Probiotics as an Adjunct Therapy for the Treatment of Halitosis, Dental Caries and Periodontitis

What are microbiological effects of the adjunctive use of probiotics in the treatment of periodontal diseases? A systematic review

Probiotics have aroused great interest as an adjunctive treatment to periodontal therapy, due to the frequent colonisation by periodontopathogens after therapy. The aim of this systematic review was to analyse in the scientific literature, evidence of the microbiological effects of probiotics as an adjunct to periodontal therapy in the treatment of periodontal diseases (PD). Only randomised controlled trials (RCT), evaluating the microbiological effect of probiotics as an adjunct to periodontal therapy. The authors conducted a search in PubMed/MEDLINE, LILACS, ScienceDirect, Web of Science and Cochrane Library to identify articles published in English until February 2020. The quality of the studies was assessed using the JADAD scale and the risk of bias was assessed according to the Cochrane Collaboration assessment tool. Of the 265 articles potentially relevant to this review, 10 studies were included. The most frequently used probiotic bacteria were those of the genus Lactobacillus spp. and the time of administration of the probiotics was between 14 days to 3 months. Most studies have shown that the adjuvant use of probiotics reduces the total mean counts of gram-negative anaerobic species (Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola and Prevotella intermedia) and gram-negative coccobacillus (Aggregatibacter actinomycetemcomitans) of subgingival plaque samples. Probiotics adjuvant to periodontal therapy reduces periodontopathogenic species in a greater proportion, compared only to periodontal therapy. Especially the Lactobacillus reuteri strain, without combination with other strains, offered a greater reduction in pathogenic bacteria associated with greater destruction of periodontal tissues and deep periodontal pockets. Researchers should perform high-quality RCT, evaluating single strains without combinations, in order to observe the microbiological benefits as adjunctive treatment of PD.

Tapioca Starch Modulates Cellular Events in Oral Probiotic Streptococcus salivarius Strains

Considering the implications of microbiota in health, scientists are in search of microbiota-oriented strategies for the effective prevention and/or treatment of a wide variety of serious diseases. A microbiota comprises diverse microorganisms with either probiotic or pathogenic properties. The fermentation of prebiotic carbohydrates by probiotic bacteria can affect host metabolism. Therefore, understanding the prebiotic-mediated metabolic modulations in probiotics is crucial to develop functional foods for the improvement of disturbed microbiota. Studies have emphasized the importance of prebiotics in probiotic therapies for mucosal diseases and highlighted the need for extensive research on oral bacteria. In the present study, the cellular events have been studied in batch cultures of probiotic Streptococcus salivarius exposed to the natural prebiotic, tapioca starch (TS). TS modulated the keystone metabolic events in Streptococcus salivarius in a dose-dependent manner. Besides increasing the live cell counts and altering the colony morphologies, TS affected the protein metabolism in terms of cellular expression and conformational changes in protein secondary structures. After treatment with TS, the nucleic acid synthesis increased and B-DNA was more than A- and Z-DNA, together with the diminished fatty acids and increased polysaccharide synthesis. The study results can be considered for the assessment of functional foods and probiotics in oral health.

Identification of Salivary Microorganisms and Metabolites Associated with Halitosis

Halitosis is mainly caused by the action of oral microbes. The purpose of this study was to investigate the differences in salivary microbes and metabolites between subjects with and without halitosis. Of the 52 participants, 22 were classified into the halitosis group by the volatile sulfur compound analysis on breath samples. The 16S rRNA gene amplicon sequencing and metabolomics approaches were used to investigate the difference in microbes and metabolites in saliva of the control and halitosis groups. The profiles of microbiota and metabolites were relatively different between the halitosis and control groups. The relative abundances of Prevotella, Alloprevotella, and Megasphaera were significantly higher in the halitosis group. In contrast, the relative abundances of Streptococcus, Rothia, and Haemophilus were considerably higher in the control group. The levels of 5-aminovaleric acid and n-acetylornithine were significantly higher in the halitosis group. The correlation between identified metabolites and microbiota reveals that Alloprevotella and Prevotella might be related to the cadaverine and putrescine pathways that cause halitosis. This study could provide insight into the mechanisms of halitosis.

Oral colonization by Levilactobacillus brevis KABPTM-052 and Lactiplantibacillus plantarum KABPTM-051: A Randomized, Double-Blinded, Placebo-Controlled Trial (Pilot Study)

Background

To determine the oral colonization capacity of the strains Levilactobacillus brevis KABPTM-052 (CECT 7480) and Lactiplantibacillus plantarum KABPTM-051 (CECT 7481) in healthy subjects.

Material and Methods

This randomized, double-blinded, placebo-controlled study included 40 volunteers (22 females, 18 males; age range 18-55 years) with healthy gingiva or mild gingivitis, allocated to receiving probiotic chewing gum (n=20) or placebo (n=20) b.i.d for 6 weeks. At baseline and after 6 weeks of treatment, a periodontics specialist collected saliva samples to assess probiotic colonization by qPCR, and analysed dental plaque, gingival index and dental probing pocket depth in Community Periodontal Index (CPI) teeth subset. Protocol was registered as NCT03540498.

Results

Treatment compliance was high (99%). Both L. brevis and L. plantarum were detected in the oral microbiota at baseline. After 6 weeks, volunteers receiving probiotic showed a significant increase of both L. brevis (p = 0.017) and L. plantarum (p = 0.004) versus placebo. This effect remained significant after adjusting for gender and gingival index at baseline. In the probiotic group, reduction in plaque index significantly correlated to higher levels of L. brevis (rho = 0.57, p = 0.022) but not of L. plantarum at study endpoint, and the number of subjects with dental plaque was reduced during intervention (7 of 17, p = 0.016). No such effects were observed in the placebo group. No adverse drug reactions were reported.

Conclusions

Levilactobacillus brevis KABPTM-052 and Lactiplantibacillus plantarum KABPTM-051 colonize the buccal microbiota of healthy volunteers, and higher colonization by L. brevis positively correlated to reduction in dental plaque. 

Key words:Probiotic, Levilactobacillus brevis, Lactiplantibacillus plantarum, oral colonization, oral microbiota, dental plaque.

Comparative study between photodynamic therapy with urucum + Led and probiotics in halitosis reduction-protocol for a controlled clinical trial

Background

Halitosis is a term that defines any foul odor emanating from the oral cavity. The origin may be local or systemic. The aim of the proposed protocol is to determine whether treatment with antimicrobial photodynamic therapy (aPDT) and treatment with probiotics are effective at eliminating halitosis.

Materials and methods

Eighty-eight patients, from 18 to 25 years old with a diagnosis of halitosis (H₂S≥112 ppb, determined by gas chromatography) will be randomly allocated to four groups (n = 22) that will receive different treatments: Group 1 –treatment with teeth brushing, dental floss and tongue scraper; Group 2 –brushing, dental floss and aPDT; Group 3 –brushing, dental floss and probiotics; Group 4 –brushing, flossing, aPDT and probiotics. The results of the halimetry will be compared before, immediately after, seven days and thirty days after treatment. The microbiological analysis of the coated tongue will be performed at these same times. The normality of the data will be determined using the Shapiro-Wilk test. Data with normal distribution will be analyzed using analysis of variance (ANOVA). Non-parametric data will be analyzed using the Kruskal-Wallis test. The Wilcoxon test will be used to analyze the results of each treatment at the different evaluation periods.

Clinical trail registration

NCT03996044.

Oral probiotic activities and biosafety of Lactobacillus gasseri HHuMIN D

Background

Lactobacillus spp. have been researched worldwide and are used in probiotics, but due to difficulties with laboratory cultivation of and experimentation on oral microorganisms, there are few reports of Lactobacillus spp. being isolated from the oral cavity and tested against oral pathogens. This research sought to isolate and determine the safety and inhibitory capabilities of a Lactobacillus culture taken from the human body.

Results

One organism was isolated, named “L. gasseri HHuMIN D”, and evaluated for safety. A 5% dilution of L. gasseri HHuMIN D culture supernatant exhibited 88.8% inhibition against halitosis-producing anaerobic microorganisms and the organism itself exhibited powerful inhibitory effects on the growth of 11 oral bacteria. Hydrogen peroxide production reached 802 μmol/L after 12 h and gradually diminished until 24 h, it efficiently aggregated with P. catoniae and S. sanguinis, and it completely suppressed S. mutans-manufactured artificial dental plaque. L. gasseri HHuMIN D’s KB cell adhesion capacity was 4.41 cells per cell, and the cell adhesion of F. nucleatum and S. mutans diminished strongly in protection and displacement assays.

Conclusion

These results suggest that L. gasseri HHuMIN D is a safe, bioactive, lactobacterial food ingredient, starter culture, and/or probiotic microorganism for human oral health.

Review of probiotic use in otolaryngology

OBJECTIVE

Probiotics have garnered considerable attention as an intervention for various conditions common to otolaryngology. The purpose of this review is to evaluate the current literature to offer recommendations about the safety and efficacy of probiotic management in otolaryngologic conditions.

STUDY DESIGN

Narrative review.

METHODS

PubMed and Google Scholar were queried using pertinent keywords to retrieve relevant studies with particular focus in the recent 5 years. All abstracts were assessed and studies, reviews and meta-analyses achieving evaluation of probiotic therapies or characterization of microbiome changes were included for further review. Studies were categorized by condition or anatomic region across various subspecialties. Key data parameters were extracted and evaluated across studies and treatment types.

RESULTS

Strong evidence exists for the use probiotic agents to improve symptoms for allergic rhinitis, chronic rhinosinusitis and certain dental conditions. Despite promising results, further investigation is needed to evaluate and optimize probiotic delivery for mitigating otitis media, oropharyngeal inflammation and upper respiratory tract infections. Preclinical studies suggest that probiotics may potentially offer benefit for voice prosthesis maintenance, wound healing and mitigation of oral dysplasia.

CONCLUSION

Probiotic therapies may offer clinical benefit in a variety of contexts within the field of otolaryngology, especially for short-term relief of certain inflammatory conditions of the oral cavity, auditory and nasal cavities. Further investigation is warranted for evaluation of long-term outcomes and pathogenic deterrence.

Can Probiotics Emerge as Effective Therapeutic Agents in Apical Periodontitis? A Review

Apical periodontitis (AP) is a biofilm-associated disease initiated by the invasion of dental pulp by microorganisms from the oral cavity. Eradication of intracanal microbial infection is an important goal of endodontic treatment, and this is typically accomplished by mechanical instrumentation and application of sodium hypochlorite and chlorhexidine. However, these agents are tissue-irritating at higher concentrations and cytotoxic. Certain probiotics have been found effective in controlling marginal periodontitis, as evidenced by reduction of pathogenic bacterial loads, gains in clinical attachment levels, and reduced bleeding on probing. In vitro studies have shown inhibitory activity of some probiotics against endodontic pathogens. Similarly, in vivo studies in rats have demonstrated a positive immuno-modulatory role of probiotics in AP, as manifested by decreased levels of proinflammatory markers and increased levels of anti-inflammatory markers. A role for probiotics in effecting a reduction of bone resorption has also been reported. This review provides an outline of current research into the probiotic management of AP, with a focus on understanding the mechanisms of their direct antagonistic activity against target pathogens and of their beneficial modulation of the immune system.

Effects of adjunctive light-activated disinfection and probiotics on clinical and microbiological parameters in periodontal treatment: a randomized, controlled, clinical pilot study

Objectives

The aim of this pilot study was to evaluate the clinical and microbiological outcomes of light-activated disinfection (LAD) alone or combined with probiotics as an adjunct to non-surgical periodontal treatment.

Materials and methods

In this single-blinded, randomized, controlled clinical pilot study, 48 patients (28 females and 20 males) with untreated periodontitis (stages II and III, grade B) were included. Using a parallel-group design, patients were randomly assigned into 3 groups to receive subgingival debridement (SD) alone (group 1, n = 16), SD with LAD (group 2, n = 16), or SD with LAD plus probiotic treatment (group 3, n = 16). Probing pocket depth (PPD), clinical attachment level (CAL), bleeding on probing (BOP), gingiva-index simplified (GIs), plaque-control record (PCR), and subgingival microbiological samples were analyzed at baseline, 3 months, and 6 months of follow-up.

Results

All treatment modalities demonstrated clinical improvements in PPD and CAL at 6 months compared to baseline but without a statistical significant difference between the groups. The combination of SD + LAD + probiotic treatment (group 3) demonstrated significantly greater reductions in BOP, GIs, and red complex bacteria P. gingivalis and T. forsythia compared with other groups at 6 months (p < 0.05).

Conclusions

A single application of LAD as an adjunct to SD provided no additional clinical and microbiological benefits compared to SD alone. The combination of SD + LAD + probiotic treatment in group 3 led to further improvements of the inflammatory parameters.

Clinical relevance

The additional use of probiotics in periodontal treatment can be a useful approach to support inflammation and infection control of periodontal tissues. Further studies are necessary to determine the extent of added benefit for this treatment approach.

Evaluation of the Effect of Probiotic Bacillus coagulans Unique IS2 on Mutans Streptococci and Lactobacilli Levels in Saliva and Plaque: A Double-Blind, Randomized, Placebo-Controlled Study in Children

Background

Probiotic organisms are known to reduce caries causing microorganisms mutans streptococci and lactobacilli. Aim of the Study. To evaluate the effect of probiotic Bacillus coagulans Unique IS2 on mutans streptococci and lactobacilli levels in saliva and plaque in children.

Introduction

Dental caries or tooth decay is because of the demineralization of the tooth enamel leading to the breakdown of the enamel causing cavities to be formed. Demineralization of the tooth happens because of the acid secreted by bacteria like mutans streptococci and lactobacilli. It is now suggested that probiotic usage prevents the overgrowth of these pathogenic microbes, thereby reducing caries activity. Methodology. In this double-blind, randomized, placebo-controlled study, 48 children with ages ranging from 5 to 15 years were divided into two groups, the probiotic and placebo groups. Chewable tablets with and without probiotic Bacillus coagulans Unique IS2 were administered for two weeks. Stimulated saliva samples and plaque were collected at baseline and at the end of 14 days to measure the pH, mutans streptococci, and lactobacilli count of saliva and plaque using chairside kits.

Results

A statistically significant reduction in mutans streptococci and lactobacilli counts of both saliva and plaque samples was observed in the B. coagulans Unique IS2 treated group after 14 days of administration compared to the baseline and placebo group (using paired t-test).

Conclusion

Probiotic Bacillus coagulans Unique IS2 (2 billion cfu) chewable tablet is effective in reduction and inhibition of caries causing mutans streptococci and lactobacilli levels in saliva and plaque in children.

An Assessment of the Stability of the Canine Oral Microbiota After Probiotic Administration in Healthy Dogs Over Time

The administration of an oral probiotic has been demonstrated to impact oral microbial diversity in humans but has not been examined in canines. The objective of this study was to test the hypothesis that oral probiotic administration would impact the oral microbiota of canines compared to control. Working canines in training (n = 13) were assigned to Test or Control groups and acclimated to one of three commercially available study diets utilizing common protein sources (Purina Pro Plan Savor lamb, Purina Pro Plan Sport chicken, Purina Pro Plan Focus salmon) for a minimum of 30 days prior to initiation of the study. Following acclimation, dogs in the Test group began a daily regimen of oral probiotic (Fortiflora® Purina, St. Louis, MO) top-dressed on their midday feeding. Control dogs received their midday feeding with no probiotic. All dogs were sampled once weekly via oral pediatric swabs across the 7-week study. Next generation sequencing (Illumina, MiSeq) was utilized to develop microbial profiles specific to treatment, diet, and time. Bacterial composition was dominated by eight phyla (Proteobacteria 43.8%, Bacteroidetes 22.5%, Firmicutes 18.9%, Actinobacteria 6.1%, Fusobacteria 3.6%, Gracilibacteria 2.1%, SR1 Absconditabacteria 1.5%, and Saccharibacteria 1.3%) representing more than 99% of the relative abundance of the microbial composition. Probiotic administration failed to impact relative abundance at any taxonomic level (P > 0.05). Similarly, no effect on the oral microbiota was measured for diet (P > 0.05). Comparison using a Jaccard Index demonstrate a consistent microbial profile over the 7-week study with no impact evidenced by study week (P = 0.19). The data also revealed a profile of ubiquitous taxa that were present across all dogs and all samples regardless of breed, sex, diet, treatment or other factors. These genera include Actinomyces, Corynebacterium, Capnocytophaga, Flavobacterium, Gemella, Abiotrophia, Streptococcus, and Frederiksenia. These data demonstrate the stability of canine oral microbiota over time.

Probiotic Effects on Multispecies Biofilm Composition, Architecture, and Caries Activity In Vitro

While probiotics have been tested for their anti-caries effect in vitro and also clinically, there is a lack of understanding of their effects on complex dental biofilms. We assessed two probiotics, Lactobacillus reuteri and Streptococcus oligofermentans, on a continuous-cultured model containing Streptococcus mutans, Lactobacillus rhamnosus and Actinomyces naeslundii. Cariogenic biofilms were grown on bovine enamel specimens and daily challenged with L. reuteri or S. oligofermentans whole culture (LC/SC) or cell-free supernatant (LS/SS) or medium only (negative control, NC) (n = 21/group) for 10 days. Biofilm was assessed via counting colony-forming units, quantitative polymerase chain reaction, and fluorescence in situ hybridization. Caries activity was determined by pH measurements and by assessing mineral loss (ΔZ) using transverse microradiography. Both LC and SC significantly reduced total and strain-specific cariogenic bacterial numbers (p < 0.05). ΔZ was reduced in LC (mean ± SD: 1846.67 ± 317.89) and SC (3315.87 ± 617.30) compared to NC (4681.48 ± 495.18, p < 0.05). No significant reductions in bacterial numbers and ΔZ was induced by supernatants. Biofilm architecture was not considerably affected by probiotic applications. Viable probiotics L. reuteri and S. oligofermentans, but not their culture supernatants, could reduce the caries activity of multi-species biofilms in vitro.

The Underestimated Problem of Intra-Oral Halitosis in Dental Practice: An Expert Consensus Review

Approximately 90% of halitosis cases originate within the oral cavity (intra-oral halitosis). With a focus on intra-oral halitosis, this narrative review article provides a current summary of the epidemiology, diagnosis and management of halitosis and discusses practical considerations for healthcare professionals (HCPs), including dentists, dental hygienists, general practitioners, community pharmacists, nurses and medical specialists. MEDLINE and PubMed were searched up to 31 December 2019. Additional information was sourced from reference lists of relevant published literature. Full-text articles which reported on the epidemiology, diagnosis and management of halitosis were considered for inclusion. Halitosis affects substantial numbers of individuals globally and is an underestimated problem in dental practice. Current estimates of the prevalence of halitosis, in addition to diagnostic methods and management considerations for halitosis, are discussed. Although not a life-threatening condition, halitosis has a significant impact on patients’ quality of life and can result in psychological consequences including social, professional and affective limitations. Using a simple step-wise approach for diagnosis and treatment, dentists and dental hygienists are ideally placed to respond to an initial consultation for halitosis.

Effectiveness of Probiotic Lozenges in Periodontal Management of Chronic Periodontitis Patients: Clinical and Immunological Study

OBJECTIVE

 The main purpose of this article was to evaluate the effect of probiotics used as an adjunctive to scaling and root planing (SRP) on the periodontal parameters and matrix metalloproteinase-8 (MMP-8) levels in gingival crevicular fluid (GCF) of chronic periodontitis patients.

MATERIALS AND METHODS

 A total of 25 chronic periodontitis patients who completed the treatment course of 40 subjects, aged 25 to 58 years, participated in this study. They were categorized into two groups: the first group was treated by SRP while the second group was treated by SRP and probiotic lozenges twice a day for 30 days. All patients were evaluated clinically by measuring the plaque index, bleeding index (BI), pocket depth, clinical attachment loss, and immunologically by assaying GCF/MMP-8 at baseline and 30 days after periodontal management.

RESULTS

 There was a significant improvement in periodontal parameters after SRP treatment with and without probiotic lozenges in both groups. However, there was a significant decrease in the BI (p = 0.05) in SRP and probiotic lozenges group after 30 days compared with SRP alone. In addition, there was a significant decrease in GCF/MMP-8 levels after 30 days in patients managed by SRP only (p = 0.017) compared with the baseline in both groups, whereas a highly significant decrease in patients treated by SRP and probiotics (p = 0.001).

CONCLUSION

 The current study suggested that the probiotics might have a beneficial effect on clinical and immunological outcomes in the management of chronic periodontitis patients. Further research is needed on a large-scale population and for a long recall time to confirm the response to probiotics as an adjunctive to SRP.

LncRNA TUG1 mediates lipopolysaccharide-induced proliferative inhibition and apoptosis of human periodontal ligament cells by sponging miR-132

Emerging evidence shows that the long noncoding RNA taurine-upregulated gene 1 (TUG1) plays pivotal roles in regulating biological properties and functions of parenchyma cells in various types of disease processes. However, the mechanism underlying the effects of TUG1 on cell proliferation and apoptosis of human periodontal ligament cells (PDLCs) in periodontitis is undefined. In this study, we explored the functions of TUG1 and its underlying mechanisms in the inflammatory process induced by Porphyromonas gingivalis-derived lipopolysaccharide (LPS) in PDLCs. Our results showed that TUG1 had a decreased expression in both periodontal ligament (PDL) tissues with periodontitis and PDLCs under a LPS-induced inflammatory condition, and TUG1 expression was negatively correlated with miR-132 expression in periodontitis-affected PDL tissues. Furthermore, we found that TUG1 overexpression in PDLCs alleviated LPS-induced proliferative inhibition and apoptosis promotion, while TUG1 knockdown had the opposite effect. In addition, miR-132 inhibitor alleviated TUG1 knockdown-induced inhibition of proliferation and increase of apoptosis in PDLCs under inflammatory conditions induced by LPS. These findings indicated that TUG1 has an enormous potential in regulating cell proliferation and apoptosis of PDLCs during periodontitis and may provide an effective therapeutic target for periodontitis to reduce the damage caused by inflammatory reactions.

circRNA CDR1as Regulated the Proliferation of Human Periodontal Ligament Stem Cells under a Lipopolysaccharide-Induced Inflammatory Condition

circRNA CDR1as (CDR1as) has been demonstrated to play important roles in a variety of inflammation-related diseases by acting as miRNA sponges. The present study is aimed at investigating the potential roles of CDR1as in the proliferation of human periodontal ligament stem cells (PDLSCs) under an inflammatory condition induced by Porphyromonas gingivalis-derived lipopolysaccharide (LPS). Human periodontal ligament cells (PDLCs) were isolated from periodontal ligament tissue, and PDLSCs were sorted from PDLCs based on the STRO-1 expression through fluorescence-activated cell sorting. We further found that CDR1as was significantly downregulated in LPS-treated PDLSCs compared to untreated cells, as well as in normal periodontal ligament tissues compared to periodontitis tissues. Knockdown of CDR1as promoted LPS-induced proliferative inhibition of PDLSCs, whereas overexpression of CDR1as alleviated the LPS-induced proliferative ability of PDLSCs. Mechanistically, CDR1as functioned as an miR-7 sponge to activate the ERK signal pathway to mediate the inhibition effect of LPS on cell proliferation. Taken together, our findings revealed the effects of the interacting pair of CDR1as/miR-7 on the proliferation ability of PDLSCs within their surrounding inflammatory microenvironment of periodontitis.

Oral probiotics reduce halitosis in patients wearing orthodontic braces: a randomized, triple-blind, placebo-controlled trial

Orthodontic braces can impede oral hygiene and promote halitosis. The aim of the study was to investigate the effect of the oral probiotic Streptococcus salivarius M18 on oral hygiene indices and halitosis in patients wearing orthodontic braces. The study was a prospective, randomized, triple-blind, placebo-controlled trial. Patients undergoing fixed orthodontic treatment were randomly allocated to a probiotic group (n = 32) and a placebo group (n = 32). Patients consumed 2 lozenges d^-1 for one month. Assessments were taken at baseline, at the end of the intervention, and at a 3 month follow-up. The outcome measures were plaque index (PI), gingival index (GI) and halitosis-causing volatile sulfur compound (VSC) levels. The dental biofilms before and after the intervention were analyzed utilizing next-generation sequencing of bacterial 16S rRNA genes. PI and GI scores were not significantly influenced by the probiotic intervention (intervention × time: p > 0.05). The level of VSCs decreased significantly in both the probiotic group (VSC reduction = -8.5%, 95%CI = -7.4% to -9.1%, p = 0.015) and the placebo group (-6.5%, 95%CI = -6.0% to -7.4%, p = 0.039) after 1 month intervention. However, at the 3 month follow-up, the VSC levels in the placebo group returned to baseline levels whereas those in the probiotic group decreased further (-10.8%, 95%CI = -10.5% to -12.9%, p = 0.005). Time, but not treatment, was associated with the decrease in microbial community alpha diversity and a modest effect on beta diversity. Oral probiotic S. salivarius M18 reduced the level of halitosis in patients with orthodontic braces, but had minimal effects on PI, GI and dental biofilm microflora.