The effects of probiotics intervention on oral health outcomes: a comprehensive umbrella review of meta-analyses.

2026-03-26
Frontiers in oral health 7

PubMed: 41969406
DOI: 10.3389/froh.2026.1768508

Study Design

Type: Review
Population: participants from infancy to adulthood (reported mean/median ages 0.2-42.5 years)
Methods: PubMed, Web of Science and Scopus databases were searched up to October 2025 for meta-analyses of clinical trials investigating the effect of probiotics on oral health outcomes. Two reviewers screened studies, extracted data on strains, doses, durations, and pooled effect estimates, and assessed review quality using AMSTAR-2. Directions and key pooled estimates reported in included meta-analyses were summarized.

Background

Probiotics are proposed adjuncts for oral health, but findings from meta-analyses are inconsistent. We conducted an umbrella review of meta-analyses to synthesize evidence on probiotics' effects on cariogenic bacteria such as Streptococus (S.) mutans and Lactobacillus, halitosis (volatile sulfur compounds and organoleptic scores), and caries progression.

Methods

PubMed, Web of Science and Scopus databases were searched up to October 2025 for meta-analyses of clinical trials investigating the effect of probiotics on oral health outcomes. Two reviewers screened studies, extracted data on strains, doses, durations, and pooled effect estimates, and assessed review quality using AMSTAR-2. Directions and key pooled estimates reported in included meta-analyses were summarized.

Results

Eleven meta-analyses met inclusion criteria, encompassing participants from infancy to adulthood (reported mean/median ages 0.2-42.5 years), probiotic doses reported between ∼5 × 10⁵ and 5 × 10¹⁰ CFU, and intervention durations of 7 days to 24 months. Common strains included Lactobacillus, Bifidobacterium, and S. salivarius. Probiotics were associated with reductions in S. mutans counts in most reported comparisons and improved halitosis measures in the majority of comparisons. Pooled estimates for caries-related outcomes indicated modest reductions (example pooled SMDs reported∼-0.24; 95% CI -0.39 to -0.10 and for Lactobacillus rhamnosus -0.41; 95% CI -0.60 to -0.21). Most meta-analyses were rated moderate by AMSTAR-2; substantial heterogeneity, variable strains/delivery, and reliance on surrogate endpoints were common.

Conclusions

Evidence suggests modest benefits of certain probiotic strains on cariogenic bacteria and halitosis, but heterogeneity, surrogate outcomes, and moderate review quality limit certainty. High-quality, strain-specific RCTs with standardized clinical endpoints are needed.

Research Insights

Supplement	Dose	Health Outcome	Effect Type	Effect Size	Source
Lactobacillus	—	Reduced Caries Risk	Beneficial	Small	View source Pooled estimates for caries-related outcomes indicated modest reductions (example pooled SMDs reported∼-0.24; 95% CI -0.39 to -0.10 and for Lactobacillus rhamnosus -0.41; 95% CI -0.60 to -0.21).
Lactobacillus	—	Reduced Cariogenic Bacteria	Beneficial	Small	View source Probiotics were associated with reductions in S. mutans counts in most reported comparisons
Lactobacillus	—	Reduced Halitosis	Beneficial	Small	View source and improved halitosis measures in the majority of comparisons.
Lactobacillus plantarum 14D	—	Reduced Caries Risk	Beneficial	Small	View source Pooled estimates for caries-related outcomes indicated modest reductions (example pooled SMDs reported∼-0.24; 95% CI -0.39 to -0.10 and for Lactobacillus rhamnosus -0.41; 95% CI -0.60 to -0.21).
Lactobacillus plantarum 14D	—	Reduced Cariogenic Bacteria	Beneficial	Small	View source Probiotics were associated with reductions in S. mutans counts in most reported comparisons
Lactobacillus plantarum 14D	—	Reduced Halitosis	Beneficial	Small	View source and improved halitosis measures in the majority of comparisons.