Clinical Efficacy of Photodynamic Therapy and 1% Metformin Gel as Adjuncts to Scaling and Root Planing in the Treatment of Periodontitis: A Randomised Clinical Trial

Abstract

Introduction: Photodynamic Therapy (PDT) utilises lightactivated Photosensitisers (PSs) to generate Reactive Oxygen Species (ROS) disrupting bacterial biofilms and eliminating pathogens with minimal toxicity. Metformin enhances bacterial clearance, suppresses Lipopolysaccharide (LPS)- induced inflammation, and stimulates human Periodontal Ligament Fibroblasts (hPDLFs) to promote tissue repair and regeneration. Aim: To evaluate the efficacy of Photodynamic Therapy (PDT) and 1% Metformin Gel (MG) as adjuncts to Scaling and Root Planing (SRP) in managing Stage I/II Grade A/B Periodontitis. Materials and Methods: This clinical trial was a split-mouth, double-blind randomised controlled, single-centre study. Conducted in the Department of Periodontics Sree Sai Dental College and Research Institute, Srikakulam, Andhra Pradesh, India over 6 months from April 2025 to September 2025. The study included 25 systemically healthy individuals aged 18- 60 years. Participants were allocated into three treatment groups: SRP + PDT (Group I), SRP + 1% MG (Group II), and SRP alone (Group III). Clinical parameters assessed were Oral Hygiene Index-simplified (OHI-S), Plaque Index (PI), Gingival Index (GI), Sulcus Bleeding Index (SBI), Probing Pocket Depth (PPD), and CAL at baseline and at one, three, and six months. Statistical analysis was performed using Statistical Packages of Social Sciences (SPSS) version 23.0. Data were expressed as mean±Standard Deviation (SD). Intergroup comparisons were carried out using Kruskal-Wallis Analysis of Variance (ANOVA) and ANOVA as appropriate. Intragroup changes over time were analysed using Friedman ANOVA to identify significant differences. Results: The study population had a mean age of 29.92±10.44 years and comprised 13 males and 12 females. All three groups demonstrated highly significant intragroup improvements (p<0.0001) in OHI-S, GI, PI, SBI, PPD, and CAL over six months, confirming the effectiveness of SRP. Intergroup comparisons showed no significant differences in OHI-S, GI, PI, or SBI (p=1.00), indicating comparable control of plaque and inflammation. Group I (PDT+SRP) exhibited the greatest reductions in PPD, with significant improvements from baseline to three months (p=0.014*) and six months (p=0.045*), followed by stabilisation between three and six months (p=0.741). A similar pattern was observed for CAL, with Group I demonstrating superior gains compared with Group II and III. Overall, PDT resulted in greater pocket depth reduction and attachment gain, likely due to its antimicrobial and biofilm-disruptive properties, whereas MG showed relatively limited sustained efficacy. Conclusion: All three treatment modalities showed statistically significant intragroup improvements (p<0.0001) in all clinical parameters over six months, confirming the effectiveness of SRP. Intergroup comparisons revealed no significant differences in plaque and gingival indices (p=1.00). However, the PDT+SRP group demonstrated statistically significant reductions in PPD and gains in CAL at three and six months (p<0.05), followed by stabilisation, indicating an early therapeutic plateau. Overall, while all treatments were effective, PDT provided a statistically significant adjunctive benefit in improving pocket depth and attachment levels.