The oral microbiome - an update for oral healthcare professionals. Br Dent J. 2016;221:657-666. [PMID: 27857087 DOI: 10.1038/sj.bdj.2016.865]

Phellodendron bark extract and berberine chloride suppress microbiome dysbiosis in a saliva-derived in vitro microcosm biofilm model

OBJECTIVE

Preventing oral microbiome dysbiosis is crucial for averting the onset and progression of periodontal diseases. Phellodendron bark extract (PBE) and its active component berberine exhibit antibacterial properties against periodontal pathogenic bacteria. Although they inhibit Porphyromonas gingivalis (P. gingivalis)-induced dysbiosis in vitro in multiple species of saliva-derived planktonic cultures, their effects on microcosm biofilm models remain unclear. In this study, we aimed to elucidate the dysbiosis-suppressive effects of PBE and berberine chloride (BC) on biofilm formation.

DESIGN

PBE or BC was added during the formation of in vitro microcosm biofilms containing saliva and P. gingivalis, which were anaerobically cultured for one week. Next-generation sequencing was performed to assess microbiota composition, while quantitative real-time PCR was used to measure bacterial concentrations. Additionally, the butyrate concentration in the culture supernatant was assessed as biofilm pathogenicity.

RESULTS

PBE and BC treatments reduced the relative abundance of periodontal pathogenic bacteria, including P. gingivalis, and significantly increased the relative abundance of the genus Streptococcus and nitrate-reducing bacteria, including the genera of Neisseria and Haemophilus. Moreover, the treatment groups exhibited significantly decreased butyrate concentrations.

CONCLUSIONS

Our findings suggest that PBE and BC could suppress dysbiosis triggered by P. gingivalis in microcosm biofilms in vitro by decreasing the relative abundance and amount of periodontal pathogenic bacteria and enhancing those of nitrate-reducing bacteria that have a high relative abundance in orally healthy individuals. In summary, PBE and BC may contribute to the prevention of periodontal disease through their dysbiosis-suppressive and anti-inflammatory effects.

SloR-SRE binding to the S. mutans mntH promoter is cooperative

Streptococcus mutans is a commensal member of the plaque microbiome. It is especially prevalent when dietary sugars are available for S. mutans fermentation, generating acid byproducts that lower plaque pH and foster tooth decay. S. mutans can survive in the transient conditions of the mouth, in part because it can regulate the uptake of manganese and iron during periods of feast when metal ions are available, and famine when they are limited. S. mutans depends on a 25kDa metalloregulatory protein, called SloR, to modulate the uptake of these cations across the bacterial cell surface. When bound to manganese, SloR binds to palindromic recognition elements in the promoter of the sloABC genes that encode the major manganese transporter in S. mutans. Reports in the literature describe MntH, an ancillary manganese transporter in S. mutans, that is also subject to SloR control. In the present study, we performed expression profiling experiments that reveal coordinate regulation of the sloABC and mntH genes at the level of transcription. In addition, we describe a role for the mntH gene product that is redundant with that of the sloABC-encoded metal ion uptake machinery. The results of DNA-binding studies support direct SloR binding to the mntH promoter region which, like that at the sloABC promoter, harbors three palindromic recognition elements to which SloR binds cooperatively to repress downstream transcription. These findings expand our understanding of the SloR metalloregulome and elucidate SloR-DNA binding that is essential for S. mutans metal ion homeostasis and fitness in the oral cavity.

IMPORTANCE

Dental caries disproportionately impacts low-income socioeconomic groups in the United States and abroad. Research that is focused on S. mutans, the primary causative agent of dental caries in humans, is significant to mitigation efforts aimed at alleviating or preventing dental caries. The SloR protein is a major regulator of the S. mutans metal ion uptake machinery encoded by the sloABC- and mntH genes. This SloR-mediated gene control is essential for maintaining intracellular metal ion homeostasis, and hence S. mutans fitness in the plaque microbiome. An improved understanding of the sloABC and mntH metal ion transporters and their regulation by SloR can guide rational drug design that, by targeting the SloR-DNA-binding interface, can alleviate or prevent S. mutans-induced disease.

Balancing the Oral Redox State: Endogenous and Exogenous Sources of Reactive Oxygen Species and the Antioxidant Role of Lamiaceae and Asteraceae

Background/Objectives: Oral health is a complex concept involving physical, psychological, emotional, and social components. A key factor in maintaining oral tissue integrity is redox balance, which is disrupted by oxidative stress (OS) through an imbalance between reactive oxygen species (ROS) and antioxidant defenses. This study examines the contribution of endogenous and exogenous sources to OS and explores the therapeutic potential of medicinal plants from the Asteraceae and Lamiaceae families in restoring redox homeostasis and improving oral health. Methods: A literature review was conducted, analyzing the role of OS in oral diseases and the antioxidant mechanisms of selected Asteraceae species. Special attention was given to their phytochemical contents-polyphenols, flavonoids, and essential oils-and their biological relevance to oral health. Results: OS plays a critical role in the onset and progression of oral conditions such as caries, periodontitis, gingivitis, aphthous ulcers, abscesses, precancerous lesions, and oral cancers. ROS and reactive nitrogen species (RNS) cause inflammation, tissue breakdown, and salivary gland dysfunction. Asteraceae plants like Matricaria chamomilla, Calendula officinalis, Cichorium intybus, Taraxacum officinale, Arctium lappa, Achillea millefolium, and Solidago virgaurea demonstrate notable antioxidant, anti-inflammatory, and antimicrobial properties that help counteract OS and support oral homeostasis. Conclusions: Asteraceae and Lamiaceae species show high therapeutic potential in addressing OS-related oral disorders. Their bioactive compounds aid in restoring redox balance and protecting oral tissues. These findings support the integration of phytotherapeutic agents into oral healthcare and call for further clinical validation of plant-based strategies for disease prevention and management.

Exploring the Effect of Enzyme and Protein-Containing Toothpaste on Gum Health: A Systematic Review

This systematic review critically evaluates the efficacy of enzyme- and protein-containing toothpastes in augmenting saliva's inherent protective mechanisms. Adhering to PRISMA guidelines and having been registered under PROSPERO (CRD42024558854), a comprehensive literature search was conducted across PubMed, Web of Science, and Scopus, employing a PICO-structured query with the MeSH terms "enzymes", "proteins", and "toothpaste". The inclusion criteria were restricted to in vivo human studies, published in English within the last 10 years, assessing the gingival effects of these toothpastes. Risk of bias was assessed using the Cochrane RoB 2.0 for randomized controlled trials (RCTs) and ROBINS-I for non-randomized controlled trials (N-RCTs). From an initial pool of 62 articles, three studies met the inclusion criteria: two RCTs exhibiting low to medium risk of bias and one N-RCT with low risk of bias. The analysis suggests that enzyme- and protein-enriched toothpastes may contribute to improved gingival health following 12 weeks and 12 months of use. However, the hypothesized effect against extrinsic black stains was not substantiated within the selected studies. These findings, while promising, are constrained by the limited number of included studies, necessitating further investigations to validate these observations and explore the broader implications of enzyme- and protein-based oral care formulations.

Mapping Review of the Correlations Between Periodontitis, Dental Caries, and Endocarditis

Background/Objectives: The correlation between cardiovascular diseases, particularly infective endocarditis, and oral disorders such as periodontitis and dental caries has been widely discussed in the scientific literature. In this mapping review, we aim to examine the available evidence on the link between these conditions, focusing on the pathogenetic mechanisms that underlie the development of endocarditis in patients with oral diseases. Methods: A systematic search was conducted across three major databases-PubMed, Scopus, and ScienceDirect-as well as grey literature in Google Scholar. Relevant articles were selected based on inclusion and exclusion criteria, focusing primarily on systematic reviews. The data extracted included study characteristics, main outcomes, and risk-of-bias evaluations. Results: A total of 13 systematic reviews were included in this mapping review. The findings suggest there is a significant connection between periodontal disease, dental caries, and the incidence of infective endocarditis. The evidence highlights that oral bacteria, particularly Streptococcus species, can enter the bloodstream during daily activities and invasive dental procedures, contributing to the development of endocarditis in susceptible individuals. However, the role of antibiotic prophylaxis in preventing endocarditis following dental procedures remains controversial. Conclusions: This review reinforces the importance of oral health in preventing cardiovascular complications, especially infective endocarditis. Although antibiotic prophylaxis may reduce the risk in high-risk individuals, further research is needed to clarify its effectiveness. Enhanced awareness of and education on the shared risks between oral and cardiovascular health could improve prevention strategies and patient outcomes.

Bioinspired Janus Membrane with Dopamine-ZnO Coating for Antibacterial Filtration in Oral Applications

Developing an oral fibrous barrier membrane that prevents bacterial invasion while possessing antibacterial properties and facilitating fluid decompression remains a significant clinical and scientific challenge. In this study, we developed a novel Janus membrane by modifying a polypropylene (PP) fibrous membrane with dopamine and zinc oxide nanoparticles (ZnO-NPs). Fabricated via a simple floating immersion method, this asymmetric bilayer structure consists of a hydrophobic PP layer and a hydrophilic PP/dopamine@30 nm ZnO layer, providing both antibacterial properties and enhanced fluid filtration. The mechanical properties of the PP/ZnO membrane were significantly enhanced, with an increase in the Young's modulus and ultimate tensile strength, indicating improved strength. Antibacterial activity against Streptococcus mutans (S. mutans) demonstrated a significant reduction in biofilm formation on the PP/dopamine@30 nm ZnO surface compared to unmodified PP. Water flux tests confirmed a stable, high filtration rate, with increased permeability under rising pressure. In vivo experiments with miniature pigs confirmed reduced bacterial presence on the sterile side of the membrane. These findings highlight the potential of the membrane for oral exudate filtration, extending filtration time and minimizing infection risks under strict sterility conditions. Further improvements in barrier properties are necessary to optimize its clinical performance.

Injectable and Conductive Polyurethane Gel with Load-Responsive Antibiosis for Sustained Root Canal Disinfection

To address the limitations of conventional antibacterial therapies, we developed an injectable, conductive polyurethane-based composite gel system for sustained root canal disinfection. This gel incorporates piezoelectric nanoparticles (n-BaTiO3) and conductive segments (aniline trimer, AT) within a polyurethane matrix, which synergistically interact with a static antimicrobial agent (n-ZnO) to achieve dynamic, mechano-responsive antibacterial activity. Under cyclic compression (simulating mastication), the piezoelectric gels exhibited enhanced electroactivity via the mechano-electric coupling effect, generating 2-fold higher voltage and a 1.8-1.9× increase in current compared to non-piezoelectric controls. The dynamic electroactivity of the gels enabled superior long-term performance, achieving 92-97% biofilm eradication, significantly higher than the static n-ZnO-only gel (88%). XPS and UV-vis spectroscopy analyses confirmed mechano-electrochemically amplified reactive oxygen species (ROS) generation, which contributed to improved biofilm disruption. The ISO-compliant gel provides durable, load-responsive disinfection while maintaining good biocompatibility, offering a promising solution to prevent post-treatment reinfection.

Influence of orthodontic appliances and nitrate on the oral microbiota

In this pilot study, we investigated the bacterial changes introduced on the subgingival, tongue, and saliva microbiota during fixed orthodontic treatment, with or without daily administration of nitrate-containing beet juice for 2 weeks in 22 individuals with good general health. We followed clinical parameters in combination with microbiota changes before, after 2 weeks, and after 6 months of treatment with fixed orthodontic appliances. In accordance with variations in community composition at the sampling sites, effects to orthodontic treatment differed. Subgingival communities responded promptly to orthodontic treatment with no additional structural changes over time, whereas saliva and tongue communities were affected only after extended treatment. Periodontal pathogens such as Selenomonas sputigena were enriched in subgingival communities, whereas Streptococcus mutans was enriched in saliva. Specifically, Rothia mucilaginosa increased tremendously in relative abundance in both tongue and saliva communities. The effect of beet juice on microbial composition was significant in subgingival samples even though the differences were not mirrored in single differentially distributed genera or species. This indicates changes in the complete subgingival microbial net of interacting species. However, the prevention of Corynebacterium matruchotii enrichment by beet juice may be important for prevention of biofilm formation. Enrichment of Neisseria flavescens group bacteria and Abiotrophia and depletion of different Actinomyces and Stomatobaculum were observed on tongue communities. We conclude that subgingival microbiota are rapidly affected by fixed orthodontic appliances and can be positively influenced by regular administration of nitrate-containing juice. KEY POINTS: • The subgingival site, tongue, and saliva contain different microbiota • The microbiota react differently to orthodontic treatment and beet juice • Key genera and species affected by treatments were identified.

Effective treatment of oral microbial infections and biofilm using flavonoid rutin - An in vitro study

Background

Oral microbial infections and biofilm-associated conditions, such as dental caries, gingivitis, and periodontitis, remain major challenges in oral healthcare. Biofilms provide resistance to conventional antimicrobial treatments, necessitating innovative solutions. This study investigates rutin, a flavonoid glycoside, for its antimicrobial and antibiofilm properties against key oral pathogens.

Aim

To evaluate the antibacterial and antibiofilm efficacy of rutin against oral pathogens, including Streptococcus mutans, Pseudomonas aeruginosa, and Candida albicans, and assess its hemocompatibility as a safe therapeutic agent.

Methodology

Oral pathogens were isolated from clinical samples and identified using the VITEK®2 Compact System. Antimicrobial activity of five flavonoids was screened using the well diffusion method, with rutin demonstrating the highest efficacy. Minimum inhibitory concentration (MIC) and antibiofilm activity were assessed using broth microdilution and crystal violet staining, respectively. Confocal Laser Scanning Microscopy analyzed live/dead cells in treated biofilms. Hemocompatibility was evaluated via a hemolysis assay.

Results

Rutin exhibited significant antimicrobial activity with zone of inhibition as 19 mm (C. albicans), 17 mm (P. aeruginosa), and 17 mm (S. mutans). MIC against mixed biofilms was 10 mM, while treatment at 2 × MIC reduced biofilm biomass by 92 %. Live/dead analysis confirmed extensive microbial cell death in biofilms. Hemolysis rates below 5 % established rutin's biocompatibility.

Conclusion

Rutin demonstrates potent antimicrobial and antibiofilm efficacy with excellent safety, suggesting its potential as an alternative therapy for biofilm-associated oral infections. Further in vivo studies are warranted to validate these findings.

Devices to overcome the buccal mucosal barrier to administer therapeutic peptides

Peptide therapeutics are important in healthcare owing to their high target specificity, therapeutic efficacy, and relatively low side effect profile. Injections of these agents have improved thetreatment of chronic diseases including autoimmune, metabolic disorders, and cancer. However, their administration via injections can prove a barrier to patient acceptability of treatments. While oral delivery of these molecules is preferable, oral peptide formulations are associated with limited bioavailability due to degradation in the intestine and low epithelial permeability. Buccal administration of peptides is a potential alternative to injections and oral formulations. Similar to the oral route, the buccal route can promote better patient adherence to dosing regimens, along with the added advantages of not requiring restriction on food or drink consumption before and after administration, as well as avoidance of the liver first-pass metabolism. However, like oral, effective buccal absorption of peptides is still challenging due to the high epithelial permeability barrier. We present a multidisciplinary approach to understanding the buccal physiological barrier to macromolecule permeation and discuss how engineered devices may overcome it. Selected examples of buccal devices can facilitate fast and efficient macromolecule absorption through multiple mechanisms including physical disruption of epithelia, convection-based mass transfer, and a combination of physicochemical strategies. Importantly, minimally invasive devices can be self-applied and are associated with the maintenance of the barrier after exposure. We analysed the critical attributes that are required forthe clinical translation of buccal peptide administration devices. These include performance-driven device development, manufacturing features, patient acceptability, and commercial viability.

Evaluation of Deformation and Antibacterial Properties of Dental Alginates Mixed with Silver Nanoparticles

This study aimed to evaluate the effect of the incorporation of silver nanoparticles (AgNPs) of 5.57 nm size into dental alginates on their deformation and antimicrobial properties. Six experimental groups were prepared: 2 different alginates with 0.25 wt% AgNPs, 2 different alginates with 0.5 wt% AgNPs (5.57 nm), and 2 unmodified control alginate groups. The presence of AgNPs was confirmed using X-ray diffraction analysis with a Bruker D8 Advance diffractometer. Antimicrobial activity was evaluated using the Kirby-Bauer disk diffusion method (direct contact) against E. coli and S. aureus cultures incubated on Mueller-Hinton (M-H) agar at 37 °C for 24 h. The results demonstrated that the addition of 0.25% and 0.5% AgNPs significantly enhanced the antimicrobial properties of alginate (p < 0.05), showing clear inhibition zones against the tested microorganisms. In terms of mechanical properties, AgNPs-modified samples exhibited improved elastic recovery compared to the control group (p > 0.05). These findings suggest that incorporating silver nanoparticles into alginates could enhance their antimicrobial properties without compromising the mechanical integrity required for dental applications.

OSaMPle workflow for salivary metaproteomics analysis reveals dysbiosis in inflammatory bowel disease patients

The human oral microbiome has been associated with multiple inflammatory conditions including inflammatory bowel disease (IBD). Identifying functional changes in oral microbiome by metaproteomics helps understanding the factors driving dysbiosis related to intestinal diseases. However, enriching bacterial cells from oral samples (such as saliva and mouth rinse) rich in host proteins is challenging. Here, we present an Optimized Salivary MetaProteomic sample analysis workflow (OSaMPle) to enrich salivary bacteria and reduce host-derived interferences for in-depth analysis of the oral metaproteome. Compared to a conventional approach, OSaMPle improved the identification of bacterial peptides and proteins by 3.2 folds and 1.7 folds, respectively. Furthermore, applying OSaMPle to analyze mouth rinse samples from IBD patients revealed significant alterations in bacterial protein expressions under disease conditions. Specifically, proteins involved in the fatty acid elongation pathway in Peptostreptococcus were significantly less abundant in IBD patients, whereas proteins associated with the TCA cycle in Neisseria were significantly more abundant. The OSaMPle workflow is capable of processing small-volume oral samples and adaptable to high-throughput automation. It holds promise as a strategy for investigating the functional responses of oral microbiomes under disease conditions and identifying disease-associated microbes with their proteins, providing critical insights for detecting disease-related biomarkers within the oral microbiome.

Diazotrophic community difference between specialists and generalists in response to arsenic and antimony contaminations

Diazotrophs are pivotal in bioremediation, particularly in environments contaminated by metal(loid)s. Despite their significance, the specific impacts of such contamination on the diverse functional groups of soil diazotrophs, including both generalists and specialists, are not well understood. Our study examines the influences of antimony and arsenic contamination on the ecological functions of these diazotrophic groups in areas with high (HC) and low (LC) contamination. Utilizing geochemical analyses, nitrogenase gene (nifH) sequencing, and robust statistical approaches, we assessed the composition and distribution patterns of diazotrophs across different contamination levels. Our results show consistent alpha diversity among diazotrophic subcommunities in both HC and LC sites, highlighting their resilience to metal-induced stress. Generalists exhibited significant compositional shifts between HC and LC sites, whereas specialists remained stable. Network analyses revealed that specialists more frequently occupy central roles than generalists, yet metal stress displaces both groups from these positions within the networks. Deterministic processes were identified as the dominant factors influencing community assembly for both subcommunities. While MST values suggested a similar balance of deterministic and stochastic processes between HC and LC sites, the findings indicate that metal(loid) contamination may still contribute to ecological selection, particularly through Sb and As influencing generalist and specialist composition. These results provide valuable insights into the differential responses of generalist and specialist subcommunities to metal contamination, informing improved ecosystem management and bioremediation strategies.

Saccharibacteria (TM7) in saliva and subgingival microbiome as a predictor for gingivitis in individuals with type2 diabetes evaluated by qPCR

Oral samples are widely used for studying oral microbiome in health and diseases. In this study, saliva and subgingival biofilm (SGB) samples obtained from patients with type2 diabetes (T2DM), without periodontitis (G1 group), with gingivitis (G2 group), and periodontitis (G3 group), were used to compare the abundance of Saccharibacteria (TM7), its host's bacteria (Schaalia odontolytica), periodontopathogen (Represented by Fusobacterium nucleatum), and nitrate-reducing bacteria (represented by Rothia mucilaginosa). The gingival crevicular fluid were also used to analyze the transcription levels of interleukin-6 (IL-6) and C-reactive protein (CRP). Healthy individuals' oral samples served as a control, and the targeted bacteria and inflammatory indicators were detected and measured using real-time PCR. The results showed that in either sample, the abundance of TM7 and other targeted bacteria showed a similar profile. Notably, within participants with T2DM, the abundance of TM7 was similar in G1 and G2 groups, but significantly decreased in G3 group. With the exception of the SGB of the G3 group, the relationship between TM7 and its bacterial host was strongly positive across all evaluated samples. Furthermore, CRP had higher transcription levels than IL-6 across the entire group. Despite the fact that the G3 group showed an adverse relationship between TM7 and CRP, patients with T2DM generally showed a positive correlation between TM7 and IL-6/CRP, which was verified by a receiver operating curve.

Analysis of the Primary Pathogenic Bacteria in Abscess Disease of Musk Deer Using Metagenomic Approaches

Abscesses are among the diseases affecting the survival of captive musk deer and are difficult to identify in their early stages. In this study, metagenomic sequencing, 16S rRNA sequencing, and paraffin sectioning were used to analyze the microbiota in the abscess musk deer pus group (AMP), abscess musk deer oral group (AMO), and healthy musk deer oral group (HMO) to compare the differences in microbiota in musk deer. By detecting differences in the oral microbiota through throat swabs, we aimed to monitor the early onset of abscess disease to facilitate timely intervention and treatment. The results showed that the alpha diversity of HMO microbiota was significantly higher than that of the AMP and AMO samples. Beta diversity results indicated that there were significant differences in the bacterial communities of HMO and AMO samples, and no significant difference was found between AMO and AMP samples. A taxonomic analysis of the bacterial species indicated that differences between HMO and AMP groups were found in the Fusobacterium and Trueperella species. Fusobacterium and Trueperella were the main pathogenic bacteria responsible for the occurrence of abscess diseases in forest musk deer in this study. Furthermore, the appearance of Fusobacterium and Trueperella in the oral cavity can serve as biomarkers for the early diagnosis of abscess disease in musk deer.

High prevalence of antibiotic resistance of Streptococcus species in saliva from non-hospitalized adults - a pilot study

Background

Antibiotic resistance (AR) is a recognized threat to global human health. However, the prevalence of AR in healthy adults is not well described. The present observational pilot study aimed to uncover the potential of using saliva samples for screening for antibiotic resistance.

Methodology

A laboratory protocol was developed for screening of AR in saliva samples, which was tested and validated using saliva samples collected from 100 study participants. The risk of AR was analyzed with descriptive statistics and evaluated using a risk-factor profile based on information on antibiotic usage within the last 12 months, education level and origin of birth.

Results

AR was identified in 43 (48%) saliva samples, out of which 60,0% and 17,1% of resistant strains displayed resistance to clindamycin and penicillin, respectively. Streptococcus salivarius and Streptococcus parasanguinis were most often identified with AR (51,4% of all cases). The risk of AR was not associated with self-perceived oral or general health, antibiotic use within the latest 12 months or any demographic or socioeconomic parameters recorded. The risk-factor profile was observed in 44% in the AR group versus 30% in the non-AR group (p = 0.19).

Conclusion

The present study showed that it is possible to perform non-invasive saliva-based screening for AR with a frequency of 48% of the samples, highlighting that saliva samples could be a valuable supplement to current surveillance methodologies for AR in the oral microbiota.

Eight weeks of high-intensity interval training alters the tongue microbiome and impacts nitrate and nitrite levels in previously sedentary men

Nitric oxide (∗NO) is a key signalling molecule, produced enzymatically via ∗NO synthases (NOS) or following the stepwise reduction of nitrate to nitrite via oral bacteria. Exercise training upregulates NOS expression and improves systemic health, but its effect on oral health, and more particularly the oral microbiome, has not been investigated. We used an exercise training study design to investigate changes in the tongue dorsum microbiome, and in nitrate and nitrite levels in the saliva, plasma and muscle, before, during and after an exercise training period. Eleven untrained males (age 25 ± 5 years, mass 64.0 ± 11.2 kg, stature 171 ± 6 cm, V˙ O2peak 2.25 ± 0.42 l min-1) underwent 8-weeks of high-intensity interval training (HIIT), followed by 12-weeks of detraining. The tongue dorsum microbiome was examined using Pac-Bio long-read 16S rRNA sequencing. Nitrate and nitrite levels were quantified with high-performance liquid chromatography. Grouped nitrite-producing species did not change between any timepoints. However, HIIT led to changes in the microbiome composition, increasing the relative abundance of some, but not all, nitrite-producing species. These changes included a decrease in the relative abundance of nitrite-producing Rothia and a decrease in Neisseria, alongside changes in 6 other bacteria at the genus level (all p ≤ 0.05). At the species level, the abundance of 9 bacteria increased post-training (all p ≤ 0.05), 5 of which have nitrite-producing capacity, including Rothia mucilaginosa and Streptococcus salivarius. Post-detraining, 6 nitrite-producing species remained elevated relative to baseline. Nitrate increased in plasma (p = 0.03) following training. Nitrite increased in the saliva after training (p = 0.02) but decreased in plasma (p = 0.03) and muscle (p = 0.002). High-intensity exercise training increased the abundance of several nitrite-producing bacteria and altered nitrate and nitrite levels in saliva, plasma, and muscle. Post-detraining, several nitrite-producing bacteria remained elevated relative to baseline, but no significant differences were detected in nitrate or nitrite levels. Switching from a sedentary to an active lifestyle alters both the microbiome of the tongue and the bioavailability of nitrate and nitrite, with potential implications for oral and systemic health.

Human and bacterial genetic variation shape oral microbiomes and health

It is largely unknown which human genetic variants shape a person's oral microbiome and potentially promote its dysbiosis. We characterized the oral microbiomes of 12,519 people by analyzing whole-genome sequencing reads from previously sequenced saliva-derived DNA. Human genetic variation at 11 loci (10 novel) associated with differences in oral microbiome composition. Nearly all of these associations implicated candidate genes with readily interpretable functions, several related to carbohydrate availability. The strongest association ( p =3.0x10 -188 ) involved the common FUT2 W154X loss-of-function variant, which associated with the abundances of 32 bacterial species. Human host genetics also appeared to powerfully shape within-species genetic variation in oral bacteria. Variation at the 11 human loci associated with variation in gene dosages in 68 regions of bacterial genomes. Several such associations implicated interactions of bacterial proteins with histo-blood group antigens presented on host mucosal cell surfaces and salivary proteins. Common, multi-allelic copy-number variation of AMY1 , which encodes salivary amylase, associated with oral microbiome composition ( p =1.5x10 -53 ) and with dentures use in UK Biobank ( p =5.9x10 -35 , n=418k), suggesting that amylase abundance impacts oral health by influencing the oral microbiome. Two other microbiome composition-associated loci, FUT2 and PITX1 , also significantly associated with dentures risk, collectively nominating numerous microbial taxa that might contribute to tooth decay.

A Population-Based Study of the Association Among Dry Mouth, Vitamin B2, and Mortality

BACKGROUND

Previous studies have indicated that older adults with the symptom of dry mouth have an increased risk of death. B vitamins are strongly linked to oral and systemic health. However, the relationship among dry mouth, vitamin B2 and mortality remains unclear.

OBJECTIVES

This study aimed to investigate the potential relationship among dry mouth, vitamin B2 and mortality.

METHODS

A total of 6183 participants from the US National Health and Nutrition Examination Survey (NHANES) 2011-2014 with information on dry mouth were included at baseline. 4324 normal individuals and 684 individuals with dry mouth were followed up until 31 December 2019. The Cox proportional hazard model was used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations among dry mouth, vitamin B2 and all-cause mortality.

RESULTS

Compared to the population without dry mouth, the risk of all-cause mortality was significantly higher in the population with dry mouth. The multivariable-adjusted HR and 95% CI was 1.41 (1.05, 1.90). The intake of vitamin B2 can significantly reduce the risk of death in participants with dry mouth, but not in participants without dry mouth. The HR and 95% CI of all-cause mortality in the highest vitamin B2 intake group was 0.37 (0.19, 0.73) compared to the lowest intake group.

CONCLUSIONS

Individuals with dry mouth suffered a significantly higher risk of all-cause mortality compared to those without dry mouth. Higher intake of vitamin B2 was apparently associated with a lower risk of all-cause mortality in the population with dry mouth.

Decoding Salivary ncRNAomes as Novel Biomarkers for Oral Cancer Detection and Prognosis

Oral cancer (OC) ranks among the most prevalent head and neck cancers, becoming the eleventh most common cancer worldwide with ~350,000 new cases and 177,000 fatalities annually. The rising trend in the occurrence of OC among young individuals and women who do not have tobacco habits is escalating rapidly. Surgical procedures, radiation therapy, and chemotherapy are among the most prevalent treatment options for oral cancer. To achieve better therapy and an early detection of the cancer, it is essential to understand the disease's etiology at the molecular level. Saliva, the most prevalent body fluid obtained non-invasively, holds a collection of distinct non-coding RNA pools (ncRNAomes) that can be assessed as biomarkers for identifying oral cancer. Non-coding signatures, which are transcripts lacking a protein-coding function, have been identified as significant in the progression of various cancers, including oral cancer. This review aims to examine the role of various salivary ncRNAs (microRNA, circular RNA, and lncRNA) associated with disease progression and to explore their functions as potential biomarkers for early disease identification to ensure better survival outcomes for oral cancer patients.

Distribution and Characteristics of Oral Pathogens According to Blood Glucose Levels in South Korean Health Examinees

The distribution of oral pathogens is influenced by genetic background, diet, socioeconomic status, and racial factors. This study aimed to assess the distribution and characteristics of oral pathogens based on blood glucose levels in a South Korean population. This cross-sectional, retrospective study included subjects from 17 health promotion centers in 13 South Korean cities between November 2021 and December 2022. Real-time multiplex PCR was used to detect 10 periodontitis-related pathogens, 6 dental caries-related pathogens, and 1 dental caries-protective bacterium. The most prevalent periodontitis-related pathogens were Parvimonas micra (97.6%), Porphyromonas endodontalis (96.8%), and Treponema socranskii (95.0%). Among dental caries-related pathogens, Streptococcus sanguinis and Veillonella parvula were found in all subjects. The prevalence of periodontitis-related pathogens was higher in males, while pathogens related to periodontitis and dental caries were more prevalent in older individuals. In the diabetes group, Aggregatibacter actinomycetemcomitans, red and orange complexes, and Streptococcus mutans were more prevalent. The relative amount of S. sanguinis was lower, while V. parvula was higher in individuals with diabetes mellitus. The prevalence and composition of oral pathogens vary by sex, age, and blood glucose levels. Diabetic individuals showed a pathogenic community structure linked to increased risks of periodontitis and dental caries.

Investigation of the cleaning performance of commercial orthodontic cleaning tablets regarding biofilm removal on PMMA test specimens : An ex vivo study

PURPOSE

The purpose of this ex vivo study was to compare the cleaning performance of three commercially available orthodontic cleaners on polymethyl methacrylate (PMMA) test specimens covered with biofilm.

METHODS

Twenty subjects wore an individually manufactured vacuum-formed maxillary splint with four integrated PMMA test specimens for 7 days. The four test specimens were located on the buccal surfaces of the maxillary molars. After a 7-day wearing period, the PMMA test specimens colonized by biofilm were divided into two halves. One half was placed in 150 ml of tap water or in 150 ml of cleaning solution of the cleaners Retainer Brite® (Dentsply International Raintree Essix, Sarasota, FL, USA), Kukis® Xpress (Reckitt Benckiser, Heidelberg, Germany) or Dontodent (Propack, Heidelberg, Germany) while the other half remained uncleaned. The modified o‑phthaldialdehyde (OPA) method was used to determine the amount of protein on both halves of the test specimens. The difference was tested for significance as a measure of the cleaning effect using a paired sample t‑test.

RESULTS

The cleaning performance of the three orthodontic cleaners was higher than the cleaning performance of tap water (mean 25.9 ± 6.5%). While Retainer Brite® (mean 54.5 ± 7.1%) removed significantly more biofilm than Dontodent (mean 41.5 ± 9.2%, p < 0.001) and Kukis® Xpress (mean 39.9 ± 11.5%, p < 0.001), there was no significant difference in the cleaning performance between Kukis® Xpress and Dontodent (p = 1).

CONCLUSION

Seven-day-old biofilm is only removed partially by the investigated orthodontic cleaners, so that they are not suitable as the only measure for removing established biofilms.

Probiotics and gut microbiota modulation: implications for skin health and disease management

The gut microbiota, consisting of a varied population of microorganisms in the digestive tract, is essential for sustaining overall human health, encompassing skin health. This review explored the intricate relationship between gut microbiota and various skin disorders, investigating the pathways through which gut dysbiosis may have impacted the development and progression of these conditions. We focused on the impact of gut microbiota on atopic dermatitis, psoriasis, acne vulgaris, acne rosacea, and melanoma. The review highlighted the potential of probiotics as a therapeutic strategy for modulating gut microbiota composition and, consequently, improving skin health. We discussed the evidence supporting the use of probiotics in managing these skin disorders and explored the mechanisms by which probiotics delivered their positive effects. Finally, we discussed the potential role of gut microbiota in other skin diseases, emphasizing the need for further research to unravel the complex interplay between the gut and the skin. Significant gaps remain in understanding the gut-skin axis, how microbial interactions contribute to skin disorders, and how to effectively manipulate the microbiome for therapeutic purposes. This review provided extensive research on the gut-skin axis, highlighting the promising prospects of modulating gut microbiota as a therapeutic strategy for various dermatological conditions.

Causal relationship between gut microbiota and dental caries: A Mendelian randomization analysis

The onset of dental caries is associated with multiple factors, including oral microbiota, dietary sugars, the defensive mechanisms of saliva and teeth, oral hygiene practices, and socioeconomic factors. However, its relationship with the gut microbiota remains to be further explored. It remains crucial to establish a definitive causal link between the gut microbiota and the development of dental caries. This study aimed to investigate the causal relationship between gut microbiota and the risk of dental caries, focusing on identifying specific microbial communities potentially implicated in its pathogenesis. Gut microbiota data from genome-wide association studies (GWAS) conducted by the MiBioGen consortium were utilized as the exposure variable, with dental caries as the outcome variable. A Mendelian randomization (MR) approach was employed, leveraging comprehensive, publicly available GWAS summary data from European populations. The primary analytical method was the inverse variance weighted method, supplemented by additional techniques such as the weighted median model, MR-Egger, simple mode, and weighted mode, to ensure the robustness of the results. Heterogeneity was evaluated using Cochran Q test, and potential pleiotropy was assessed through MR-Egger regression. Sensitivity analyses were performed using the leave-one-out method to further validate the findings. The results revealed that a higher relative abundance of Christensenellaceae, FamilyXIII, Ruminococcaceae, and Senegalimassilia was associated with a reduced risk of dental caries. In contrast, a higher relative abundance of Erysipelotrichia, Erysipelotrichales, Pasteurellales, Erysipelotrichaceae, Pasteurellaceae, Methanobrevibacter, Roseburia, and Terrisporobacter was linked to an elevated risk of dental caries. This study provides compelling evidence for a causal relationship between gut microbiota and the development of dental caries, offering novel insights into the potential role of specific gut microbial communities in the pathogenesis of dental caries.

Effectiveness of Herbal Medicines with Anti-Inflammatory, Antimicrobial, and Antioxidant Properties in Improving Oral Health and Treating Gingivitis and Periodontitis: A Systematic Review

OBJECTIVES

This systematic review investigates the effectiveness of natural extracts with anti-inflammatory properties for improving oral health, particularly in managing gingivitis and periodontal disease (PD). With PD being a major global health issue, exacerbated by microbial dysbiosis and oxidative stress, the integration of phytochemicals and herbal formulations into periodontal therapy offers a promising avenue for adjunctive treatments.

METHODS

A systematic review was conducted following PRISMA guidelines and registered under the International Prospective Register of Systematic Reviews (ID: 641944). Databases, including PubMed, Scopus, and Web of Science, were searched between 18-24 December 2024, using Boolean keywords combining terms such as "herbal medicine", "plant extracts", "anti-inflammatory", and "periodontal therapy". Studies involving animal models, in vitro data, or non-peer-reviewed articles were excluded.

RESULTS

Seventeen studies met inclusion criteria. Polyherbal formulations and single-component extracts (e.g., Camellia sinensis, Punica granatum, Zingiber officinale, and Rosmarinus officinalis) demonstrated comparable efficacy to conventional agents like chlorhexidine (CHX). Polyherbal rinses, camellia sinensis gels, and extracts like Punica granatum reduced inflammation, improved gingival health, and showed antimicrobial properties, offering effective natural alternatives.

CONCLUSIONS

Natural products, including single extracts and polyherbal formulations, provide effective and safe alternatives for managing gingivitis and PD. Their anti-inflammatory, antimicrobial, and antioxidant properties support their adjunctive role alongside with scaling and root planning therapy (SRP) in periodontal therapy. However, further large-scale, long-term studies are needed to standardize formulations and establish optimal protocols.

Exploring AI-Driven Machine Learning Approaches for Optimal Classification of Peri-Implantitis Based on Oral Microbiome Data: A Feasibility Study

Background: Machine learning (ML) techniques have been recently proposed as a solution for aiding in the prevention and diagnosis of microbiome-related diseases. Here, we applied auto-ML approaches on real-case metagenomic datasets from saliva and subgingival peri-implant biofilm microbiomes to explore a wide range of ML algorithms to benchmark best-performing algorithms for predicting peri-implantitis (PI). Methods: A total of 100 metagenomes from the NCBI SRA database (PRJNA1163384) were used in this study to construct biofilm and saliva metagenomes datasets. Two AI-driven auto-ML approaches were used on constructed datasets to generate 100 ML-based models for the prediction of PI. These were compared with statistically significant single-microorganism-based models. Results: Several ML algorithms were pinpointed as suitable bespoke predictive approaches to apply to metagenomic data, outperforming the single-microorganism-based classification. Auto-ML approaches rendered high-performing models with Receiver Operating Characteristic-Area Under the Curve, sensitivities and specificities between 80% and 100%. Among these, classifiers based on ML-driven scoring of combinations of 2-4 microorganisms presented top-ranked performances and can be suitable for clinical application. Moreover, models generated based on the saliva microbiome showed higher predictive performance than those from the biofilm microbiome. Conclusions: This feasibility study bridges complex AI research with practical dental applications by benchmarking ML algorithms and exploring oral microbiomes as foundations for developing intuitive, cost-effective, and clinically relevant diagnostic platforms.

The forgotten link: how the oral microbiome shapes childhood growth and development

Childhood stunting, defined as impaired linear growth and development, remains a significant global health challenge with long-term consequences on cognitive and physical well-being. Emerging evidence highlights the pivotal role of the oral microbiome-a dynamic microbial ecosystem-in influencing nutritional status, immune response, and overall systemic health. This review explores the intricate interplay between the oral microbiome and stunting, emphasizing mechanisms such as microbial dysbiosis, its impact on nutrient absorption, and immune modulation. Disruptions in the oral microbiome can lead to nutrient malabsorption and systemic inflammation, further exacerbating growth impairments in children. Furthermore, the potential for microbiome-targeted diagnostics and interventions, including probiotics and prebiotics, offers novel strategies to address stunting. A deeper understanding of these interactions may inform innovative diagnostic tools and therapeutic interventions aimed at mitigating stunting through oral microbiome modulation. Integrating oral microbiome research into stunting prevention efforts could provide valuable insights for public health strategies to improve child growth and development, particularly in resource-limited settings. Future research should focus on elucidating the molecular pathways linking the oral microbiome to stunting and developing personalized interventions that optimize microbiome health in early life.

The role of salivary metabolomics in chronic periodontitis: bridging oral and systemic diseases

BACKGROUND

Chronic periodontitis is a condition impacting approximately 50% of the world's population. As chronic periodontitis progresses, the bacteria in the oral cavity change resulting in new microbial interactions which in turn influence metabolite production. Chronic periodontitis manifests with inflammation of the periodontal tissues, which is progressively developed due to bacterial infection and prolonged bacterial interaction with the host immune response. The bi-directional relationship between periodontitis and systemic diseases has been reported in many previous studies. Traditional diagnostic methods for chronic periodontitis and systemic diseases such as chronic kidney diseases (CKD) have limitations due to their invasiveness, requiring practised individuals for sample collection, frequent blood collection, and long waiting times for the results. More rapid methods are required to detect such systemic diseases, however, the metabolic profiles of the oral cavity first need to be determined.

AIM OF REVIEW

In this review, we explored metabolomics studies that have investigated salivary metabolic profiles associated with chronic periodontitis and systemic illnesses including CKD, oral cancer, Alzheimer's disease, Parkinsons's disease, and diabetes to highlight the most recent methodologies that have been applied in this field.

KEY SCIENTIFIC CONCEPTS OF THE REVIEW

Of the rapid, high throughput techniques for metabolite profiling, Nuclear magnetic resonance (NMR) spectroscopy was the most applied technique, followed by liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS). Furthermore, Raman spectroscopy was the most used vibrational spectroscopic technique for comparison of the saliva from periodontitis patients to healthy individuals, whilst Fourier Transform Infra-Red Spectroscopy (FT-IR) was not utilised as much in this field. A recommendation for cultivating periodontal bacteria in a synthetic medium designed to replicate the conditions and composition of saliva in the oral environment is suggested to facilitate the identification of their metabolites. This approach is instrumental in assessing the potential of these metabolites as biomarkers for systemic illnesses.

The Oral Microbiome and Systemic Health: Bridging the Gap Between Dentistry and Medicine

The oral microbiome, consisting of a mixture of bacteria, fungi, and viruses, is an important contributor to oral and systemic health. Microbial balance disruptions are associated with oral pathologies like dental caries and periodontitis as well as systemic diseases such as cardiovascular diseases, adverse pregnancy outcomes, and respiratory diseases. This review explores the mechanistic pathways linking oral dysbiosis to systemic inflammation, endothelial dysfunction, and immune modulation. The roles of key microbial species in health and disease are analyzed, with an emphasis on how hematogenous dissemination leads to systemic pathologies through inflammatory signaling. Also, advances in high throughput sequencing are discussed, as well as microbial diversity and its implications for diagnostics and therapeutics. The review highlights the potential of oral microbiota-targeted interventions to mitigate systemic diseases through dentistry and medicine integration, by throwing light on interdisciplinary strategies. Future work should focus on the evaluation of the mechanisms by which the oral microbiome plays a role in systemic diseases through the integration of multi-omics approaches such as metagenomics, transcriptomics, and metabolomics. Furthermore, clinical trials need to be designed in a way to evaluate the efficacy of microbiome-targeted therapies in the prevention of cardiovascular diseases, adverse pregnancy outcomes, and autoimmune disorders.

Botanicals as promising antimicrobial agents for enhancing oral health: a comprehensive review

The mouth houses the second largest diversity of microorganisms in the body, harboring more than 700 bacterial species colonizing the soft mucosa and hard tooth surfaces. Microbes are the cause of several health-related problems, such as dental carries, gingivitis, periodontitis, etc., in the mouth across different age groups and socioeconomic/demographic groups. Oral infections are major health problems that affect the standard of living. Compromised oral health is related to chronic conditions and systemic disorders. Microbes responsible for dental caries are acid-producing and aciduric Gram-positive bacteria (Streptococci, Lactobacilli). Gram-negative bacteria (Porphyromonas, Prevotella, Actinobacillus, and Fusobacterium) capable of growing in anaerobic environments are responsible for periodontal diseases. Due to the high prevalence of oral diseases, negative effects associated with the use of antimicrobial agents and increased antibiotic resistance in oral pathogens, suitable alternative methods (effective, economical and safe) to suppress microbes disturbing oral health need to be adopted. Side effects associated with the chemical antimicrobial agents are vomiting, diarrhea and tooth staining. Several researchers have studied the antimicrobial properties of plant extracts and phytochemicals and have used them as indigenous practices to control several infections. Therefore, phytochemicals extracted from plants can be suitable alternatives. This review focuses on the various phytochemical/plant extracts suppressing the growth of oral pathogens either by preventing their attachment to the surfaces or by preventing biofilm formation or other mechanisms.

Immunological Effects of Electronic Cigarette Use: A Review of Current Evidence

Electronic cigarettes (EC) have emerged as a popular alternative to traditional tobacco products, but their impact on immune function has raised significant health concerns. This review explores the immunological effects of EC exposure, focusing on innate and adaptive immune responses. Electronic cigarette aerosol (ECA) induces widespread inflammation. These changes compromise immune cell function, impairing neutrophil chemotaxis, phagocytosis, and oxidative burst while increasing macrophage and dendritic cell recruitment and activation. ECA also disrupts epithelial barriers, increasing susceptibility to bacterial and viral infections. Studies show enhanced biofilm formation in bacteria such as Staphylococcus aureus and Streptococcus pneumoniae and impaired antiviral responses against pathogens like influenza A and SARS-CoV-2. Additionally, EC exposure modulates adaptive immunity, affecting T and B cell function and increasing systemic inflammatory markers. The long-term consequences of these immunological disruptions include heightened risks for chronic inflammatory diseases, respiratory infections, and potentially autoimmune conditions. The widespread adoption of EC, particularly among younger users, poses a growing public health challenge. As the popularity of vaping continues to rise, these immunological disruptions could result in increased healthcare burdens in the future, with higher rates of infections, chronic inflammatory diseases, and immune system-related disorders among those who begin using e-cigarettes at a young age. Understanding the full scope of EC-related health risks is essential for informing public health policies and protecting future generations from the potential long-term effects of vaping.

Effects of Vegetable and Fruit Juicing on Gut and Oral Microbiome Composition

BACKGROUND

In recent years, juicing has often been promoted as a convenient way to increase fruit and vegetable intake, with juice-only diets marketed for digestive cleansing and overall health improvement. However, juicing removes most insoluble fiber, which may diminish the health benefits of whole fruits and vegetables. Lower fiber intake can alter the microbiota, affecting metabolism, immunity, and mental health, though little is known about juicing's specific effects on the microbiota. This study addresses this gap by exploring how juicing impacts gut and oral microbiome composition in an intervention study.

METHODS

Fourteen participants followed one of three diets-exclusive juice, juice plus food, or plant-based food-for three days. Microbiota samples (stool, saliva, and inner cheek swabs) were collected at baseline, after a pre-intervention elimination diet, immediately after juice intervention, and 14 days after intervention. Moreover, 16S rRNA gene amplicon sequencing was used to analyze microbiota taxonomic composition.

RESULTS

The saliva microbiome differed significantly in response to the elimination diet (unweighted UniFrac: F = 1.72, R = 0.06, p < 0.005; weighted UniFrac: F = 7.62, R = 0.23, p-value = 0.0025) with a significant reduction in Firmicutes (p = 0.004) and a significant increase in Proteobacteria (p = 0.005). The juice intervention diets were also associated with changes in the saliva and cheek microbiota, particularly in the relative abundances of pro-inflammatory bacterial families, potentially due to the high sugar and low fiber intake of the juice-related products. Although no significant shifts in overall gut microbiota composition were observed, with either the elimination diet or the juice intervention diets, bacterial taxa associated with gut permeability, inflammation, and cognitive decline increased in relative abundance.

CONCLUSIONS

These findings suggest that short-term juice consumption may negatively affect the microbiota.

Evaluation of early bacterial adhesion on CAD/CAM dental materials: an in situ study

The aim of this research was to determine if there are differences in early bacterial adhesion among CAD/CAM dental materials after 24 h exposure in the oral environment. One hundred twenty specimens were prepared according to the manufacturer's recommendations and divided into six groups: RBC (resin-based composite), PMMA (polymethyl methacrylate), PEEK (polyether ether ketone), ZP (zirconia polished), ZG (zirconia glazed), and cobalt-chromium alloy (CoCr alloy). Twenty healthy participants were instructed to carry an intraoral device with six specimens, one per group, for 24 h. Thereafter, real-time polymerase chain reaction (qPCR) and scanning electron microscopy (SEM) analyses enabled quantification and 2D view of biofilm formed on the specimens' surfaces. Kruskal-Wallis test and Dunn's post hoc analysis were used for inter-group comparison and data were presented as median (minimum-maximum). RBC specimens accumulated less bacteria, in comparison with ZG (p = 0.017) and PEEK specimens (p = 0.030), that dominated with the highest amount of adhered bacterial biofilm. PMMA, CoCr, and ZP specimens adhered more bacteria than RBC (p > 0.05), and less than ZG (p > 0.05) and PEEK (p > 0.05). The bacterial number varied considerably among participants. The obtained results enable a closer view into the susceptibility of CAD/CAM materials to microorganisms during the presence in the oral environment, which can be beneficial for a proper selection of these materials for a variety of dental restorations.

Symbiosis Between the Oral Microbiome and the Human Host: Microbial Homeostasis and Stability of the Host

The oral cavity presents a highly diverse microbial composition. All the three domains of life, Bacteria, Eukarya, and Archaea, as well as viruses constitute the oral microbiome. Bacteria are among the most abundant microorganisms in the oral cavity, followed by viruses, fungi, and Archaea. These microorganisms tend to live in harmony with each other and with the host by preventing the colonization of oral sites by exogenous microorganisms. Interactions between the host and its microbiota are crucial for keeping ecological stability in the oral cavity and a condition compatible with oral health. This chapter focuses on describing the oral microbiota in healthy individuals based on both targeted and nontargeted genome sequencing methods and the functional activity played by those microorganisms based on metagenomic, metatranscriptomic, metaproteomic, and metabolomic analyses. Additionally, this chapter explores mutualistic and antagonistic microbe-microbe relationships. These interactions are mediated by complex mechanisms like cross-feeding networks, production of bacteriocins and secondary metabolites, synthesis of pH-buffering compounds, and the use of universal signaling molecules. At last, the role played by host-microbe interactions on colonization resistance and immune tolerance will help provide a better understanding about the harmonious and peaceful coexistence among host and microbial cells under oral health-related conditions.

Interaction of the Systemic Inflammatory State, Inflammatory Mediators, and the Oral Microbiome

Humans are biological units that host numerous microbial symbionts and their genomes, which together form a superorganism or holobiont. Changes in the balance of the oral ecosystem can have consequences for both general and oral health, such as cavities, gingivitis, and periodontitis. Periodontitis is initiated by a synergistic and dysbiotic microbial community that causes local inflammation and destruction of the tooth's supporting tissues, potentially leading to systemic inflammation. This inflammation caused by periodontal disease has been associated with various systemic alterations, and the immune system is largely responsible for the body's exacerbated response, which can induce and exacerbate chronic conditions. Studies indicate that subgingival microorganisms found in periodontitis reach the bloodstream and are distributed throughout the body and, therefore, can be found in distant tissues and organs. Among all diseases associated with periodontal disease, diabetes mellitus presents the strongest and most elucidated link, and its bidirectional relationship has already been demonstrated. Chronic hyperglycemia favors the worsening of periodontal parameters, while the aggravation of periodontal parameters can promote an increase in glycemic indexes. Other systemic diseases have been related to periodontitis, such as Alzheimer's, chronic kidney disease, atherosclerosis, and respiratory diseases. The importance of periodontal control may suggest a reduction in the chances of developing chronic inflammatory diseases because these two alterations often share inflammatory pathways and, for this reason, may influence each other.

Oral Microbiome Dysbiosis and Citrullination in Rheumatoid Arthritis

Rheumatoid arthritis and periodontal diseases, both characterized by chronic inflammation, share many common risk factors, sparking interest in understanding their established association. Emerging research has shed light on the link between these two diseases potentially occurring through the intricate interactions within the oral microbiome. The enrichment of pathogenic strains and species in this microbial community disrupts the delicate balance of both ecological and immunological homeostasis with the host. Particular attention has been paid to the role of key pathogens, such as Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans, known for their immunomodulatory abilities. The generation of an autoimmune response against proteins modified by citrullination is known to be a key step in the pathogenesis of RA. Importantly, the bidirectional citrullination mediated by both host innate immune cells and oral bacteria generates citrullinated peptide neoepitopes, which may serve as potential triggers for the loss of tolerance and subsequent autoimmunity in susceptible individuals. This review highlights the importance of understanding the mechanisms through which oral microbiome dysbiosis and citrullination contribute to the onset and progression of RA. Insights into these mechanisms not only advance pathobiological understanding but also offer potential therapeutic targets. Furthermore, we discuss the potential impact of nonsurgical periodontal treatment in modifying disease progression or mitigating RA, underscoring the critical role of periodontal health in managing systemic inflammatory conditions.

Periodontal disease and cirrhosis: current concepts and future prospects

Periodontal diseases are prevalent among the general population and are associated with several systemic conditions, such as chronic kidney disease and type 2 diabetes mellitus. Chronic liver disease and cirrhosis have also been linked with periodontal disease, an association with complex underlying mechanisms, and with potential prognostic implications. Multiple factors can explain this relevant association, including nutritional factors, alcohol consumption, disruption of the oral-gut-liver axis and associated dysbiosis. Additionally, patients with liver disease have been observed to exhibit poorer oral hygiene practices compared with the general population, potentially predisposing them to the development of periodontal disease. Therefore, it is recommended that all patients with liver disease undergo screening and subsequent treatment for periodontal disease. Treatment of periodontal disease in patients with cirrhosis may help reduce liver-derived inflammatory damage, with recent research indicating a potential benefit in terms of reduced mortality. However, further studies on periodontal disease treatment in patients with liver disease are still warranted to determine optimal management strategies. This narrative review describes current concepts on the association between periodontal disease and chronic liver disease.

Nitrate and nitrite bioavailability in plasma and saliva: Their association with blood pressure - A systematic review and meta-analysis

In this study, we conducted a systematic review and meta-analysis to determine plasma and salivary nitrate (NO3-) and nitrite (NO2-) concentrations under resting and fasting conditions in different type of individuals and their association with blood pressure levels. A total of 77 studies, involving 1918 individuals aged 19-74 years (males = 906; females = 1012), which measured plasma and/or salivary NO3- and NO2- using the chemiluminescence technique, were included. Mean plasma NO3- and NO2- concentrations were 33.9 μmol/L and 158.3 nmol/L, respectively. Subgroup analyses revealed lower plasma NO3- and NO2- concentrations in individuals with cardiometabolic risk (NO3-: 21.2 μmol/L; 95 % CI, 13.4-29.0; NO2-: 122.8 nmol/L; 95 % CI, 75.3-138.9) compared to healthy (NO3-: 33.9 μmol/L; 95 % CI, 29.9-37.9; NO2-: 159.5 nmol/L; 95 % CI, 131.8-187.1; P < 0.01) and trained individuals (NO3-: 43.0 μmol/L; 95 % CI, 13.2-72.9; NO2-: 199.3 nmol/L; 95 % CI, 117.6-281; P < 0.01). Mean salivary NO3- and NO2- concentrations were 546.2 μmol/L and 197.8 μmol/L, respectively. Salivary NO3-, but no NO2-, concentrations were higher in individuals with cardiometabolic risk (680.0 μmol/L; 95 % CI, 510.2-849.8; P = 0.001) compared to healthy individuals (535.9 μmol/L; 95 % CI, 384.2-687.6). A significant positive association (coefficient, 15.4 [95 % CI, 0.255 to 30.5], P = 0.046) was observed between salivary NO3- and diastolic blood pressure (DBP). These findings suggest that the health status is positively associated with plasma NO3- and NO2- concentrations, but the circulatory levels of these anions are not associated with blood pressure. Only salivary NO3- showed a significant positive association with DBP.

Comparison of microbial adhesion and biofilm formation on different orthodontic aligners

INTRODUCTION

This study aimed to compare and evaluate time-dependent biofilm formation and microbial adhesion on 6 different clear aligner systems: Invisalign (Align Technology, San Jose, Calif), Clarity (3M ESPE Maplewood, Minn), ClearCorrect (Institut Straumann AG, Basel, Switzerland), Smartee (Smartee Denti-Technology, Shanghai, China), Orthero (Orthero, Istanbul, Turkey) and Graphy (Graphy Inc, Seoul, South Korea).

METHODS

Streptococcus mutans (ATCC 25175) and Lactobacillus acidophilus (ATCC 4356) were used to evaluate the microbial adhesion and biofilm formation on orthodontic clear aligners at the 0, 24, 48, 72, 96, 120, 168, and 240 hours. Two-way repeated measures analysis of variance (Greenhouse-Geisser) test and post-hoc Bonferroni T2 tests were used for statistical evaluation. The statistical significance level was set at P <0.05.

RESULTS

It was found that more bacterial formation occurred on ClearCorrect than on Smartee at 120, 168, and 240 hours (P <0.05). It was observed more biofilm formation at 168 hours on Graphy than on Smartee (P <0.05). It was found that S mutans + L acidophilus formed more biofilm at 120 and 168 hours on Graphy than on Invisalign (P <0.05).

CONCLUSIONS

Elevated biofilm formation across all materials carries substantial clinical implications. Orthodontists and patients should remain aware of the increased risk of microbial colonization with extended aligner usage.

Alterations of oral microbiota in young children with autism: Unraveling potential biomarkers for early detection

OBJECTIVES

This study investigated the oral microbiota in young children with autism spectrum disorder (ASD) to determine possible alterations in microbial composition and identify potential biomarkers for early detection.

METHODS

Dental plaque samples from 25 children with ASD (aged 3-6 years; M = 4.79, SD = 0.83) and 30 age- and sex-matched typically developing (TD) children were analyzed using 16S rRNA sequencing.

RESULTS

The results showed lower bacterial diversity in children with ASD compared to controls, with distinct microbial compositions in the ASD and TD groups. Six discriminatory species (Microbacterium flavescens, Leptotrichia sp. HMT-212, Prevotella jejuni, Capnocytophaga leadbetteri, Leptotrichia sp. HMT-392, and Porphyromonas sp. HMT-278) were identified in the oral microbiota of ASD children, while five discriminatory species (Fusobacterium nucleatum subsp. polymorphum, Schaalia sp. HMT-180, Leptotrichia sp. HMT-498, Actinomyces gerencseriae, and Campylobacter concisus) were identified in TD controls. A model generated by random forest and leave-one-out cross-validation achieved an accuracy of 0.813. Receiver operating characteristic analysis yielded a sensitivity of 0.778, a specificity of 0.857, and an AUC (area under curve) of 0.937 (95 % CI: 0.82 - 1.00) for differentiating children with and without ASD.

CONCLUSION

The present study has unveiled significant disparities in the oral microbial composition between ASD and TD children.

SIGNIFICANCE

These findings contribute to understanding the microbiome-brain connection in ASD and its implications for early detection and management. Further research is needed to validate these oral bacterial biomarkers and explore their mechanistic association with ASD pathophysiology.

Microbial boundaries in peri-implantitis: a review of pathogen-related advances

In the field of implantology, peri-implantitis is still a common complication of implant failure. Similar to periodontal disease, this kind of pathological condition is characterized by inflammation of the tissues surrounding dental implants or fillings. The sources of infection have been shown to be chronic periodontitis and poor maintenance of the communion. A thorough examination of the intricate components of peri-implantitis was sought in this review in order to identify common characteristics of the disease with regard to bacteria, biofilm formation, host immunological responses, diagnostic tools, and therapeutic treatments. The aim of this study was to provide a detailed overview of the different bacterial species associated with peri-implantitis, a clinical condition similar to periodontitis, characterized by a higher prevalence of staphylococci and enteric bacteria. The study underscores the importance of employing sophisticated diagnostic methods like cone beam computed tomography. It covers a range of therapeutic approaches including surgical and non-surgical techniques as well as strategies stressing host-modification and photodynamic treatment. The study was conducted using pertinent publications from scientific databases, including Scopus, Google Scholar, PubMed, and Web of Science. We searched these databases using the following terms: periodontitis, microbial, dental implants, peri-implantitis, and biofilm formation.

The Hygienic Significance of Microbiota and Probiotics for Human Wellbeing

The human body can be viewed as a combination of ecological niches inhabited by trillions of bacteria, viruses, fungi, and parasites, all united by the microbiota concept. Human health largely depends on the nature of these relationships and how they are built and maintained. However, personal hygiene practices have historically been focused on the wholesale elimination of pathogens and "hygiene-challenging microorganisms" without considering the collateral damage to beneficial and commensal species. The microbiota can vary significantly in terms of the qualitative and quantitative composition both between different people and within one person during life, and the influence of various environmental factors, including age, nutrition, bad habits, genetic factors, physical activity, medication, and hygienic practices, facilitates these changes. Disturbance of the microbiota is a predisposing factor for the development of diseases and also greatly influences the course and severity of potential complications. Therefore, studying the composition of the microbiota of the different body systems and its appropriate correction is an urgent problem in the modern world. The application of personal hygiene products or probiotics must not compromise health through disruption of the healthy microbiota. Where changes in the composition or metabolic functions of the microbiome may occur, they must be carefully evaluated to ensure that essential biological functions are unaffected. As such, the purpose of this review is to consider the microbiota of each of the "ecological niches" of the human body and highlight the importance of the microbiota in maintaining a healthy body as well as the possibility of its modulation through the use of probiotics for the prevention and treatment of certain human diseases.

A pilot study of the relationship between salivary microbial characteristics and endocrine and immune function in patients with burning mouth syndrome

OBJECTIVES

To explore the potential role of oral bacteria in the pathogenesis of burning mouth syndrome (BMS).

MATERIALS AND METHODS

Fifteen patients with BMS and 15 healthy controls were enrolled in this study. The relative abundance and diversity of salivary bacterial strains were analyzed using metagenomic DNA sequencing. The functionality of non-redundant genes was obtained by comparing the mmseqs2 with the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. BMS relating salivary protein markers were detected using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Partial least-squares discriminant analysis (PLS-DA) revealed that the salivary bacterial profiles of the BMS group (mean age: 38.9 ± 2.2 years) differed significantly from those of the control group (mean age: 34.1 ± 2.3 years) in terms of the abundance of dominant phyla, classes, orders, families, genera and species. Functional analysis revealed distinct endocrine and immune functions in the BMS group. The salivary cortisol and α-amylase levels were significantly higher, and salivary interleukn-6 levels were significantly lower in the BMS group than in the control group. Species contribution analysis of endocrine and immune functions revealed that Streptococcus mitis was an important contributor to endocrine and immune functions in the BMS group.

CONCLUSIONS

Salivary dysbiosis related to endocrine and immune functions may be a possible cause of BMS.

CLINICAL RELEVANCE

These findings could assist in the diagnosis and therapy of BMS.

CLINICAL TRIAL NUMBER

Not applicable.

Diversity and Characteristics of the Oral Microbiome Associated with Self-Reported Ancestral/Ethnic Groups

Periodontitis disproportionately affects genetic ancestral/ethnic groups. To characterize the oral microbiome from different genetic ancestral/ethnic groups, we collected 161 dental plaque samples from self-identified African Americans (AAs), Caucasian Americans (CAs), and Hispanic Americans (HAs) with clinical gingival health or biofilm-induced gingivitis on an intact periodontium. DNA was extracted from these samples, and then DNA libraries were prepared and sequenced using an Illumina NovaSeq high-throughput sequencer. We found significant differences in the diversity and abundance of microbial taxa among dental plaque samples of the AA, CA, and HA groups. We also identified unique microbial species in a self-reported ancestral/ethnic group. Moreover, we revealed variations in functional potentials of the oral microbiome among the three ancestral/ethnic groups, with greater diversity and abundance of antibiotic-resistant genes in the oral microbiome and significantly more genes involved in the modification of glycoconjugates and oligo- and polysaccharides in AAs than in CAs and HAs. Our observations suggest that the variations in the oral microbiome associated with ancestral/ethnic backgrounds may directly relate to their virulence potential including their abilities to induce host immune responses and to resist antibiotic treatment. These finding can be a steppingstone for developing precision medicine and personalized periodontal prevention/treatment and for reducing oral health disparities.

Antimicrobial activity of PMMA enriched with nano-clay loaded with metronidazole and chlorhexidine

Poly(methyl methacrylate) (PMMA) materials are highly susceptible to microbial colonization, predisposing patients to oral infections. To address this concern, we loaded PMMA samples with montmorillonite clay (MMT), a crystalline nanoparticle, in combination with chlorhexidine (CHX) or metronidazole (MET) targeting improved antimicrobial action. PMMA samples were prepared with or without MMT loaded with either CHX or MET, establishing the following groups: control (acrylic resin without the addition of nanoparticles), MMT/CHX (acrylic resin with 5% by weight of MMT loaded with CHX), and MMT/MET (acrylic resin with 5% by weight of MMT loaded with MET). Mechanical properties such flexural strength, flexural modulus, and Knoop hardness were evaluated using a universal testing machine. Antimicrobial efficacy was assessed via agar diffusion tests against Enterococcus faecalis and Porphyromonas gingivalis. The addition of MMT loaded with CHX did not affect the flexural strength and flexural modulus of PMMA compared to the control group (p > 0.05). However, MMT/MET reduced all mechanical properties of PMMA (p < 0.05). Both loaded-PMMA materials demonstrated antibacterial activity against E. faecalis but not against P. gingivalis. In conclusion, the incorporation of MMT/CHX into acrylic resin appears to be the most promising approach to combat microbial colonization while preserving PMMA mechanical properties. Future research should focus on optimizing material characteristics to enhance antimicrobial properties, paving the way for clinical applicability.

Exploring links between oral health and infective endocarditis

Infective endocarditis (IE) is a bacterial infection of the heart's inner lining. A low incidence rate combined with a high mortality rate mean that IE can be difficult to treat effectively. There is currently substantial evidence supporting a link between oral health and IE with the oral microbiome impacting various aspects of IE, including pathogenesis, diagnosis, treatment, and mortality rates. The oral microbiome is highly diverse and plays a crucial role in maintaining oral health by providing protective functions. However, when dysbiosis occurs, conditions such as periodontal or peri-implant disease can arise, offering a pathway for bacteraemia to develop. The role of the oral microbiome as a coloniser, facilitator and driver of IE remains to be uncovered by next-generation sequencing techniques. Understanding the dysbiosis and ecology of the oral microbiome of IE patients will allow improvements into the diagnosis, treatment, and prognosis of the disease. Furthermore, an increased awareness amongst those at high-risk of developing IE may encourage improved oral hygiene methods and lower incidence rates. This narrative review examines current findings on the relationship between oral health and IE. It draws from key studies on both topics, with manuscripts selected for their pertinence to the subject. It highlights the link between the oral microbiome and IE by exploring diagnostic techniques and treatments for IE caused by oral commensals.

Dental Pathophysiology of Odontogenic Sinusitis: Periodontitis

Periodontitis is a highly prevalent oral microbial biofilm-driven chronic inflammatory disease. If unmanaged, periodontitis leads to progressive destruction of the ligamentous attachments of teeth to the alveolar bone and resorption of the alveolar bone. It eventually leads to tooth hypermobility and loss. Periodontitis commonly causes overlying maxillary sinus inflammation (mucositis), reflected on radiographic imaging as maxillary sinus mucosal thickening. While uncommon, advanced periodontitis (stage III/IV) or chronic perio-endo lesions can lead to purulent odontogenic sinusitis (ODS). This article describes periodontitis pathophysiology, diagnostic features, and its potential to cause ODS. Clinical practice guideline conform therapy is very successful in managing periodontitis and enabling long-term tooth retention. Localized tooth extration is reserved to end-stage disease.

The oral microbial odyssey influencing chronic metabolic disease

INTRODUCTION

Since the oral cavity is the gateway to the gut, oral microbes likely hold the potential to influence metabolic disease by affecting the gut microbiota.

METHOD

A thorough review of literature has been performed to link the alterations in oral microbiota with chronic metabolic disease by influencing the gut microbiota.

RESULT

A strong correlation exists between abnormalities in oral microbiota and several systemic disorders, such as cardiovascular disease, diabetes, and obesity, which likely initially manifest as oral diseases. Ensuring adequate oral hygiene practices and cultivating diverse oral microflora are crucial for the preservation of general well-being. Oral bacteria have the ability to establish and endure in the gastrointestinal tract, leading to the development of prolonged inflammation and activation of the immune system. Oral microbe-associated prophylactic strategies could be beneficial in mitigating metabolic diseases.

CONCLUSION

Oral microbiota can have a profound impact on the gut microbiota and influence the pathogenesis of metabolic diseases.

Enhanced control of periodontitis by an artificial intelligence-enabled multimodal-sensing toothbrush and targeted mHealth micromessages: A randomized trial

AIM

Treatment of periodontitis, a chronic inflammatory disease driven by biofilm dysbiosis, remains challenging due to patients' poor performance and adherence to the necessary oral hygiene procedures. Novel, artificial intelligence-enabled multimodal-sensing toothbrushes (AI-MST) can guide patients' oral hygiene practices in real-time and transmit valuable data to clinicians, thus enabling effective remote monitoring and guidance. The aim of this trial was to assess the effect of such a system as an adjunct to clinical practice guideline-conform treatment.

MATERIALS AND METHODS

This was a single-centre, double-blind, standard-of-care controlled, randomized, parallel-group, superiority trial. Male and female adults with generalized Stage II/III periodontitis were recruited at the Shanghai Ninth People's Hospital, China. Subjects received a standard-of-care oral hygiene regimen or a technology-enabled, theory-based digital intervention consisting of an AI-MST and targeted doctor's guidance by remote micromessaging. Additionally, both groups received guideline-conform periodontal treatment. The primary outcome was the resolution of inflamed periodontal pockets (≥4 mm with bleeding on probing) at 6 months. The intention-to-treat (ITT) analysis included all subjects who received the allocated treatment and at least one follow-up.

RESULTS

One hundred patients were randomized and treated (50 tests/controls) between 1 February and 30 November 2022. Forty-eight tests (19 females) and 47 controls (16 females) were analysed in the ITT population. At 6 months, the proportion of inflamed periodontal pockets decreased from 80.7% (95% confidence interval [CI] 76.5-84.8) to 52.3% (47.7-57.0) in the control group, and from 81.4% (77.1-85.6) to 44.4% (39.9-48.9) in the test group. The inter-group difference was 7.9% (1.6-14.6, p < .05). Test subjects achieved better levels of oral hygiene (p < .001). No significant adverse events were observed.

CONCLUSIONS

The tested digital health intervention significantly improved the outcome of periodontal therapy by enhancing the adherence and performance of self-performed oral hygiene. The model breaks the traditional model of oral health care and has the potential to improve efficiency and reduce costs (NCT05137392).