Comparison of orofacial thermal sensitivity assessed with simple devices and sophisticated equipment

Background: Simple thermal devices providing reliable data are needed to detect somatosensory disturbances in non-specialized clinical settings. Currently, evidence is lacking about their use. Therefore, the aim was to compare the assessment of perceived thermal sensitivity/pain in healthy humans with a state-of-the-art thermotester and with simple inexpensive customized thermal aluminium devices.

Methods: Twenty healthy volunteers participated in the study. The infraorbital region and the tip of the tongue were tested with the Medoc Pathway thermotester and simple aluminium thermal devices, with temperatures varying between 5–50°C. A numerical rating scale (NRS) from 0–50–100 was used for rating the perceived thermal sensitivity/painfulness. A control experiment was performed with 10 of the participants to test the potential impact of temporal summation of thermal stimuli with the use of temperature ramps (Medoc) compared with static temperature (simple devices).

Results: In the original experiment, the scores from the thermotester stimulation were higher than the scores for stimulation with the simple thermal devices with mean NRS differences between devices of 7.2 and 10.2 for the two tested regions. In the control experiment, the mean NRS differences decreased to −0.3 and 2.2, respectively.

Conclusions: Provided that temporal summation of the thermal stimuli was avoided, there were only minor differences in perceived thermal sensitivity/painfulness between the two different assessment methods at both test sites. Therefore, the simple thermal devices can be useful for assessment of thermal sensitivity in clinical settings without access to expensive sophisticated equipment. However, more sophisticated equipment is needed for threshold measurements.

Significance: This study indicates that simple thermal devices to some extent can be used in a comparable way with sophisticated thermal stimulators. Therefore, they can be useful in clinical practice, where access to further equipment is lacking.