Effects of 660 nm & 808 nm photo-biomodulation on S100A8/A9 in symptomatic pulpitis: a randomized controlled trial

Photobiomodulation (PBM) modulates inflammation and promotes tissue repair. S100A8/A9 is a neutrophil-derived calcium-binding heterodimer that acts as a pro‑inflammatory damage‑associated molecular pattern, serving as a biomarker of inflammation. This study aimed to evaluate the effects of PBM at 660 nm and 808 nm wavelengths on S100A8/A9 levels in pulp blood (PB) and gingival crevicular fluid (GCF) in patients with symptomatic irreversible pulpitis (SIP). Patients diagnosed with SIP were block-randomised into three groups: Group 1 received 660 nm PBM (n = 14), Group 2 received 808 nm PBM (n = 13), and Group 3 received sham irradiation (n = 8). PB and GCF samples were collected pre- and post-irradiation. Laser activation lasted 60 s, delivering energy densities of 17.26 J/cm² (660 nm) and 33.16 J/cm² (808 nm). S100A8/A9 levels were quantified via enzyme-linked immunosorbent assay (ELISA) and analysed using fold change from baseline, Spearman non-linear correlation analysis for age effects, Fisher's exact test, and Kruskal-Wallis tests (α = 0.05). There was inter‑individual variation in baseline S100A8/A9 levels in both PB and GCF. Baseline S100A8/A9 levels were higher in GCF than in PB at the individual level, with no age effect in PB, whereas GCF levels were lower in the 60-80‑year group than in the 45-59‑year group. PBM at 660 nm and 808 nm produced numerically greater fold increases in S100A8/A9 in PB and GCF than sham, particularly for 660 nm in older participants, but these effects did not reach the threshold for statistical significance. This study is the first clinical trial to explore the effect of S100A8/A9 expression in PB and GCF following a single PBM treatment at wavelengths of 660 nm and 808 nm. This pilot study demonstrated that S100A8/A9 can be detected in pulp blood and GCF from patients with SIP and may serve as a potential biomarker for PBM response, although no statistically significant differences were found. Given the cumulative and time-dependent nature of PBM effects, future research should investigate multi-dose protocols to better define its role in managing pulpal inflammation.