Orofacial Thermal Thresholds: Time-Dependent Variability and Influence of Spatial Summation and Test Site

Aim: To investigate time-dependent variability and influence of test site and stimulation area size on intraoral cold detection, warmth detection, and heat pain thresholds. Methods: Thirty healthy volunteers (15 women and 15 men) participated. Six extra- and intraoral sites were examined, and cold detection, warmth detection, and heat pain thresholds were measured. Time variability and influence of spatial summation were also studied at one site-the tip of the tongue-three times over a 6-week period. One-way ANOVA for repeated measures and paired sample t test compared mean values and SD within and between sites for all thresholds. Results: Several between-site differences were significant (P .05). Lowest intraoral thresholds for all stimuli were measured at the tongue site, and at the tongue, thresholds for warmth detection and heat pain, but not cold detection, decreased with increasing size of stimulation area (P .05). Overall, thresholds at the tongue site varied nonsignificantly over time (P > .05). Conclusion: Test site affects orofacial thermal thresholds substantially, whereas time variability and spatial summation on the tongue appear to be modest. Keywords: facial pain, neuropathic pain, quantitative sensory -testing, reliability, thermal thresholds