Fungi and bacteria occupy distinct spatial niches within carious dentin.

The role of bacteria in the etiology of dental caries is long established, while the role of fungi has only recently gained more attention. The microbial invasion of dentin in advanced caries especially merits additional research. We evaluated the fungal and bacterial community composition and spatial distribution within carious dentin. Amplicon 16S rRNA gene sequencing together with quantitative PCR was used to profile bacterial and fungal species in caries-free children (n = 43) and 4 stages of caries progression from children with severe early childhood caries (n = 32). Additionally, healthy (n = 10) and carious (n = 10) primary teeth were decalcified, sectioned, and stained with Grocott's methenamine silver, periodic acid Schiff (PAS) and calcofluor white (CW) for fungi. Immunolocalization was also performed using antibodies against fungal ß-D-glucan, gram-positive bacterial lipoteichoic acid, gram-negative endotoxin, Streptococcus mutans, and Candida albicans. We also performed field emission scanning electron microscopy (FESEM) to visualize fungi and bacteria within carious dentinal tubules. Bacterial communities observed included a high abundance of S. mutans and the Veillonella parvula group, as expected. There was a higher ratio of fungi to bacteria in dentin-involved lesions compared to less severe lesions with frequent preponderance of C. albicans, C. dubliniensis, and in one case C. tropicalis. Grocott's silver, PAS, CW and immunohistochemistry (IHC) demonstrated the presence of fungi within carious dentinal tubules. Multiplex IHC revealed that fungi, gram-negative, and gram-positive bacteria primarily occupied separate dentinal tubules, with rare instances of colocalization. Similar findings were observed with multiplex immunofluorescence using anti-S. mutans and anti-C. albicans antibodies. Electron microscopy showed monomorphic bacterial and fungal biofilms within distinct dentin tubules. We demonstrate a previously unrecognized phenomenon in which fungi and bacteria occupy distinct spatial niches within carious dentin and seldom co-colonize. The potential significance of this phenomenon in caries progression warrants further exploration.

Small RNA SmsR1 modulates acidogenicity and cariogenic virulence by affecting protein acetylation in Streptococcus mutans.

Post-transcriptional regulation by small RNAs and post-translational modifications (PTM) such as lysine acetylation play fundamental roles in physiological circuits, offering rapid responses to environmental signals with low energy consumption. Yet, the interplay between these regulatory systems remains underexplored. Here, we unveil the cross-talk between sRNAs and lysine acetylation in Streptococcus mutans, a primary cariogenic pathogen known for its potent acidogenic virulence. Through systematic overexpression of sRNAs in S. mutans, we identified sRNA SmsR1 as a critical player in modulating acidogenicity, a key cariogenic virulence feature in S. mutans. Furthermore, combined with the analysis of predicted target mRNA and transcriptome results, potential target genes were identified and experimentally verified. A direct interaction between SmsR1 and 5'-UTR region of pdhC gene was determined by in vitro binding assays. Importantly, we found that overexpression of SmsR1 reduced the expression of pdhC mRNA and increased the intracellular concentration of acetyl-CoA, resulting in global changes in protein acetylation levels. This was verified by acetyl-proteomics in S. mutans, along with an increase in acetylation level and decreased activity of LDH. Our study unravels a novel regulatory paradigm where sRNA bridges post-transcriptional regulation with post-translational modification, underscoring bacterial adeptness in fine-tuning responses to environmental stress.

Portable Saliva Sensor Based on Dual Recognition Elements for Detection of Caries Pathogenic Bacteria.

Dental caries is one of the most common diseases affecting more than 2 billion people's health worldwide. In a clinical setting, it is challenging to predict and proactively guard against dental cavities prior to receiving a confirmed diagnosis. Streptococcus mutans (S. mutans) in saliva has been recognized as the main causative bacterial agent that causes dental caries. High sensitivity, good selectivity, and a wide detection range are incredibly important factors to affect S. mutans detection in practical applications. In this study, we present a portable saliva biosensor designed for the early detection of S. mutans with the potential to predict the occurrence of dental cavities. The biosensor was fabricated using a S. mutans-specific DNA aptamer and S. mutans-imprinted polymers. Methylene blue was utilized as a redox probe in the sensor to generate current signals for analysis. When S. mutans enters complementarily S. mutans cavities, it blocks electron transfer between methylene blue and the electrode, resulting in decreases in the reduction current signal. The signal variations are associated with S. mutans concentrations that are useful for quantitative analysis. The linear detection range of S. mutans is 102-109 cfu mL-1, which covers the critical concentration of high caries risk. The biosensor exhibited excellent selectivity toward S. mutans in the presence of other common oral bacteria. The biosensor's wide detection range, excellent selectivity, and low limit of detection (2.6 cfu mL-1) are attributed to the synergistic effect of aptamer and S. mutans-imprinted polymers. The sensor demonstrates the potential to prevent dental caries.

Metabolomics reveals high fructose-1,6-bisphosphate from fluoride-resistant Streptococcus mutans.

BACKGROUND: Fluoride-resistant Streptococcus mutans (S. mutans) strains have developed due to the wide use of fluoride in dental caries prevention. However, the metabolomics of fluoride-resistant S. mutans remains unclear. OBJECTIVE: This study aimed to identify metabolites that discriminate fluoride-resistant from wild-type S. mutans. MATERIALS AND METHODS: Cell supernatants from fluoride-resistant and wild-type S. mutans were collected and analyzed by liquid chromatography-mass spectrometry. Principal components analysis and partial least-squares discriminant analysis were performed for the statistical analysis by variable influence on projection (VIP > 2.0) and p value (Mann-Whitney test, p < 0.05). Metabolites were assessed qualitatively using the Human Metabolome Database version 2.0 ( http://www.hmdb.ca ), or Kyoto Encyclopedia of Genes and Genomes ( http://www.kegg.jp ), and Metaboanalyst 6.0 ( https://www.metaboanalyst.ca ). RESULTS: Fourteen metabolites differed significantly between fluoride-resistant and wild-type strains in the early log phase. Among these metabolites, 5 were identified. There were 32 differential metabolites between the two strains in the stationary phase, 13 of which were identified. The pyrimidine metabolism for S. mutans FR was matched with the metabolic pathway. CONCLUSIONS: The fructose-1,6-bisphosphate concentration increased in fluoride-resistant strains under acidic conditions, suggesting enhanced acidogenicity and acid tolerance. This metabolite may be a promising target for elucidating the cariogenic and fluoride resistant mechanisms of S. mutans.

Periodontal inflammatory and microbial profiles in healthy young African Americans and Caucasians.

AIM: This study aimed to compare microbial and inflammatory profiles in periodontally/systemically healthy African American (AA) and Caucasian (C) individuals. MATERIALS AND METHODS: Thirty-seven C and 46 AA aged from 5 to 25 years were evaluated regarding periodontal disease, caries, microbial subgingival profile via 16-s sequencing, as well as salivary and gingival crevicular fluid (GCF) inflammatory profile via multiplex assay. RESULTS: Greater probing depth percentage was detected in AA (p = .0075), while a higher percentage of caries index (p = .0069) and decayed, missing, filled teeth (DMFT) index (p = .0089) was observed in C, after adjusting for number of teeth, sex and age. Salivary levels of IL-6, IL-8 and TNFα were higher for C, whereas GCF levels of eotaxin, IL-12p40, IL-12p70, IL-2 and MIP-1α were higher in AA (p < .05). Different microbial profiles were observed between the races (p = .02). AA presented higher abundance of periodontopathogens (such as Tanerella forsythia, Treponema denticola, Filifactor alocis, among others), and C presented more caries-associated bacteria (such as Streptococcus mutans and Prevotella species). Bacillaceae and Lactobacillus species were associated with higher DMFT index, whereas Fusobacterium and Tanerella species with periodontal disease parameters. CONCLUSIONS: A different inflammatory and bacterial profile was observed between healthy AA and C, which may predispose these races to higher susceptibility to specific oral diseases.

Association of Root Biofilm Bacteriome with Root Caries Lesion Severity and Activity.

INTRODUCTION: This research aimed to assess the association of root biofilm bacteriome with root caries lesion severity and activity in institutionalised Colombian elderlies and was conducted to gather data on the root caries bacteriome in this population. METHODS: A bacteriome evaluation of biofilm samples from sound and carious root surfaces was performed. Root caries was categorised (ICDAS Root criteria) based on severity (sound surfaces, initial: non-cavitated, moderate/extensive combined: cavitated) and activity status (active and inactive). DNA was extracted and the V4 region of the 16S rRNA gene was sequenced; afterwards the classification of features was conducted employing amplicon sequence variants and taxonomic assignment via the Human Oral Microbiome Database (HOMD). Bacterial richness, diversity (Simpson's and Shannon's indices), and relative abundance estimation were assessed and compared based on root caries severity and activity status (including Sound surfaces). RESULTS: A total of 130 biofilm samples were examined: sound (n = 45) and with root caries lesions (n = 85; by severity: initial: n = 41; moderate/extensive: n = 44; by activity: active: n = 60; inactive: n = 25). Species richness was significantly lower in biofilms from moderate/extensive and active groups compared to sound sites. There was a higher relative abundance of species like Lechtotricia wadei, Capnocytophaga granulosa, Cardiobacterium valvarum, Porphyromonas pasteri - in sound sites; Dialister invisus, Streptococcus mutans, Pseudoramibacter alactolyticus and Bacteroidetes (G-5) bacterium 511 - in moderate/extensive lesions, and Fusobacterium nucleatum subsp. animalis, Prevotella denticola, Lactobacillus fermentum, Saccharibacteria (TM7) (G-5)bacterium HMT 356 - in active lesions. CONCLUSION: Root caries bacteriome exhibited differences in species proportions between the compared groups. Specifically, cavitated caries lesions and active caries lesions showed higher relative abundance of acidogenic bacteria.

An in vitro coculture approach to study the interplay between dental pulp cells and Streptococcus mutans.

AIM: To develop a new coculture system that allows exposure of dental pulp cells (DPCs) to Streptococcus mutans and dentine matrix proteins (eDMP) to study cellular interactions in dentine caries. METHODOLOGY: Dental pulp cells and S. mutans were cocultured with or without eDMP for 72 h. Cell proliferation and viability were assessed by cell counting and MTT assays, while bacterial growth and viability were determined by CFU and LIVE/DEAD staining. Glucose catabolism and lactate excretion were measured photometrically as metabolic indicators. To evaluate the inflammatory response, the release of cytokines and growth factors (IL-6, IL-8, TGF-ß1, VEGF) was determined by ELISA. Non-parametric statistical analyses were performed to compare all groups and time points (Mann-Whitney U test or Kruskal-Wallis test; α = .05). RESULTS: While eDMP and especially S. mutans reduced the number and viability of DPCs (p ≤ .0462), neither DPCs nor eDMP affected the growth and viability of S. mutans during coculture (p > .0546). The growth of S. mutans followed a common curve, but the death phase was not reached within 72 h. S. mutans consumed medium glucose in only 30 h, whereas in the absence of S. mutans, cells were able to catabolize glucose throughout 72 h, resulting in the corresponding amount of l-lactate. No change in medium pH was observed. S. mutans induced IL-6 production in DPCs (p ≤ .0011), whereas eDMP had no discernible effect (p > .7509). No significant changes in IL-8 were observed (p > .198). TGF-ß1, available from eDMP supplementation, was reduced by DPCs over time. VEGF, on the other hand, was increased in all groups during coculture. CONCLUSIONS: The results show that the coculture of DPCs and S. mutans is possible without functional impairment. The bacterially induced stimulation of proinflammatory and regenerative cytokines provides a basis for future investigations and the elucidation of molecular biological relationships in pulp defence against caries.

Clinical characteristics and caries risk assessment of tobacco heating systems smokers, cigarette smokers and non-smokers: a cross-sectional study.

OBJECTIVES: The study compared clinical characteristics and caries risk assessments between tobacco heating system (THS) smokers, cigarette smokers and non-smokers. MATERIALS AND METHODS: General data, data regarding fluoridation, smoking and dietary habits was obtained through a questionnaire. Caries experience was assessed by the DMFT index; the amount of biofilm by the Full mouth plaque score index; the amount of salivation by the quantum of stimulated salivation test; salivary pH with pH indicator strips and salivary number of S.mutans and Lactobacilli by cultivation on agar plates. The Cariogram method was used to assess caries risk. RESULTS: No differences between the groups was detected regarding education level, average daily number of meals, fluoridation programs, systemic diseases, and caries experience. The groups significantly differed in the amount of salivary S.mutans and Lactobacilli (p < 0.001), accumulated biofilm (p = 0.034), salivation quantum (p < 0.001), and saliva pH (p = 0.009). Exposure to tobacco smoke and heated tobacco aerosol increased the accumulation of biofilm and decreased salivary pH. Smoking increased S. mutans, while THS consumption decreased salivation and Lactobacilli the most. The Cariogram analysis found no differences in chances of avoiding new caries lesions between the groups, but a significant difference in developing caries lesions due to dietary habits was detected (p < 0.001) with non-smokers having higher risk than smokers, but not than THS consumers. CONCLUSIONS: THS and cigarette smoking were related to clinical characteristics that affect caries activity even though the caries risk assessment revealed no significant difference in the chances of avoiding new caries lesions between the groups. CLINICAL RELEVANCE: THS and cigarette smokers could have higher caries activity than non-smokers. The clinical study protocol has been registered on ClinicalTrials.gov under the ID number: NCT06314100.

The effect of nano silver fluoride, self-assembling peptide and sodium fluoride varnish on salivary cariogenic bacteria: a randomized controlled clinical trial.

OBJECTIVES: To compare the antibacterial effect of Nanosilver Fluoride varnish (NSF) varnish, P11-4 and Sodium Fluoride (NaF) varnish against salivary Streptococcus mutans (S. mutans) and Lactobacilli. METHODS: 66 patients aged 10-24 years old were randomly assigned to receive single application of NSF, P11-4 or NaF varnish. Baseline unstimulated saliva samples were collected before the agents were applied and S.mutans and Lactobacilli colony forming units (CFU) were counted. After one, three and six months, microbiological samples were re-assessed. Groups were compared at each time point and changes across time were assessed. Multivariable linear regression compared the effect of P11-4 and NSF to NaF on salivary S. mutans and Lactobacilli log count at various follow up periods. RESULTS: There was a significant difference in salivary S. mutans log count after 1 month between P11-4 (B= -1.29, p = 0.049) and NaF but not at other time points nor between NSF and NaF at any time point. The significant reduction in bacterial counts lasted up to one month in all groups, to three months after using P11-4 and NaF and returned to baseline values after six months. CONCLUSION: In general, the antimicrobial effect of P11-4 and NSF on salivary S. mutans and Lactobacilli was not significantly different from NaF varnish. P11-4 induced greater reduction more quickly than the two other agents and NSF antibacterial effect was lost after one month. CLINICAL RELEVANCE: NSF varnish and P11-4 have antimicrobial activity that does not significantly differ from NaF by 3 months. P11-4 has the greatest antibacterial effect after one month with sustained effect till 3 months. The antibacterial effect of NSF lasts for one month. NaF remains effective till 3 months. TRIAL REGISTRATION: This trial was prospectively registered on the clinicaltrials.gov registry with ID: NCT04929509 on 18/6/2021.

The effect of bovine trypsin on dental biofilm dispersion: an in vitro study.

To investigate the degradation effect of bovine trypsin on multispecies biofilm of caries-related bacteria and provide an experimental foundation for the prevention of dental caries. Standard strains of S. mutans, S. sanguis, S. gordonii, and L. acidophilus were co-cultured to form 24 h, 48 h, and 72 h biofilms. The experimental groups were treated with bovine trypsin for 30 s, 1 min, and 3 min. Morphological observation and quantitative analysis of extracellular polymeric substances (EPS), live bacteria, and dead bacteria were conducted using the confocal laser scanning microscope (CLSM). The morphological changes of EPS and bacteria were also observed using a scanning electron microscope (SEM). When biofilm was treated for 1 min, the minimal inhibitory concentration (MIC) of bovine trypsin to reduce EPS was 0.5 mg/mL in 24 h and 48 h biofilms, and the MIC of bovine trypsin was 2.5 mg/mL in 72 h biofilms (P < 0.05). When biofilm was treated for 3 min, the MIC of bovine trypsin to reduce EPS was 0.25 mg/mL in 24 h and 48 h biofilms, the MIC of bovine trypsin was 1 mg/mL in 72 h biofilm (P < 0.05). The ratio of live-to-dead bacteria in the treatment group was significantly lower than blank group in 24 h, 48 h, and 72 h multispecies biofilms (P < 0.05). Bovine trypsin can destroy multispecies biofilm structure, disperse biofilm and bacteria flora, and reduce the EPS and bacterial biomass in vitro, which are positively correlated with the application time and concentration.

SepM mutation in Streptococcus mutans clinical isolates and related function analysis.

BACKGROUND: Streptococcus mutans (S. mutans) is an important pathogenic bacterium that causes dental caries, while Streptococcus gordonii (S. gordonii) is a non-cariogenic bacterium that inhibits the growth of S. mutans. The SepM protein can promote the inhibitory ability of S. mutans against S. gordonii by cleaving CSP-21 and activating the ComDE two-component system. This study was designed to explore sepM mutation in S. mutans clinical isolates and related function in the regulation of interactions with S. gordonii. METHODS: The S. mutans clinical strains that can inhibit the growth of S. gordonii constitute the inhibitory group. 286 C-serotype S. mutans strains were categorized into S. gordonii inhibitory (n = 114) and non-inhibitory bacteria (n = 172). We detected sanger sequencing of sepM gene, the expression levels of related genes and proteins in clinical isolates, obtained prokaryotic expression and purification of mutated proteins, and analyzed the effect of the target mutations on the binding between SepM and CSP-21. RESULTS: We found that C482T, G533A, and G661A missense mutations were presented at significantly higher frequency in the inhibitory group relative to the non-inhibitory group. There was no significant difference in the expression of the sepM gene between selected clinical isolates harboring the G533A mutation and the control group. The expression levels of SepM, phosphorylated ComD, and ComE in the mutation group were significantly higher than those in the control group. SepM_control and SepM_D221N (G661A at the gene level) were found to contain two residues close to the active center while SepM_G178D (G533A at the gene level) contained three residues close to the active center. At 25 °C and a pH of 5.5, SepM_D221N (G661A) exhibited higher affinity for CSP-21 (KD = 8.25 µM) than did the SepM control (KD = 33.1 µM), and at 25 °C and a pH of 7.5, SepM_G178D (G533A) exhibited higher affinity (KD = 3.02 µM) than the SepM control (KD = 15.9 µM). It means that it is pH dependent. CONCLUSIONS: Our data suggest that increased cleavage of CSP-21 by the the mutant SepM may be a reason for the higher inhibitory effect of S. mutans on S. gordonii .

Unlocking the potential of probiotic administration in caries management: a systematic review.

BACKGROUND: The use of prebiotics and/or probiotic bacteria with the potential to modulate the oral ecosystem may play an important role in the prevention and management of dental caries. To assess the evidence of the potential of pre/probiotics both in the prevention and treatment of dental caries, we focused on the PICO question "In individuals with caries, after probiotic administration, is there an improvement in outcomes directly related to caries risk and development?". METHODS: An extensive systematic search was conducted in electronic databases PubMed, Web of Science, Scopus and Cochrane, to identify articles with relevant data. This systematic review included trials performed in Humans; published in English; including the observation of patients with caries, with clear indication of the probiotic used and measuring the outcomes directly involved with the cariogenic process, including the quantification of bacteria with cariogenic potential. To evaluate the methodological quality of the studies, the critical assessment tool from the Joanna Briggs Institute was used. RESULTS: Eight hundred and fifty articles, potentially relevant, were identified. Following PRISMA guidelines 14 articles were included in this systematic review. Outcomes such as reduction of cariogenic microorganism counts, salivary pH, buffer capacity, and caries activity were assessed. The probiotic most often referred with beneficial results in dental caries outcomes is Lacticaseibacillus rhamnosus. Regarding the most used administration vehicle, in studies with positive effects on the caries management, probiotic supplemented milk could be considered the best administration vehicle. CONCLUSIONS: Evidence suggests a beneficial effect of probiotic supplemented milk (Lacticaseibacillus rhamnosus) as an adjuvant for caries prevention and management. However, comparable evidence is scarce and better designed and comparable studies are needed.

A comparative study of microbial changes in dental plaque before and after single- and multiappointment treatments in patients with severe early childhood caries.

BACKGROUND: The status of dental caries is closely related to changes in the oral microbiome. In this study, we compared the diversity and structure of the dental plaque microbiome in children with severe early childhood caries (S-ECC) before and after general anaesthesia and outpatient treatment. METHODS: Forty children aged 3 to 5 years with S-ECC who had completed whole-mouth dental treatment under general anaesthesia (C1) or in outpatient settings (C2) were selected, 20 in each group. The basic information and oral health status of the children were recorded, and the microbial community structure and diversity of dental plaque before treatment (C1, C2), the day after treatment(C2_0D), 7 days after treatment (C1_7D, C2_7D), 1 month after treatment (C1_1M, C2_1M), and 3 months after treatment (C1_3M, C2_3M) were analysed via 16 S rRNA high-throughput sequencing technology. RESULTS: (1) The alpha diversity test showed that the flora richness in the multiappointment group was significantly greater at posttreatment than at pretreatment (P < 0.05), and the remaining alpha diversity index did not significantly differ between the 2 groups (P > 0.05). The beta diversity analysis revealed that the flora structures of the C1_7D group and the C2_3M group were significantly different from those of the other time points within the respective groups (P < 0.05). (2) The core flora existed in both the pre- and posttreatment groups, and the proportion of their flora abundance could be altered depending on the caries status of the children in both groups. Leptotrichia abundance was significantly (P < 0.05) lower at 7 days posttreatment in both the single- and multiappointment groups. Corynebacterium and Corynebacterium_matruchotii were significantly more abundant in the C1_1M and C1_3M groups than in the C1 and C1_7D groups (P < 0.05). Streptococcus, Haemophilus and Haemophilus_parainfluenzae were significantly more abundant in the C1_7D group than in the other groups (P < 0.05). CONCLUSION: A single session of treatment under general anaesthesia can cause dramatic changes in the microbial community structure and composition within 7 days after treatment, whereas treatment over multiple appointments may cause slow changes in oral flora diversity.

Effects of Sjogren's syndrome and high sugar diet on oral microbiome in patients with rampant caries: a clinical study.

OBJECTIVE: The purpose of this study was to assess the composition of the oral microbial flora of adults with rampant caries in China to provide guidance for treatment. PATIENTS AND METHODS: Sixty human salivary and supragingival plaque samples were collected. They were characterized into four groups: patients with rampant caries with Sjogren's syndrome (RC-SS) or high-sugar diet (RC-HD), common dental caries (DC), and healthy individuals (HP). The 16S rRNA V3-V4 region of the bacterial DNA was detected by Illumina sequencing. PCoA based on OTU with Bray-Curtis algorithm, the abundance of each level, LEfSe analysis, network analysis, and PICRUSt analysis were carried out between the four groups and two sample types. Clinical and demographic data were compared using analysis of variance (ANOVA) or the nonparametric Kruskal-Wallis rank-sum test, depending on the normality of the data, using GraphPad Prism 8 (P < 0.05). RESULTS: OTU principal component analysis revealed a significant difference between healthy individuals and those with RC-SS. In the saliva of patients with rampant caries, the relative abundance of Firmicutes increased significantly at the phylum level. Further, Streptocpccus, Veillonella, Prevotella, and Dialister increased, while Neisseria and Haemophilus decreased at the genus level. Veillonella increased in the plaque samples of patients with rampant caries. CONCLUSION: Both salivary and dental plaque composition were significantly different between healthy individuals and patients with rampant caries. This study provides a microbiological basis for exploring the etiology of rampant caries. CLINICAL RELEVANCE: This study provides basic information on the flora of the oral cavity in adults with rampant caries in China. These findings could serve as a reference for the treatment of this disease.

Alterations and correlations in dental plaque microbial communities and metabolome characteristics in patients with caries, periodontitis, and comorbid diseases.

BACKGROUNDS: The pathogenic microorganisms and clinical manifestations of caries and periodontitis are different, caries and periodontitis are usually discussed separately, and the relationship between them is ignored. Clinically, patients prone to dental caries generally have a healthier periodontal status, whereas patients with periodontitis generally have a lower incidence of dental caries. The relationship between dental caries and periodontitis remains unclear. OBJECTIVES: This study aimed to explain the clinical phenomenon of antagonism between dental caries and periodontitis by exploring the ecological chain and bacterial interactions in dental caries, periodontitis, and other comorbid diseases. METHODS: The dental plaque microbiomes of 30 patients with oral diseases (10 each with caries, periodontitis, and comorbid diseases) were sequenced and analysed using 16 S rRNA gene sequencing. The Kyoto Encyclopaedia of Genes and Genomes (KEGG) database was used for a differential functional analysis of dental plaque microbial communities in caries, periodontitis, and comorbid diseases. RESULTS: The coinfection group had the greatest bacterial richness in dental plaque. The principal coordinate analysis showed that caries and periodontitis were separate from each other, and comorbid diseases were located at the overlap of caries and periodontitis, with most of them being periodontitis. Simultaneously, we compared the microbiomes with significant differences among the three groups and the correlations between the microbiome samples. In addition, KEGG pathway analysis revealed significant differences in functional changes among the three groups. CONCLUSIONS: This study revealed the composition of the dental plaque microbial communities in caries, periodontitis, and comorbidities and the differences among the three. Additionally, we identified a possible antagonism between periodontitis and caries. We identified a new treatment strategy for the prediction and diagnosis of caries and periodontitis.

Assessment of oral bacteria potentially associated with the mobile microbiome in children with congenital heart disease.

In this case-control study, we aimed to investigate the specific oral pathogens potentially associated with the mobile microbiome in children with congenital heart disease (CHD). Caries, oral hygiene and gingival indices were evaluated in 20 children with CHD and a healthy control group, and venous blood samples and saliva were collected. Using quantitative polymerase chain reaction (qPCR), blood samples were analyzed for the presence of bacterial DNA to determine the mobile microbiome, and saliva samples were analyzed to identify and quantify target microorganisms, including Streptococcus mutans (Sm) and its serotype k (Smk), Fusobacterium. nucleatum (Fn), Porphyromonas gingivalis (Pg), Scardovia wiggsiae (Sw) and Aggregitibacter actinomycetemcomitans (Aa) and its JP2 clone (JP2). The findings were analyzed by Mann Whitney U, chi-square, Fisher's exact and Spearman's Correlation tests. Bacterial DNA was identified in two blood samples. No significant differences were found between the groups regarding the presence and counts of bacteria in saliva. However, the CHD group exhibited significantly lower caries and higher gingival index scores than the control group. The presence of Pg and Aa were significantly associated with higher gingival index scores. Sm and Smk counts were significantly correlated with caries experience. A positive correlation was found between Fn and total bacteria counts. In conclusion, the mobile microbiome, which has been proposed as a potential marker of dysbiosis at distant sites, was very rare in our pediatric population. The counts of target microorganisms which are potentially associated with the mobile microbiome did not differ in children with CHD and healthy children.

Mutanofactin promotes adhesion and biofilm formation of cariogenic Streptococcus mutans.

Cariogenic Streptococcus mutans is known as a predominant etiological agent of dental caries due to its exceptional capacity to form biofilms. From strains of S. mutans isolated from dental plaque, we discovered, in the present study, a polyketide/nonribosomal peptide biosynthetic gene cluster, muf, which directly correlates with a strong biofilm-forming capability. We then identified the muf-associated bioactive product, mutanofactin-697, which contains a new molecular scaffold, along with its biosynthetic logic. Further mode-of-action studies revealed that mutanofactin-697 binds to S. mutans cells and also extracellular DNA, increases bacterial hydrophobicity, and promotes bacterial adhesion and subsequent biofilm formation. Our findings provided an example of a microbial secondary metabolite promoting biofilm formation via a physicochemical approach, highlighting the importance of secondary metabolism in mediating critical processes related to the development of dental caries.

Spatial mapping of polymicrobial communities reveals a precise biogeography associated with human dental caries.

Tooth decay (dental caries) is a widespread human disease caused by microbial biofilms. Streptococcus mutans, a biofilm-former, has been consistently associated with severe childhood caries; however, how this bacterium is spatially organized with other microorganisms in the oral cavity to promote disease remains unknown. Using intact biofilms formed on teeth of toddlers affected by caries, we discovered a unique 3D rotund-shaped architecture composed of multiple species precisely arranged in a corona-like structure with an inner core of S. mutans encompassed by outer layers of other bacteria. This architecture creates localized regions of acidic pH and acute enamel demineralization (caries) in a mixed-species biofilm model on human teeth, suggesting this highly ordered community as the causative agent. Notably, the construction of this architecture was found to be an active process initiated by production of an extracellular scaffold by S. mutans that assembles the corona cell arrangement, encapsulating the pathogen core. In addition, this spatial patterning creates a protective barrier against antimicrobials while increasing bacterial acid fitness associated with the disease-causing state. Our data reveal a precise biogeography in a polymicrobial community associated with human caries that can modulate the pathogen positioning and virulence potential in situ, indicating that micron-scale spatial structure of the microbiome may mediate the function and outcome of host-pathogen interactions.

Salivary microbiome diversity in Chinese children with various caries states.

OBJECTIVE: This study aimed to explore oral microbiome diversity among children with various caries status based on dmft scores. METHODS: A total of 320 children aged 3-5 years were recruited, with 66 healthy children and 254 children affected by dental caries. According to dmft scores, these children with dental caries were classified as "mild group" (dmft score 1-3), "moderate group" (dmft score 4-6), and "severe group" (dmft score 7-14). Healthy children with dmft score of 0 served as control group. Illumina MiSeq sequencing was employed to analyze all salivary samples collected from these children. RESULTS: The salivary microbial diversity among four groups was similar (p > 0.05). A total of five bacterial genera were highly abundant in the control group including Bergeyella, Acidimicrobiales, Acidimicrobiia, Halomonas, and Blautia (p < 0.05). For mild group, there were nine bacterial genera identified to be predominant: Porphyromonadaceae, Porphyromonas, Enterobacteriales, Enterobacteriaceae, Weissella, Leuconostocaceae, Alphaproteobacteria, Stenotrophomonas, and Rhizobiales (p < 0.05). Only one genus, Aggregatibacter was predominant in moderate group (p < 0.05). There were six bacterial genera (Alistipes, Lachnoclostridium, Escherichia-Shigella, Romboutsia, Sphingomonadales, and Denitratisoma) enriched in severe group (p < 0.05). CONCLUSION: Oral microbial profile was different in children with various caries status based on dmft scores. CLINICAL RELEVANCE: The results might be beneficial to deeply understand microbiological diversity of early childhood caries (ECC) at various stages and inform effective strategies for ECC prevention.

Bypass gastroplasty impacts oral health, salivary inflammatory biomarkers, and microbiota: a controlled study.

OBJECTIVES: Knowledge about the impact of gastroplasty on oral health and salivary biomarkers is limited. The aim was to prospectively evaluate oral health status, salivary inflammatory markers, and microbiota in patients undergoing gastroplasty compared with a control group undergoing a dietary program. MATERIALS AND METHODS: Forty participants with obesity class II/III were included (20 individuals in each sex-matched group; 23-44 years). Dental status, salivary flow, buffering capacity, inflammatory cytokines, and uric acid were assessed. Salivary microbiological analysis (16S-rRNA sequencing) assessed the abundance of genus, species, and alpha diversity. Cluster analysis and mixed-model ANOVA were applied. RESULTS: Oral health status, waist-to-hip ratio, and salivary alpha diversity were associated at baseline. A subtle improvement in food consumption markers was observed, although caries activity increased in both groups, and the gastroplasty group showed worse periodontal status after three months. IFNγ and IL10 levels decreased in the gastroplasty group at 3 months, while a decrease was observed in the control group at 6 months; IL6 decreased in both groups (p < 0.001). Salivary flow and buffering capacity did not change. Significant changes in Prevotella nigrescens and Porphyromonas endodontalis abundance were observed in both groups, while alpha diversity (Sobs, Chao1, Ace, Shannon, and Simpson) increased in the gastroplasty group. CONCLUSIONS: Both interventions changed in different degrees the salivary inflammatory biomarkers and microbiota, but did not improve the periodontal status after 6 months. CLINICAL RELEVANCE: Although the observed discrete improvement in dietary habits, caries activity increased with no clinical improvement in the periodontal status, emphasizing the need of oral health monitoring during obesity treatment.