An Efficacy of Photobiomodulation of 850 nm on Pain Reduction in a Human Oral Capsaicin Pain Model.

Abstract

Objective: The aim of this clinical trial was to evaluate the efficacy of photobiomodulation (PBM) to reduce oral pain initiated by capsaicin. Background: PBM has been used for pain reduction in oral regions; however, its clinical efficacy to alleviate burning sensations is still unknown. Methods: This clinical study was divided into two phases. There were 10 subjects in each phase. In Phase I, the burning sensation was stimulated using 0.05% in 95% ethanol capsaicin (prepared by the Faculty of Pharmaceutical Sciences, Khon Kaen University, Thailand) on filter paper and recorded with a 10-cm horizontal visual analog scale (VAS) every 1 min until the subject experienced no more pain. The area under the curve (AUC) of the graph between VAS and time was calculated. The washout period was 24 h. In Phase II, a crossover clinical trial was conducted in subjects who received the pain model as stated. Four interventions were included: (1) PBM before & after pain stimulation, (2) PBM before pain stimulation, (3) PBM after pain stimulation, and (4) Placebo. For PBM intervention, a single exposure of 850 nm Laser (AsGaAl; TOP 250 Soft Laser, Berkmed Medikal, distributed by Medical Innovation-MI, Istanbul, Turkey) with 0.10 cm2 spot size laser probe continuous wave at 1 W/cm2 and 30 J/cm2 for 30 sec was used. Results: In Phase I, there was no statistically significant difference (p = 0.09) between the average AUC of day 1 [55.63 (23.38)] and day 2 [48.99 (27.20)]. In phase II, there was no statistical difference (p = 0.20) of the average AUC among the interventions and the placebo; group 1 [56.24 (30.11)], group 2 [45.46 (45.46)], group 3 [64.15 (32.89)], and group 4 [58.59 (30.16)]. Conclusions: The human capsaicin model was suitable for a crossover design clinical trial. The PBM used in this study did not reduce oral burning sensations from capsaicin.