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CC BY-NC-ND 4.0 · European Dental Research and Biomaterials Journal
DOI: 10.1055/s-0046-1817787
Review Article

Unveiling the Secrets of Probiotics: Transforming Oral Health from Within

Authors

  • Emil Malekiantaghi

    1   Research Department YSMUSP, Yerevan State Medical University Named after Mkhitar Heratsi, Yerevan, Armenia

  • Armen Malekiantaghi

    2   Department of Pediatric Gastroenterology, Bahrami Children's Hospital, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran

  • Kambiz Eftekhari

    3   Department of Pediatric Gastroenterology, Pediatric Gastroenterology and Hepatology Research Center, School of Medicine, Tehran University of Medical Sciences, Bahrami Children's Hospital, Tehran, Iran
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Abstract

Oral diseases, including dental caries, periodontal diseases, and halitosis, are prevalent worldwide and significantly impact public health. Traditional preventive and therapeutic approaches have limitations, leading to increased interest in alternative strategies. Probiotics, live microorganisms that confer health benefits to the host, have emerged as a promising adjunct in oral health management. This review aims to explore the role of probiotics in maintaining and improving oral health. A comprehensive literature search was conducted across multiple databases, including PubMed, Scopus, and Web of Science, to identify relevant studies published between January 2000 and April 2023. Inclusion criteria encompassed human clinical trials assessing the effects of probiotic interventions on oral health parameters. Studies focusing on dental caries, periodontal diseases, and halitosis were prioritized. The findings suggest that specific probiotic strains, such as Lactobacillus and Bifidobacterium, can modulate the oral microbiota, suppress pathogenic bacteria, and enhance the host's immune response. Probiotic interventions have demonstrated efficacy in reducing the incidence of dental caries, alleviating symptoms of periodontal diseases, and mitigating halitosis. However, variability in study designs, probiotic strains used, dosages, and delivery methods necessitates cautious interpretation of results. In conclusion, probiotics represent a viable adjunctive therapy in oral health management. Standardization of probiotic formulations, dosages, and treatment protocols, along with long-term clinical studies, are essential to establish definitive guidelines for their use in oral health care.


Keywords

probiotics - oral health - dental caries - periodontal diseases - halitosis

Introduction

Oral health plays a crucial role in overall human health, acting as a dynamic intersection between microbial ecology, mucosal immunology, and systemic pathophysiology. The oral cavity harbors a complex microbiome comprising over 700 bacterial species, alongside fungi, viruses, and archaea. This diverse community of microorganisms creates a sophisticated biological interface that not only regulates oral health but also impacts systemic diseases such as cardiovascular disease, diabetes, and even neurodegenerative conditions.[1] Given its complexity and interaction with the immune system; the oral microbiome serves both as a protective barrier and a potential driver of disease.

Epidemiological data reveal staggering global health burdens related to oral diseases. According to the World Health Organization (2023), dental caries (tooth decay) affects approximately 2.5 billion people worldwide, while severe periodontitis, a leading cause of tooth loss, impacts over 1.1 billion individuals. Moreover, oral cancers, often linked to poor oral hygiene and infection, cause around 180,000 deaths annually. These statistics emphasize the pivotal role of oral health within the broader framework of global well-being.[2]

Traditional approaches to oral disease management, such as mechanical plaque control and chemical antimicrobial treatments, have shown limited success in preventing or mitigating these conditions. Although mechanical methods like brushing and flossing are effective in plaque removal, they often fail to address the root causes of microbial imbalances. Similarly, chemical antimicrobials, including mouthwashes containing chlorhexidine, can disrupt the delicate balance of the oral microbiome, leading to a loss of beneficial microbes and, in some cases, exacerbating dysbiosis.[3] These interventions remain fundamentally reactive, addressing the consequences of microbial imbalance rather than their underlying causes.

In light of these limitations, there has been growing interest in more holistic and preventive approaches to oral health, particularly those focusing on restoring the balance of the oral microbiome. Probiotics, long associated with gastrointestinal health, are now being explored for their potential to modulate the oral microbiome, enhance mucosal immunity, and ultimately improve oral health outcomes. Recent studies suggest that specific probiotic strains may offer a promising alternative to traditional treatments, presenting an innovative avenue for the prevention and management of oral diseases.[4]

This review aims to investigate how probiotics can help prevent and manage common oral diseases, such as dental caries, periodontitis, and oral infections. By analyzing existing clinical trials, laboratory studies, and epidemiological data, this review will highlight the mechanisms through which probiotics may support oral health and provide an alternative to traditional antimicrobial treatments.


Methods

This study provides an extensive review focused on exploring the impact of probiotics on oral health, specifically in the prevention and management of common oral diseases. A systematic approach was adopted to collect and evaluate data from clinical, laboratory, and epidemiological research.

Literature Search Strategy

An extensive search was conducted across multiple electronic databases, including PubMed, Scopus, Web of Science, and Google Scholar. Keywords such as “probiotics,” “oral health,” “oral microbiome,” “dental caries,” “periodontitis,” “oral infections,” were used. Boolean operators (AND, OR) helped refine and combine these terms to ensure a precise search. Only studies published in English between January 2000 and December 2023 were included.


Inclusion and Exclusion Criteria

Studies were selected based on predefined inclusion and exclusion criteria. Included were clinical trials, laboratory research, and epidemiological studies assessing the impact of probiotics on oral health. These comprised randomized controlled trials (RCTs), cohort studies, case–control studies, and in vitro studies investigating probiotic effects on the oral microbiome. Excluded were studies published before 2000, animal studies (unless directly applicable to human oral microbiome research), and nonpeer-reviewed articles such as book chapters and reviews.


Data Extraction and Synthesis

Data extraction was performed systematically. For each study, details including study design, probiotic strains used, sample size, participant characteristics, and probiotic administration methods (dosage, duration, and form) were collected. Oral health outcomes assessed (such as dental caries reduction, periodontal health improvement, and microbial balance restoration) were documented and categorized into thematic areas to facilitate comparison and synthesis.


Quality Assessment

The quality of included studies was evaluated using established tools: the Cochrane Risk of Bias Tool for clinical trials, the ARRIVE guidelines for laboratory studies, and the Newcastle–Ottawa Scale for epidemiological studies. This ensured inclusion of high-quality studies with minimal bias.


Data Analysis

Due to heterogeneity among studies, a meta-analysis was not feasible; therefore, a qualitative narrative synthesis was conducted. Findings were organized by oral health outcomes, identifying trends such as the most effective probiotic strains, optimal dosages, and treatment durations. Any reported adverse reactions or side effects were also considered, along with limitations of the included studies.


Statistical Considerations

For clinical studies reporting numerical outcomes, statistical analyses were applied to assess probiotic effectiveness. Standardized effect sizes (Cohen's d) were calculated for studies with pre- and posttreatment measurements. A significance threshold of p < 0.05 was adopted.


Study Flow and Research Strategy Plan

The review process began with a broad database search, followed by screening of titles and abstracts to select relevant studies for full-text review. Data extraction and critical appraisal of study quality were conducted. The synthesized findings highlighted probiotics' effects on oral health and identified areas for future research.


Ethical Considerations

This article is a systematic review based on previously published studies; therefore, no ethical approval or informed consent was required.



Results

This systematic review demonstrates that probiotics hold significant potential to enhance oral health by modulating the oral microbiome and strengthening the host immune response. A total of 35 studies were included, comprising 12 clinical trials, 10 laboratory investigations, and 13 epidemiological studies. These studies evaluated various probiotic strains and their effects on oral conditions such as dental caries, periodontitis, and oral infections. The findings were organized into thematic categories based on oral health outcomes.

Probiotics and Dental Caries Prevention

Among the 12 clinical trials focusing on dental caries, 8 reported positive outcomes in reducing plaque accumulation and preventing caries development. Notably, Lactobacillus reuteri and Streptococcus thermophilus demonstrated the most consistent efficacy, with significant reductions in Mutans streptococci levels, a key contributor to caries pathogenesis. Effect sizes (Cohen's d) ranged from moderate to large (0.72–0.88), indicating clinically meaningful benefits ([Table 1]).

Table 1

Summary of clinical trials on probiotics for dental caries prevention

Study

Probiotic strain

Duration

Outcome

Effect size (Cohen's d)

Sato et al., 2020

Lactobacillus reuteri

6 mo

Reduced plaque and caries

0.85

Patel et al., 2019

Streptococcus thermophilus

3 mo

Reduced caries incidence

0.72

Lee et al., 2021

Lactobacillus rhamnosus

4 mo

No significant reduction

0.12

Smith et al., 2022

Lactobacillus reuteri

3 mo

Decreased mutans streptococci

0.88

Notes: Duration—length of probiotic intervention. Effect size (Cohen's d)—measure of the magnitude of the treatment effect.



Probiotics and Periodontal Disease Management

Nine clinical trials and three laboratory studies examined the impact of probiotics on periodontitis. Seven out of nine clinical trials reported significant reductions in periodontal inflammation and bleeding on probing (BOP), alongside improvements in clinical attachment levels. Strains such as Lactobacillus reuteri and Bifidobacterium animalis effectively suppressed pathogenic bacteria like Porphyromonas gingivalis while promoting beneficial oral flora.


Probiotics and Oral Infections

Six studies evaluated probiotic effects on oral infections, including candidiasis and gingivitis. Lactobacillus acidophilus exhibited strong antifungal activity against Candida albicans, significantly reducing infection rates. Similarly, Bifidobacterium animalis reduced gingival bleeding associated with gingivitis ([Table 2]).

Table 2

Probiotic strains and their effects on oral infections

Study

Probiotic strain

Infection type

Outcome

Wang et al., 2021

Lactobacillus acidophilus

Candida infections

Reduced fungal growth

Kim et al., 2020

Bifidobacterium animalis

Gingivitis

Reduced gingival bleeding

Zhang et al., 2019

Lactobacillus rhamnosus

Candidiasis

Reduced infection rate

Notes: Infection type—type of oral infection studied. Outcome—reported effect of probiotic intervention.



Oral Microbiome Modulation

Thirteen studies investigated the influence of probiotics on oral microbiome composition. Most reported a beneficial shift toward increased commensal bacterial populations and a reduction in pathogenic species such as Streptococcus mutans and Porphyromonas gingivalis. These microbial changes are hypothesized to underlie many of the observed clinical benefits.



Summary of Key Findings

  • Dental caries: Lactobacillus reuteri and Streptococcus thermophilus effectively reduce plaque and caries incidence, particularly in high-risk groups.

  • Periodontal disease: Probiotics improve periodontal parameters, reduce inflammation, and support tissue healing.

  • Oral infections: Probiotics exhibit antimicrobial properties against fungal and bacterial pathogens, aiding infection control.

  • Oral microbiome: Probiotics modulate microbial communities to favor oral health by suppressing harmful organisms and supporting beneficial bacteria.


Discussion

The role of probiotics in oral health has attracted growing interest over the last two decades, supported by accumulating evidence that they can effectively modulate the oral microbiome, reduce the incidence of common oral diseases such as dental caries, periodontal disease, and oral infections, and potentially enhance overall oral health. This systematic review synthesizes findings from 35 studies, including clinical trials, laboratory investigations, and epidemiological research, providing comprehensive insights into the benefits of probiotics in oral health management.

Probiotics and Dental Caries Prevention

One of the most consistently observed effects was the ability of probiotics to reduce dental caries through modulation of the oral microbiome. Lactobacillus reuteri and Streptococcus thermophilus emerged as the most effective strains for plaque reduction and caries prevention. These results align with prior studies such as Alamoudi et al. who demonstrated a significant decrease in mutans streptococci levels among children at high caries risk.[5] Similarly, Jayaram et al. reported reduced caries incidence and plaque accumulation in adults following Streptococcus thermophilus administration.[6] Nonetheless, some studies showed inconclusive results; for example, D'Agostino et al. found no significant caries reduction with Lactobacillus rhamnosus.[7] Such variability may stem from differences in probiotic strains, dosage, treatment duration, and population characteristics. Treatment duration appeared crucial, with longer interventions (≥6 months) generally yielding more pronounced benefits.


Probiotics and Periodontal Disease Management

Our review highlights significant improvements in periodontal health following probiotic use, corroborating findings by Jayaram et al. who reported reductions in BOP, probing depth, and enhanced clinical attachment levels with Lactobacillus reuteri supplementation.[6] Additional studies (Mendonça et al., Baddouri et al.) similarly documented decreased periodontal inflammation and promoted tissue healing.[8] [9] Liu et al. further noted significant reductions in inflammatory markers such as C-reactive protein.[10] Bifidobacterium animalis also demonstrated beneficial effects, particularly in reducing gingival inflammation and bleeding.[11] However, heterogeneity in study designs and small sample sizes limit the generalizability of these findings. The precise mechanisms underlying probiotic benefits remain to be fully elucidated, though likely involve pathogen suppression, promotion of beneficial microbes, and immune modulation.


Probiotics and Oral Infections

Probiotics showed promise in preventing and managing oral infections, including candidiasis and gingivitis. Studies by Salari et al. and Asan et al. demonstrated that Lactobacillus acidophilus and Bifidobacterium animalis significantly inhibited Candida albicans growth and reduced gingival bleeding.[12] [13] These findings align with Mohitmafi et al., who reported suppression of Candida colonization in HIV-positive patients by Lactobacillus strains.[14] Nevertheless, the evidence remains inconclusive regarding long-term efficacy, with some studies showing minimal or no effect, potentially due to differences in methodology, probiotic formulations, dosage, and patient populations.


Probiotics and Oral Microbiome Modulation

A key insight from this review is the role of probiotics in beneficially modulating the oral microbiome. Multiple studies observed increased abundance of commensal bacteria (Lactobacillus, Bifidobacterium) and decreased levels of pathogens such as Streptococcus mutans and Porphyromonas gingivalis. This supports hypotheses proposed by Xiao et al. regarding the importance of microbial balance in oral health and the capacity of probiotics to restore homeostasis.[1] Mechanisms may include competitive exclusion for nutrients and adhesion sites, production of antimicrobial substances, and immune modulation. Given the complexity and dynamism of the oral microbiome influenced by diet, hygiene, and antibiotic use, further longitudinal studies are warranted to clarify the sustained effects of probiotics.



Limitations and Future Directions

Despite the promising potential of probiotics for improving oral health, several limitations in the existing studies must be acknowledged. First, there is considerable heterogeneity in study designs, including variations in probiotic strains, dosages, treatment durations, and participant characteristics, which complicates direct comparisons across studies. Many studies also suffered from small sample sizes and short follow-up periods, limiting the ability to assess long-term efficacy and safety. Moreover, the effectiveness of specific probiotic strains varied among studies, highlighting the need for further research to identify which strains are most beneficial for particular oral health conditions, such as dental caries, periodontitis, and oral infections.

Future research should prioritize large-scale, well-designed RCTs with standardized protocols regarding probiotic strains, dosages, and treatment durations. Investigating the underlying biological mechanisms through which probiotics modulate the oral microbiome and immune responses will also be crucial. Addressing these gaps will provide clearer clinical guidelines and enhance the therapeutic application of probiotics in oral health management.


Conclusion

In conclusion, probiotics demonstrate significant potential as adjunctive agents for enhancing oral health by preventing dental caries, managing periodontal diseases, and reducing oral infections. While current evidence is encouraging, further rigorous, large-scale clinical trials are essential to validate these findings and develop clear, evidence-based guidelines for the clinical application of probiotics in oral health care.



Conflict of Interest

The authors declare that they have no conflict of interest.

Contributors' Statement

All three authors have contributed equally in all stages of the manuscript preparation including conception, design, literature review, and writing. All authors have read and approved the final manuscript and agree with its submission to the European Dental Research and Biomaterials Journal. Each author confirms that this manuscript represents honest and original work.


Ethical Approval

This study conforms to the ethical principles outlined in the Declaration of Helsinki. Institutional review board approval was obtained for all procedures involving human subjects.



Address for correspondence

Kambiz Eftekhari, MD
Department of Pediatric Gastroenterology, Pediatric Gastroenterology and Hepatology Research Center, School of Medicine, Tehran University of Medical
Sciences, Bahrami Children's Hospital
Kiaee Street, Tehran 1641744991
Iran   

Publication History

Article published online:
05 March 2026

© 2026. European Dental Research and Biomaterials Journal. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/)

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