An algometer for intraoral pain tolerance measurements

An algometer was developed to provide a variable probing force (0-200 g force) which could be used intraorally. This algometer consisted of an autoclavable probe handpiece attached to an optical encoder, which recorded probing force to a computer when a button was pressed. The probe handpiece included a 0.40 mm diameter hemispherical tip which was placed in contact with the experimental site. The probe tip was pressed against the tissue with increasing force until the subject pressed the button, at which point the pain tolerance (PT) value was recorded by the computer. Intraoral soft tissue, PT values were obtained from nine healthy adult subjects during 6 weekly visits to determine the reproducibility of PT measurements. Five gingival sulcus sites and three gingival surface sites, all adjacent to the maxillary premolars constituted the experimental area. The reproducibility of PT values using the force stimulus from the algometer was evaluated using interclass correlation coefficients (R) for each of the eight sites. Visits 1 and 2 were training and calibration visits. Visits 3 through 6 were experimental visits. The R values ranged from 0.40 to 0.79 when data from all six visits were included. R values for Visits 3 through 6 were 0.63-0.97 indicating good to excellent correlation after subjects became familiar with the procedure. A complete repeated measures analysis of variance (ANOVA) showed no significant interaction between site and visit. Duncan's multiple range test was used to compare sensitivity across the eight sites. The results indicated that the three most anterior sites were significantly (P < 0.05) more sensitive than four of the posterior sites. When the sites were grouped into: (1) gingival surface sites; (2) mid-facial sulcus sites; and (3) interproximal sulcus sites, no significant differences were found in their PT values. The algometer is well suited for intraoral investigations because of its precision, computerized data entry and easily positioned, autoclavable handpiece. This new algometer may be useful for sensory and pain studies for other parts of the body.