT measurements had a mean of 0.86. Only once did the ICC not reach “excellent” reliability threshold with a value of 0.74. The 16 quadrant-rater ICC combinations for the mean measurements per rater were only slightly higher, with a mean value of 0.95 and a minimum of 0.89. Conclusion: Intrarater reliability of PPT measurement seems to be sufficiently high when performed as a single measurement on the gingiva adjacent to premolars compared with the standard method of using the mean of 3 measurements.