Increased Pain Sensitivity to Intraoral Capsaicin in Patients with Atypical Odontalgia

Aims: To use 2 well-characterized stimuli, the intraoral capsaicin model and the “nociceptive-specific” electrode, to compare super-ficial nociceptive function between patients with atypical odontal-gia (AO) and matched healthy controls. Furthermore, the authors aimed to describe the sensitivity, specificity, and positive predictive values (PPV) of the techniques if group differences could be estab-lished. Methods: Thirty-eight patients with AO and 27 matched healthy controls participated in this study. Thirty microliters of 5% capsaicin was applied to the gingiva on the left and right sides of all participants as a pain-provocation test. The participants scored the capsaicin-evoked pain continuously on a 0-to-10 visual analog scale (VAS). Furthermore, individual electrical sensory and pain thresholds to stimulation with a ”nociceptive-specific” elec-trode on the facial skin above the infraorbital or mental nerve were determined. Results: AO patients had higher VAS pain scores for capsaicin application than healthy controls (ANOVA: F > 4.88; P < .029). No differences between the painful sides and the nonpainful sides of the patients were found (ANOVA: F < 1.26; P＞.262). No main effects of group or stimulation side on the elec-trical sensory and pain thresholds were detected (ANOVA: F < 0.309; P > .579). Sensitivity was 0.51; specificity, 0.81; and PPV, 0.77 when a VAS value of ≥ 8 for capsaicin-evoked pain was used. Conclusion: AO patients show increased sensitivity to intraoral capsaicin but normal sensitivity to “nociceptive-specific” electrical stimulation of the face in an area proximal to the painful site. The use of the intraoral pain-provocation test with capsaicin as a pos-sible adjunct to the diagnostic workup is hampered by the only moderately good sensitivity and specificity.

atypical odontalgia; capsaicin; neuropathic pain; trigeminal pain

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