HMOX1 and periodontitis: OBJECTIVES: This study aimed to evaluate total oxidant status (TOS), total antioxidant status (TAS), oxidative stress index (OSI), arylesterase (ARE), heme oxygenase-1 (HO-1), and nuclear factor erythroid 2–related factor 2 (NRF-2) levels in saliva and serum samples of individuals with Stage III Grade B periodontitis, and to assess their relationship with disease activity and diagnostic potential in the pathogenesis of periodontitis.