title: Differential changes in gingival somatosensory sensitivity after painful electrical tooth stimulation.
abstract: We aimed to evaluate the effect of painful tooth stimulation on gingival somatosensory sensitivity of healthy volunteers in a randomized, controlled design. Thirteen healthy volunteers (six women, seven men; 28.4 ± 5.0 years) were included for two experimental sessions of electrical tooth stimulation: painful tooth stimulation and tooth stimulation below the sensory threshold (control). Eight of the human subjects participated in a third session without tooth stimulation. In all sessions, the somatosensory sensitivity of the gingiva adjacent to the stimulated tooth was evaluated with a standardized battery of quantitative sensory tests (QST) before, immediately after and 30 min after tooth stimulation. Painful tooth stimulation evoked significant decreases in warmth and heat pain thresholds (P < 0.001) as well as pressure pain thresholds (increased sensitivity) (P = 0.024) and increases in mechanical detection thresholds (decreased sensitivity) (P < 0.050). Similar thermal threshold changes (P < 0.019) but no mechanical changes were found after tooth stimulation below the sensory threshold (P > 0.086). No QST changes were detected in the session without tooth stimulation (P > 0.060). In conclusion, modest increased gingival sensitivity to warmth, painful heat and pressure stimuli as well as desensitization to non-painful mechanical stimulation were demonstrated after tooth stimulation. This suggests involvement of competing heterotopic facilitatory and inhibitory mechanisms. Furthermore, stimulation below the sensory threshold induced similar thermal sensitization suggesting the possibility of activation of axon-reflex-like mechanisms even at intensities below the perception threshold. These findings may have implications for interpretation of somatosensory results in patients with chronic intraoral pain.
authors.affiliation: Section of Clinical Oral Physiology, Department of Dentistry, HEALTH, Aarhus University, Vennelyst Boulevard 9, 8000, Århus C, Denmark, lene.hansen@odont.au.dk.
authors.forename: Lene
authors.initials: L
authors.lastname: Baad-Hansen
authors.forename: Shengyi
authors.initials: S
authors.lastname: Lu
authors.forename: Pentti
authors.initials: P
authors.lastname: Kemppainen
authors.forename: Thomas
authors.initials: T
authors.lastname: List
authors.forename: Zhenting
authors.initials: Z
authors.lastname: Zhang
authors.forename: Peter
authors.initials: P
authors.lastname: Svensson
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001703:Biophysics; D004558:Electric Stimulation / Q000009:adverse effects*; D005260:Female; D005881:Gingiva / Q000503:physiopathology*; D064368:Healthy Volunteers; D006801:Humans; D006930:Hyperalgesia / Q000503:physiopathology*; D008297:Male; D010146:Pain / Q000503:physiopathology*; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology*; D010812:Physical Stimulation / Q000009:adverse effects; D014070:Tooth / Q000294:innervation*; D055815:Young Adult