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Aim: To examine, in a double-blind and placebo-controlled
crossover manner, the effect of topical application of capsaicin on
the alveolar mucosa with a battery of intraoral quantitative sensory
testings (QST) in 16 healthy volunteers. Methods: Thirty µL
of 5 mg/mL capsaicin or vehicle (control) was applied to a 3 3-
mm paper disk and applied to the alveolar mucosa under an oral
bandage. The subjects rated the perceived pain intensity on a 0 to
10 electronic visual analog scale (VAS) for 15 minutes. Quantitative
sensory testings were performed before and immediately
after the 15-minute application and consisted of assessments of
cold detection threshold, warmth detection threshold (WDT), cold
pain threshold, heat pain threshold (HPT), mechanical sensitivity
to single and repeated punctate mechanical stimulation with
von Frey filaments and to single and repeated brush stimulation
with a cotton swab, and detection and pain thresholds to electrical
stimulation of the alveolar mucosa and maxillary first premolar
tooth. Analysis of variance was used to test the data. Results:
Application of capsaicin caused moderate levels of pain (VASpeak
scores 5.0 ± 1.9) whereas the vehicle was practically painless
(VASpeak 0.9 ± 2.4). No significant effects of vehicle on QST could
be detected (P .143). In contrast, capsaicin application was
associated with significant decreases in WDT and HPT (P
.001). No other significant changes in QST were observed for capsaicin
application. Conclusion: The intraoral capsaicin pain model
is associated with signs of heat hyperalgesia, but not mechanical
hyperalgesia. Since the somatosensory sensitivity is not well characterized
in most orofacial pain conditions, mainly due to lack of
tradition and techniques, intraoral QST may provide a better
description of the somatosensory sensitivity and underlying mechanisms
in orofacial pain conditions. J OROFAC PAIN 2003;17:333–340.
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