Salivary Levels of S100A8, S100A9 and S100A8/9 in Periodontal Health and Disease: A Cross-sectional Study

Introduction: Damage Associated Molecular Patterns (DAMPs) can initiate and amplify immune responses and can play an important role in the sustenance and progression of periodontal diseases. S100A8, S100A9 and their heterodimer, S100A8/9, are DAMPs or alarmins currently being evaluated for their potential as biomarkers in periodontal diseases. Aim: To quantify and compare salivary levels of S100A8, S100A9 and S100A8/9 in periodontal health, gingivitis or stage 1 periodontitis and stages 3 or 4 periodontitis. Materials and Methods: A cross-sectional analytical study was carried out in the Department of Periodontics, Saveetha Dental College and Hospital, Chennai, India, from December 2022 to February 2023. Periodontal examination and saliva sample collection were done for sixty-eight consecutively enrolled subjects who met the inclusion and exclusion criteria. Study subjects were categorised as group 1, which comprised participants with clinical periodontal health (n=20), group 2, subjects with gingivitis or stage 1 periodontitis (n=20), and group 3, which included patients with stages 3 or 4 periodontitis (n=28). Detailed clinical examination and periodontal charting were done in all study subjects. Saliva samples were processed and stored at -80 degrees C, and enzyme-linked immunosorbent assay was done to quantify S100A8, S100A9 and S100A8/9. Data were analysed using International Business Machines (IBM) Statistical Package for the Social Sciences (SPSS) software version 25.0. Salivary levels of S100A8, S100A9 and S100A8/9 were expressed as mean and standard deviation values. Mean values of the three salivary proteins were compared using the non parametric Kruskal-Wallis test. Bonferroni adjusted pairwise comparisons were also done. The p-values less than 0.05 were considered statistically significant. Results: The mean age of study participants was 38.97 +/- 7.62 years. Salivary levels of S100A8 were 41.34 +/- 14.34, 141.95 +/- 185.25 and 901.37 +/- 65.60 pg/mL in groups 1, 2 and 3, respectively. A statistically significant difference was present among the three groups for mean salivary levels of S100A8 (p-value<0.001). Pairwise comparisons showed that salivary S100A8 values in group 3 were significantly higher than the values observed in clinical health (group 1) (p-value<0.001) and those seen in the gingivitis or stage 1 periodontitis group (group 2) (p-value<0.001). Mean salivary levels of S100A9 and S100A8/9 did not show any statistically significant differences between the groups. Conclusion: There is an altered expression of S100A8, S100A9 and S100A8/9 in periodontal diseases compared to clinical health. Salivary levels of S100A8 are markedly different in cases of advanced periodontal destruction than in periodontal health and early stages of periodontal disease. Salivary S100A8 merits potential as a biomarker for periodontal diseases.