IL6 and obstructive sleep apnea syndrome: To elucidate the association between OSA and periodontitis, this study compared the salivary and gingival crevicular fluid (GCF) concentrations of five pro-inflammatory cytokines (IL-1β, IL-6, IL-17A, IL-33, and TNF-α) in patients with and without OSA and their association with periodontal condition.