Effectiveness of Omega-3 Fatty Acids as an Adjunct to Scaling and Root Planing in Periodontitis: A Meta-Analysis of Randomized Controlled Trials.

BACKGROUND: Periodontitis is a chronic inflammatory disease driven largely by a dysregulated host immune response to bacterial biofilm. Omega-3 polyunsaturated fatty acids have anti-inflammatory and pro-resolving properties and have been proposed as an adjunct to scaling and root planing (SRP), but findings across individual trials remain inconsistent. This systematic review and meta-analysis aimed to evaluate the clinical efficacy of adjunctive omega-3 fatty acids compared with SRP alone or SRP plus placebo in patients with periodontitis. METHODS: A systematic search of PubMed, Scopus, Cochrane Library, grey literature and Google Scholar was conducted in accordance with PRISMA 2020 and Cochrane Handbook guidelines. Randomized controlled trials comparing SRP with adjunctive omega-3 supplementation to SRP alone or SRP plus placebo were included. Probing pocket depth (PPD) and clinical attachment level (CAL) were pooled as mean differences (MD), given that these outcomes were measured in the same unit (millimetres) across studies, while gingival index (GI), bleeding on probing (BOP) and plaque index (PI) were pooled as standardized mean differences (SMD), reflecting differing measurement scales. A random-effects model (Restricted Maximum-Likelihood method) was used, with heterogeneity quantified by the I2 statistic. Two sensitivity analyses were performed for each outcome: a leave-one-out analysis and a separate analysis excluding the one study whose data were converted from medians and interquartile ranges. Certainty of evidence was assessed using GRADE. RESULTS: Fifteen randomized controlled trials met the inclusion criteria. Adjunctive omega-3 significantly reduced PPD (15 studies, n = 617; MD = -0.43 mm; 95% CI -0.68 to -0.18; I2 = 92%) and improved CAL (12 studies, n = 514; MD = -0.47 mm; 95% CI -0.76 to -0.18; I2 = 89%). Significant benefits favouring omega-3 were also found for GI (7 studies, n = 297; SMD = -0.59; 95% CI -1.09 to -0.09; I2 = 76%), BOP (7 studies, n = 318; SMD = -0.95; 95% CI -1.60 to -0.31; I2 = 86%) and PI (9 studies, n = 407; SMD = -0.34; 95% CI -0.66 to -0.02; I2 = 60%). Both sensitivity analyses confirmed the direction and statistical significance of all pooled estimates. Certainty of evidence, assessed by GRADE, ranged from very low to low across outcomes. CONCLUSION: Adjunctive omega-3 fatty acid supplementation was associated with statistically significant improvements in PPD, CAL, GI, BOP and PI compared with SRP alone or SRP plus placebo. However, given the very low to low certainty of the underlying evidence and the substantial heterogeneity across included trials, these findings should be interpreted with caution, and omega-3 supplementation should currently be regarded as a supportive adjunct rather than a substitute for conventional periodontal therapy pending higher-certainty evidence from standardized trials.