Dentine hypersensitivity: is there both stimulus and placebo responses in clinical trials?

To determine whether application of a periodontal dressing stopped pain arising from dentine hypersensitivity, objectively assessed with evaporative and thermal stimuli and recorded with Visual Analogue Scale scoring (VAS).

22 subjects completed the single-centre, subject-blind, stratified, randomized, split-mouth study, with a minimum of two sensitive teeth, in at least two different quadrants, displaying a response of >or=30 mm with VAS to evaporative stimulus. One tooth in two different quadrants was identified and randomized to test or control groups. A dressing was applied to all the sensitive teeth in the test quadrant, and either side of the chosen sensitive tooth on the control side. The test teeth were then stimulated for hypersensitivity using evaporative stimuli and then using thermal stimuli.

Analysis showed that dressing application produced significantly greater reduction in pain (P<0.0001) compared with no periodontal dressing. Single application of a dressing to sensitive dentine provided 95% pain relief associated with thermal stimulus and 85% pain relief associated with evaporative stimulus.

Application of the dressing to sensitive teeth, dramatically reduced the pain of dentine hypersensitivity following tooth stimulation. When assessing subjects' response to pain-evoking stimuli, perception of pain appears to be altered by sensory factors, prompting a heightened pain response.