Effectiveness of oxidative therapies in mature oral biofilms: A systematic review and meta-analysis

Abstract

To evaluate the antimicrobial activity of oxidative therapies in disrupting and reducing mature oral biofilms (≥ 48 h) and to assess treatment effects across different oxidative modalities. A systematic review and meta-analysis were conducted following PRISMA 2020 guidelines. Twenty-three studies involving in vitro, in situ, ex vivo, and clinical models were included in the systematic review. To improve methodological homogeneity, the primary quantitative synthesis was restricted to in vitro studies with extractable numerical data. In situ, ex vivo, and clinical studies were synthesized narratively. Outcomes included percentage bacterial viability reduction and log₁₀ CFU reduction. Random-effects models with restricted maximum-likelihood estimation were used. Heterogeneity was assessed using I2, Cochran’s Q test, τ2, and prediction intervals. Subgroup analyses by oxidative therapy type were considered exploratory. In the revised primary analysis restricted to in vitro studies, oxidative therapies reduced bacterial viability and bacterial counts compared with controls. For percentage bacterial viability reduction, nine treatment arms from three independent in vitro studies were included, and the pooled mean difference was 41.19% (95% CI: 30.45 to 51.93; p < 0.0001). For log₁₀ CFU reduction, ten treatment arms from nine independent in vitro studies were included, and the pooled mean difference was 2.53 log₁₀ CFU reduction (95% CI: 1.49 to 3.57; p < 0.0001). Heterogeneity remained very high for both outcomes (I2 = 99%), indicating that treatment effects varied according to biofilm model, microbial composition, biofilm maturity, intervention parameters, and therapy type. Antimicrobial photodynamic therapy was the most extensively studied modality and showed relatively consistent antimicrobial activity; however, subgroup comparisons were limited by unequal study distribution and residual heterogeneity. In situ, ex vivo, and clinical studies generally supported antimicrobial activity but were not pooled because of methodological and biological differences. Structural disruption of the biofilm matrix and enhanced penetration were reported in several studies, whereas complete eradication was rarely achieved. Oxidative therapies demonstrate antimicrobial activity against mature oral biofilms, particularly in experimental in vitro models. However, the magnitude of effect is variable and depends on biofilm characteristics, treatment parameters, and therapy modality. Because heterogeneity remains substantial and clinical evidence is limited, pooled estimates should be interpreted as experimental evidence rather than definitive clinical efficacy. Oxidative therapies demonstrate promising antimicrobial activity in experimental mature oral biofilm models; however, clinical effectiveness remains insufficiently established. Further well-designed clinical studies are required before firm conclusions can be drawn regarding their routine adjunctive use in clinical practice.