Salivary cotinine and S100A8/A9 levels in children exposed to environmental tobacco smoke: a case-control study.

objectivesThis study aimed to evaluate salivary cotinine and S100A8/A9 levels in children exposed to ETS and to examine the relationship between exposure intensity and inflammatory biomarker expression. METHODOLOGY: This observational case-control study included 150 systemically healthy children aged 6-12 years. ETS exposure was determined using parent-reported questionnaires. Clinical parameters, including plaque index, gingival index, and probing pocket depth, were recorded. Unstimulated saliva samples were analyzed for cotinine, S100A8, and S100A9 using ELISA kits. Group comparisons were conducted using the Mann-Whitney U test, and correlations were assessed using Spearman's rank correlation coefficient. Statistical significance was set at p<0.05.

resultsETS-exposed and non-exposed groups did not differ significantly in age, sex, socioeconomic status, oral hygiene habits, or clinical periodontal parameters (p>0.05). However, salivary cotinine, S100A8, and S100A9 levels were significantly higher in ETS-exposed children (p<0.05). Cotinine demonstrated a moderate positive correlation with S100A8, while its correlation with S100A9 was weak and non-significant. Exposure intensity was positively associated with cotinine and S100A8 levels, but not with S100A9.

conclusionETS exposure in children is associated with early biochemical signs of inflammation, even in the absence of clinically detectable periodontal changes. Elevated salivary cotinine and S100A8 levels highlight the potential utility of salivary biomarkers for identifying subclinical effects of passive smoking. These findings underscore the importance of interventions aimed at reducing children's exposure to ETS to protect long-term oral health. Clinical trial registration: NCT06791707.