Efficacy and safety of probiotic therapy for halitosis: a systematic review and meta-analysis of randomized controlled trials

Objective: To evaluate the therapeutic efficacy of probiotics in managing halitosis and to determine the optimal intervention strategies. Methods: An extensive search was conducted in PubMed, Web of Science, Cochrane Library, and Embase up to December 2024, focusing on studies evaluating probiotic interventions for halitosis. Sensitivity and subgroup analyses were undertaken to assess the robustness of the results and to explore potential sources of heterogeneity. All analyses were performed through Review Manger 5.4 and STATA 15.0. Results: Of the 194 records initially identified, 10 studies met the predefined criteria. The pooled results demonstrated a significant reduction in volatile sulfur compounds (VSCs) levels in the probiotic group compared to controls (SMD = -1.01, 95% CI [-1.93, -0.09], P = 0.03). Likewise, the organoleptic test (OLT) scores showed a marked improvement in the probiotic group (RR = 1.31, 95% CI [1.22, 1.41], P < 0.00001). Nevertheless, no substantial differences were observed between groups in oral health-related quality of life (SMD = 0.21, 95% CI [-0.06, 0.49], P = 0.12), subjective oral health status (SMD = -0.04, 95% CI [-0.35, 0.28], I² = 0%, p = 0.74), depression (SMD = 0.03, 95% CI [-0.29, 0.35], I² = 0%, p = 0.85), self-esteem (SMD = -0.07, 95% CI [-0.39, 0.25], I² = 0%, p = 0.67), OLT scores (SMD = -0.24, 95% CI [-0.64, 0.16], I² = 0%, p = 0.24), or plaque index (SMD = -0.06, 95% CI [-0.57, 0.46], I² = 0%, p = 0.82). Conclusions: The findings suggest that probiotic therapy, when combined with conventional treatments, may be more effective in enhancing OLT scores and reducing VSC levels in individuals with halitosis than using probiotic alone. Nonetheless, potential publication bias, limited sample sizes, and heterogeneity among the included clinical trials may affect the reliability of these conclusions.