Application of a new palpometer for intraoral mechanical pain sensitivity assessment

To investigate the reliability and magnitude of intraoral mechanical pain sensitivity by using a palpometer with add-on devices with different physical properties.

Sixteen healthy volunteers participated. Three palpometers (0.5, 1.0, and 2.0 kg) were used. Add-on devices were put on the circular metal stamp of the palpometer. Four diameters (3, 4, 5, and 10 mm) and two shapes of the rubber-top (flat and round) of the add-on devices were tested at each force level, ie, a total of 24 combinations. Participants were stimulated at the gingival mucosa around the maxillary central incisors and first molars on both sides by using the palpometers in randomized order. Participants rated perceived stimulus intensity on a 0-50-100 numerical rating scale (NRS). Ten volunteers were examined twice on the same day and recalled for a second session for assessment of within- and between-session reliability. Intraclass correlation coefficients were calculated for reliability measures, and NRS scores were analyzed with analysis of variance.

Reliability of NRS scores was excellent (interclass correlation coefficients 0.76 to 0.99). Analysis of NRS values corrected for pressure level revealed that there were main effects of site (P = .006), force (P < .001), size (P < .001), and shape (P < .001) but not side (P = .051).

Reliability of intraoral novel palpometer measures of pressure sensitivity was excellent, and sensitivity to pressure stimulation was dependent on the applied force and physical properties of the add-on device. The study indicated that semi-quantitative assessment of intraoral mechanical sensitivity is feasible and could be applied in further studies on different intraoral pain conditions.