Comparative Effect of Non-surgical Versus Surgical Therapy for Stage III/IV Periodontitis: A Retrospective Cohort Study

INTRODUCTION AND AIMS: Periodontitis is a major cause of tooth loss and a persistent challenge in clinical management. Although both non-surgical periodontal therapy (NSPT) and surgical periodontal therapy (SPT) are widely used for advanced periodontitis (Stages III/IV), their long-term comparative effectiveness in Chinese patients remains not well established. This retrospective study aimed to compare the clinical efficacy of NSPT versus SPT and to identify predictors of long-term treatment success. MATERIALS AND METHODS: This retrospective study included 2982 patients who received NSPT and 212 patients who underwent SPT, all diagnosed with stage III/IV periodontitis. Participants had a baseline periodontal evaluation and at least one re-evaluation between April 2017 and September 2022. Clinical parameters including probing depth (PD), clinical attachment loss (CAL), and bleeding on probing (BOP) were retrieved from a hospital-based electronic periodontal record system. Statistical analyses included independent t-tests, linear regression, and multilevel models, adjusted for age, sex, smoking, and follow-up compliance. RESULTS: Over a mean follow-up of 1.56 years, patients receiving SPT demonstrated significantly greater reductions than NSPT in PD (1.16 ± 1.06 versus 0.77 ± 0.81 mm), CAL (0.97 ± 1.13 versus 0.68 ± 0.90 mm), and BOP% (0.28% ± 0.27% versus 0.23% ± 0.29%) (all P < .01). However, this therapeutic advantage of SPT diminished with longer follow‑up (>3 years). Regular supportive periodontal care was consistently associated with improved clinical outcomes, regardless of whether intervention was SPT or repeated NSPT. CONCLUSIONS: In a large Chinese cohort with advanced periodontitis, SPT provided superior short-term clinical improvements compared to NSPT. However, long-term outcomes depend on sustained maintenance care. These findings highlight that successful periodontal management relies on both patient compliance and clinician awareness of the long-term value of NSPT. CLINICAL RELEVANCE: SPT offers superior short-term outcomes, while NSPT with maintenance achieves comparable long-term stability. Long-term success depends more on maintenance adherence than initial therapy.