Since both periodontitis and OSA are associated with systemic inflammations possibly involving similar pathways, the objective of this study was to compare the expression of pro-inflammatory cytokines IL-1β, IL-6, IL-17A, IL-33, and TNF-α simultaneously in saliva and GCF in patients with OSA as biomarkers associated with the periodontal condition and its clinical status. The gene discussed is IL33; the disease is periodontitis.