The Impact of Antioxidant Adjuncts on Periodontal Health in Type 2 Diabetes Patients: A Meta-Analysis

The bidirectional relationship between periodontitis and type 2 diabetes (T2D) underscores the need for adjunctive therapies to enhance nonsurgical periodontal therapy (NSPT). This meta-analysis evaluates the efficacy of antioxidants in improving periodontal and glycemic outcomes in T2D patients with periodontitis.

A systematic literature search was conducted using PubMed, Embase, Scopus, Web of Science, and Google Scholar, covering publications from 2015 to 2025. Antioxidants tested were melatonin, propolis, lycopene, ginger, vitamin C, omega-3 fatty acids (O3FAs), and grape seed extract. Outcomes (clinical attachment level [CAL], probing depth [PD], gingival index [GI], HbA1c) were analyzed using random-effects models (mean differences, 95% CIs). Risk of bias was assessed via the Cochrane criteria.

Eight randomized controlled trials (RCTs, n = 315) were identified. Adjunctive antioxidants significantly improved CAL (melatonin: SMD -2.28, 95% CI -3.01 to -1.56; propolis: SMD -3.83, -4.79 to -2.87) and PD (melatonin: SMD -2.40, -3.14 to -1.66; propolis: SMD -1.78, -2.44 to -1.11). Melatonin and propolis also reduced HbA1c (melatonin: SMD -2.28; propolis: SMD -3.83). Lycopene and ginger showed modest effects, while vitamin C and O3FAs had minimal impact. Evidence certainty was moderate for CAL/HbA1c and low for PD/GI.

Antioxidants, particularly melatonin and propolis, enhance periodontal and glycemic outcomes in T2D-periodontitis patients. Despite promising results, limitations include small sample sizes and heterogeneity. Larger RCTs are needed to optimize protocols.