Effect of non-surgical periodontal therapy on the salivary levels of IL-18 and IL-35 in patients with periodontitis

Background. Periodontal disease is the most prevalent chronic inflammatory condition that can cause the destruction of supporting periodontal tissues. It has been hypothesized that while the synthesis of pro- inflammatory cytokines causes tissue destruction and disease progression, anti-inflammatory cytokine production can result in protective immunity. The balance of inflammatory cytokines is central to the immunoregulation of the disease. Objectives. The aim of the study was to assess and compare the salivary levels of interleukin (IL)-18 and IL-35 in subjects diagnosed with gingivitis, periodontitis, and healthy individuals. Additionally, the study sought to evaluate the difference in the concentration of IL-18 and IL-35 after non-surgical periodontal therapy (NSPT) in subjects diagnosed with periodontal disease. Material and methods. A total of 69 individuals were divided into 3 groups: healthy (group 1; n = 23); gingivitis (group 2; n = 23); and stage II periodontitis (group 3A; n = 23). Saliva samples were obtained from each participant at baseline and, in the periodontitis group, at baseline and 12 weeks after NSPT (group 3B; n = 23). Probing pocket depth (PD), bleeding on probing (BoP), gingival index (GI), and clinical attachment level (CAL) were recorded and IL-18 and IL-35 levels were analyzed using an enzyme-linked immunosorbent assay (ELISA). Results. The mean salivary level of IL-18 was significantly higher in the gingivitis group compared to the other groups (p < 0.05), whereas the mean IL-35 level was significantly higher in the healthy group compared to the other groups (p < 0.05). Twelve weeks after NSPT, the periodontitis group demonstrated a statistically significant difference in cytokine levels, characterized by a decline in the IL-18 concentration (229.63 +/- 49.35 pg/mL) and an increase in the concentration of IL-35 (29.47 +/- 17.88 pg/mL). Conclusions. In the present study, a significant difference in the salivary levels of IL-18 and IL-35 before and after NSPT was observed. Therefore, these cytokines could serve as potential inflammatory biomarkers.