BACKGROUND: Matrix metalloproteinase-9 (MMP-9), total superoxide dismutase (T-SOD) and sirtuin (SIRT)-1 are interrelated molecules linked with oxidative stress and periodontitis pathogenesis which may have implications for both the diagnosis of periodontitis or efficacy of periodontal treatment. This study aimed to evaluate salivary and serum MMP-9, T-SOD, and SIRT-1 levels in stage 3 periodontitis patients (P-S3) following non-surgical periodontal treatment (NSPT). METHODS: Forty-nine subjects, comprising 17 healthy, 16 P-S3 Grade B (P-S3GB), and 16 P-S3 Grade C (P-S3GC) subjects, participated in the study. Clinical periodontal parameters, salivary and serum MMP-9, T-SOD and SIRT-1 levels were evaluated at baseline from all participants and at 3-months from periodontitis patients. Enzyme-linked immunosorbent assay (ELISA) was used to assess the levels of the biochemical parameters. RESULTS: All clinical periodontal parameters improved in both periodontitis groups (p <
0.05) after NSPT. In P-S3GB and GC groups, salivary levels of MMP-9 and T-SOD were higher than healthy controls (p <
0.05) and decreased following NSPT (p <
0.05). P-S3GC group had higher serum MMP-9 levels than the healthy ones (p <
0.05). Salivary SIRT-1 and serum T-SOD levels were similar among groups (p >
0.05). After NSPT, only in P-S3GB group, salivary SIRT-1 decreased, and serum T-SOD increased (p <
0.05). Salivary T-SOD and MMP-9 showed positive correlations with clinical parameters (p <
0.05). CONCLUSIONS: The study results suggest that MMP-9 and T-SOD are potential biomarkers for diagnosing P-S3GB and GC and evaluating the efficacy of NSPT. However, further research is necessary to validate these findings across all grades and stages of periodontitis. TRIAL REGISTRATION: This study was retrospectively registered on 13/02/2024 at Clinical trials.gov with the number NCT06255470.