Local curcumin/turmeric-derived delivery adjunctive to scaling and root planing for periodontitis: a systematic review and meta-analysis

BACKGROUND: Locally delivered curcumin and turmeric-derived formulations have been proposed as adjuncts to scaling and root planing (SRP), but the evidence is difficult to interpret because trials differ by design, comparator, population, formulation and follow-up. METHODS: We searched PubMed, Embase, Scopus, Web of Science, CENTRAL, ClinicalTrials.gov, and other relevant sources from inception to 18 May 2026. Search terms covered curcumin, turmeric, curcuminoids, Curcuma longa, periodontitis, periodontal pockets, scaling and root planing, non-surgical periodontal therapy, and local or subgingival drug delivery. Two reviewers independently screened records, extracted data and assessed risk of bias using RoB 2. Random-effects meta-analyses were stratified by study design, comparator type and population, and certainty of evidence for the primary outcome was assessed using GRADE. RESULTS: The search identified 71 database records and 8 ClinicalTrials.gov registry records. Twenty-nine randomized or quasi-randomized clinical reports were included in the qualitative synthesis, and 27 reports contributed extractable PPD data to at least one quantitative analysis. In systemically healthy participants with inactive controls, adjunctive curcumin/turmeric-derived delivery was associated with modest PPD reduction in parallel-arm studies (6 studies; MD -0.67 mm, 95% CI -1.13 to -0.22; I2 = 79.6%) and split-mouth studies (15 studies; MD -0.46 mm, 95% CI -0.68 to -0.24; I2 = 87.5%). Prediction intervals crossed the null in both analyses, and the certainty of evidence for PPD reduction was rated as low because of risk of bias and inconsistency. Active-comparator analyses were highly heterogeneous and exploratory. CONCLUSIONS: Locally delivered curcumin/turmeric-derived formulations used adjunctively with SRP may provide a modest improvement in PPD reduction; however, the findings should be interpreted cautiously because of substantial heterogeneity and methodological limitations. The certainty and clinical applicability of the evidence remain limited by small trials, high heterogeneity, incomplete reporting, variable formulations and geographically clustered evidence. Current evidence does not establish dose-response, formulation superiority, safety, or replacement of chlorhexidine, antibiotics or other conventional antimicrobial agents. REGISTRATION: PROSPERO CRD420261333717, Registered on 6 March 2026.