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The prevalence of dental caries remains high, posing a major burden on the public health of the global society. Microorganisms are the main cause of dental caries, among which Streptococcus mutans ( S. mutans ) is one of the most widely recognized cariogenic bacteria. In recent years, the progress in research technology enabled the academic circle to conduct more in-depth research into caries-inducing S. mutans at the DNA, RNA and protein levels, and to gain thereby a new understanding of the surface structure and extracellular matrix composition of S. mutans . In this paper, we summarized recent findings on the cariogenic mechanism of S. mutans in order to help reveal more targets and potential approaches for the future development of caries prevention agents that target S. mutans , and to promote the development of dental caries prevention campaign., (Copyright© by Editorial Board of Journal of Sichuan University (Medical Sciences).)

Caries is a chronic infectious disease that occurs in the hard tissues of teeth. The interaction of oral microorganisms, host, food and time leads to the occurrence and progression of caries. Free sugar is an important food factor in the occurrence of dental caries. This paper reviews the research progress on the relationship between free sugar and caries in recent years, providing a reference for further clarifying the mechanism of the occurrence and progression of caries caused by free sugar and exploring the methods of caries prevention. The cariogenic mechanism of free sugar is multifaceted. Free sugar can not only be used by oral microorganisms in dental plaque biofilms to produce acid and synthesize intracellular and extracellular polysaccharides but also cause an imbalance in oral microecology and enhance gene expression related to the cariogenic toxicity of oral microorganisms. Based on the correlation between free sugar and caries, it is important to limit the intake amount and frequency of free sugar to prevent caries. This can be achieved mainly by formulating public health policies for reducing sugar, creating a low-sugar family environment with good eating habits, using sugar substitutes and using fluoride. There are few studies on the relationship between free sugar and oral microecology. More research is needed to better understand the effect of free sugar on oral microecology and its mechanism and to validate the caries-preventing effect of various sugar reduction measures. We believe such studies would open up new avenues for the effective prevention of caries.

The oral microecological balance is closely associated with the development of dental caries. Oxidative stress is one of the important factors regulating the composition and structure of the oral microbial community. Streptococcus mutans is closely related to the occurrence and development of dental caries. The ability of S. mutans to withstand oxidative stress affects its survival competitiveness in biofilms. The oxidative stress regulatory mechanisms of S. mutans include the synthesis of reductase, the regulation of iron and manganese uptake by metalloregulatory proteins, transcription regulator Spx, extracellular uptake of glutathione and other related signal transduction systems. The current research focuses on how S. mutans adapts to a complex external environment through an oxidative stress response and its influence on oral microecology. We can design targeted small molecular compounds for key signaling pathways to inhibit oxidative stress and weaken the virulence of S. mutans, which is important for oral microecological modulation and dental caries prevention and treatment.

Streptococcus mutans is the major etiological agent of dental caries in humans. S. mutans overgrowth within dental biofilms can trigger biofilm dysbiosis, ultimately leading to the initiation or progression of dental caries. Polyketides and nonribosomal peptides (PKs/NRPs) are secondary metabolites with complex structures encoded by a cluster of biosynthetic genes. Although not essential for microbial growth, PKs/NRPs play important roles in physiological regulation. Three main classes of hybrid PKs/NRPs in S. mutans have been identified, including mutanobactin, mutanocyclin, and mutanofactin, encoded by the mub, muc, and muf gene clusters, respectively. These three hybrid PKs/NRPs play important roles in environmental adaptation, biofilm formation, and interspecies competition of S. mutans. In this review, we provide an overview of the major hybrid PKs/NRPs of S. mutans, including mutanobactin, mutanocyclin, and mutanofactin and address their ecological roles in dental biofilms. We place specific emphasis on important questions that are yet to be answered to provide novel insights into the cariogenic mechanism of S. mutans and facilitate improved management of dental caries. We highlight that S. mutans PKs/NRPs may be potential novel targets for the prevention and treatment of S. mutans‐induced dental caries. The development of genomics, metabolomics, and mass spectrometry, together with the integration of various databases and bioinformatics tools, will allow the identification and synthesis of other secondary metabolites. Elucidating their physicochemical properties and their ecological roles in oral biofilms is crucial in the identification of novel targets for the ecological management of dental caries. [ABSTRACT FROM AUTHOR]

Oral microecological balance is closely associated with the development of dental caries. Oxidative stress is one of the important factors regulating the composition and structure of the oral microbial community. Streptococcus mutans is linked to the occurrence and development of dental caries. The ability of S. mutans to withstand oxidative stress affects its survival competitiveness in biofilms. The oxidative stress regulatory mechanisms of S. mutans include synthesis of reductase, regulation of metal ions uptake, regulator PerR, transcription regulator Spx, extracellular uptake of glutathione, and other related signal transduction systems. Here, we provide an overview of how S. mutans adapts to oxidative stress and its influence on oral microecology, which may offer novel options to investigate the cariogenic mechanisms of S. mutans in the oral microenvironment, and new targets for the ecological prevention and treatment of dental caries. [ABSTRACT FROM AUTHOR]

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As one of the most common oral diseases in kids, early childhood caries affects the health of children throughout the world. Clinical investigations show the copresence of Candida albicans and Streptococcus mutans in ECC lesions, and mechanistic studies reveal co-existence of C. albicans and S. mutans affects both of their cariogenicity. Clearly a comprehensive understanding of the interkingdom interaction between these two microorganisms has important implications for ECC treatment and prevention. To this end, this review summarizes advances in our understanding of the virulence of both C. albicans and S. mutans. More importantly, the synergistic and antagonistic interactions between these two microbes are discussed. [ABSTRACT FROM AUTHOR]

Biofilm formation under cariogenic conditions contributes to dental caries development, in which Streptococcus mutans (S. mutans) is regarded as the major cariogenic bacteria. Here, we synthesized a series of imidazolium salts. Their properties of antimicrobial and anti-biofilm were investigated. The microdilution method crystal violet staining, and cell counting Kit-8 assay were used to screen imidazolium salts. Then, the bacterial composition in multi-species biofilm composed of S. mutans, Actinomyces naeslundii, and Streptococcus gordonii was quantified by quantitative PCR. The exopolysaccharide and morphology of the structure of multi-species biofilm were further observed by confocal laser scanning microscopy and scanning electron microscope, respectively. Imidazolium salts exhibited highly antimicrobial activity against oral pathogens, especially for S. mutans. Compounds with ortho-diisopropyl and para-methoxyl on N-moieties as well as bearing ancenaphthyl skeleton (C5) showed the lowest cytotoxicity and most efficient anti-biofilm activity. C5 inhibited approximately 50% of multi-species biofilm at 0.98 μg/mL. Notably, C5 resulted in 98.97% live S. mutans and 77.65% A. naeslundii decreased. Furthermore, the exopolysaccharide was reduced by 88%, along with a sparse and scattered microstructure. The imidazolium salts present low cytotoxicity and remarkable antimicrobial activity against S. mutans in multi-species biofilm, suggesting that they may have a great potential in anti-biofilm clinical applications. [ABSTRACT FROM AUTHOR]

Streptococcus mutans (S. mutans) is a potential pathogenic bacteria of dental caries. However, the level of S. mutans is low in some children with severe early childhood caries (SECC) To evaluate the effect of S. mutans level on dental microbiome and cariogenesis. The oral microbiota was compared between caries-free group (CF) and SECC group.16S rRNA gene sequencing was used for S. mutans level bacterial community analysis. The candidate bacteria that were closely related with S. mutans abundance were identified and confirmed by absolute quantitative real-time PCR in clinical dental plaque samples from CF and SECC groups. Through in-depth analysis of dental plaque microorganism, Leptotrichia, Selenomonas and Prevotella_7 were found in the S. mutans-low group (p < 0.05) and Porphyromonas, Selenomonas_3 were found in the S. mutans-high group (p < 0.05). Through quantitative real-time PCR, Leptotrichia, Selenomonas and Prevotella_7 were identified as the potential biomarkers of SECC when S. mutans was at a low level. Leptotrichia, Selenomonas and Prevotella_7 are identified as potential biomarkers in SECC with a low abundance or without S. mutans. Our study may shed light on the understanding of caries occurrence in SECC with low abundance of S. mutans. S. mutans, Streptococcus mutans; CF, caries-free; SECC, severe early childhood caries; ECC, early childhood caries; rRNA, ribosome RNA; qPCR, Quantitative real-time PCR; OTUs, operational taxonomic units; ANOVA, analysis of variance; LDA, Linear discriminant analysis; LEfSe, Linear discriminant analysis effect size; COG, Groups of proteins; NMDS, Non-MetricMulti-Dimensional Scaling; IL-1β, interleukin −1β; IL-6, interleukin-6; IL-8, interleukin-8; IL-10, interleukin-10. [ABSTRACT FROM AUTHOR]

Here, we explored the role of S. mutans's whole cell and discrete fractions in the degradation of type I collagen and dentinal collagen. Type I collagen gels and human demineralized dentin slabs (DS) were incubated in media alone or with one of the following: overnight (O/N) or newly inoculated (NEW) cultures of S. mutans UA159; intracellular proteins, supernatant or bacterial membranes of O/N cultures. Media from all groups were analyzed for protease-mediated release of the collagen-specific imino acid hydroxyproline. Images of type I collagen and DS were analyzed, respectively. Type I collagen degradation was highest for the supernatant (p < 0.05) fractions, followed by intracellular components and O/N cultures. Collagen degradation for DS samples was highest for O/N samples, followed by supernatant, and intracellular components (p < 0.05). There was lower detectable degradation for both type I collagen and DS from NEW culture samples (p < 0.05), and there was no type I collagen or DS degradation detected for bacterial membrane samples. Structural changes to type I collagen gel and dentinal collagen were observed, respectively, following incubation with S. mutans cultures (O/N and NEW), intracellular components, and supernatant. This study demonstrates that intracellular and extracellular proteolytic activities from S. mutans enable this cariogenic bacterium to degrade type I and dentinal collagen in a growth-phase dependent manner, potentially contributing to the progression of dental caries. [ABSTRACT FROM AUTHOR]

Streptococcus mutans (S. mutans) is one of the primary pathogens responsible for dental caries. Streptococcus gordonii (S. gordonii) is one of the early colonizers of dental plaque and can compete with S. mutans for growth. In the present analysis, we explored key target genes against S. gordonii in S. mutans using 80 S. mutans clinical isolates with varying capabilities against S. gordonii. A principal coordinate analysis revealed significant genetic diversity differences between antagonistic and non-antagonistic groups. Genomic comparisons revealed 33 and 61 genes that were, respectively, positively and negatively correlated with S. mutans against S. gordonii, with RNA-sequencing (RNAseq) highlighting 11 and 43 genes that were, respectively, upregulated and downregulated in the antagonistic group. Through a combination of these results and antiSMASH analysis, we selected 16 genes for qRT-PCR validation in which the expression levels of SMU_137 (malate dehydrogenase, mleS), SMU_138 (malate permease, mleP), SMU_139 (oxalate decarboxylase, oxdC), and SMU_140 (glutathione reductase) were consistent with RNA-seq results. SMU_1315c-1317c (SMU_1315c transport-related gene) and SMU_1908c- 1909c were, respectively, downregulated and upregulated in the antagonistic group. The expression patterns of adjacent genes were closely related, with correlation coefficient values greater than 0.9. These data reveal new targets (SMU_137-140, SMU_1315c-1317c, and SMU_1908c-1909c) for investigating the critical gene clusters against S. gordonii in S. mutans clinical isolates. [ABSTRACT FROM AUTHOR]

Among many factors affecting dental caries, bacteria are its initiating factor. From the perspective of ecological plaque hypothesis, the application of modern molecular biology methods enable scholars to deeply explore the relationship between the microbial population distribution, biodiversity, microbial community changes of dental plaque biofilm and the occurrence of dental caries in children. The decrease in microflora diversity is closely related to the occurrence of dental caries, which can be detected as early as 6 months before the occurrence of dental caries, providing an important basis for caries monitoring and caries risk assessment. Differential bacteria such as Lactobacillus and Veillonella may be used as biomarkers of caries in children to judge the risk of caries in children. However, current studies have shown that the dominant bacteria in the microbial community structure vary in different processes of caries occurrence and development, that the interaction between different flora is still not clear, and that the specific cariogenic mechanism of the oral plaque microbial community in the process of caries occurrence and development has not been clarified. Further research is still needed to explore the changes in plaque microbial diversity and composition during the development of dental caries and to screen specific dental caries biomarkers. This paper also summarizes the related research findings.

Background. Primary dental caries is the most prevalent oral disease among preschool children, which can cause severe damage to teeth and even affect the mental well-being of children. Various studies have demonstrated that the oral microbiome plays a pivotal role in the onset and development of dental caries. However, it remains uncertain about the key microbial markers associated with caries, owing to the limited evidence. Methods. Fifteen S-ECC children and fifteen healthy controls were selected from three-year-old children in this study. Their clinical data and oral saliva samples were collected. Shotgun sequencing was conducted to investigate the microbial differences and the relevant functions between the two groups. Results. We observed no apparent difference in oral microbial community diversity between the two groups. Still, at the genus/species levels, several characteristic genera/species such as Propionibacterium, Propionibacterium acidifaciens, Prevotella denticola, Streptococcus mutans and Actinomyces sp. oral taxon 448/414 increased significantly in S-ECC children, compared with the oral health group. Furthermore, we found that functional pathways involving glycolysis and acid production, such as starch and sucrose metabolism, fructose and mannose metabolism, glycolysis/gluconeogenesis, were prominently up-regulated in the high-caries group. Conclusions. Our study showed that dental caries in children were associated with the alterations in the oral microbiota at the composition and functional levels, which may potentially inspire the exploration of microbial diagnosis or therapeutic treatments. [ABSTRACT FROM AUTHOR]

Background: Streptococcus mutans (S. mutans) is a potential pathogenic bacteria of dental caries. However, the level of S. mutans is low in some children with severe early childhood caries (SECC) Aim: To evaluate the effect of S. mutans level on dental microbiome and cariogenesis. Methods: The oral microbiota was compared between caries-free group (CF) and SECC group.16S rRNA gene sequencing was used for S. mutans level bacterial community analysis. The candidate bacteria that were closely related with S. mutans abundance were identified and confirmed by absolute quantitative real-time PCR in clinical dental plaque samples from CF and SECC groups. Results: Through in-depth analysis of dental plaque microorganism, Leptotrichia, Selenomonas and Prevotella_7 were found in the S. mutans-low group (p < 0.05) and Porphyromonas, Selenomonas_3 were found in the S. mutans-high group (p < 0.05). Through quantitative real-time PCR, Leptotrichia, Selenomonas and Prevotella_7 were identified as the potential biomarkers of SECC when S. mutans was at a low level. Conclusion: Leptotrichia, Selenomonas and Prevotella_7 are identified as potential biomarkers in SECC with a low abundance or without S. mutans. Our study may shed light on the understanding of caries occurrence in SECC with low abundance of S. mutans. [ABSTRACT FROM AUTHOR]

Objective: Biofilm formation under cariogenic conditions contributes to dental caries development, in which Streptococcus mutans (S. mutans) is regarded as the major cariogenic bacteria. Here, we synthesized a series of imidazolium salts. Their properties of antimicrobial and anti-biofilm were investigated. Methods: The microdilution method crystal violet staining, and cell counting Kit-8 assay were used to screen imidazolium salts. Then, the bacterial composition in multi-species biofilm composed of S. mutans, Actinomyces naeslundii, and Streptococcus gordonii was quantified by quantitative PCR. The exopolysaccharide and morphology of the structure of multi-species biofilm were further observed by confocal laser scanning microscopy and scanning electron microscope, respectively. Results: Imidazolium salts exhibited highly antimicrobial activity against oral pathogens, especially for S. mutans. Compounds with ortho-diisopropyl and para-methoxyl on N-moieties as well as bearing ancenaphthyl skeleton (C5) showed the lowest cytotoxicity and most efficient anti-biofilm activity. C5 inhibited approximately 50% of multi-species biofilm at 0.98 µg/mL. Notably, C5 resulted in 98.97% live S. mutans and 77.65% A. naeslundii decreased. Furthermore, the exopolysaccharide was reduced by 88%, along with a sparse and scattered microstructure. Conclusion: The imidazolium salts present low cytotoxicity and remarkable antimicrobial activity against S. mutans in multi-species biofilm, suggesting that they may have a great potential in anti-biofilm clinical applications. [ABSTRACT FROM AUTHOR]

Context: Mechanical performance of dentin is of significant significance for the overall function of the teeth. Remineralization of carious dentin is the ultimate goal in re-establishing the functionality of the affected tissue to regain and maintain the mechanical properties of dentin. Functional remineralization of the affected dentin involves stabilization of both inorganic and organic component, but remineralizing agents stabilize only inorganic content. Hence, to stabilize organic content and to bring in functional remineralization, the use of anti-collagenolytic and anti-elastastic agents was considered for this study. Aims: The aim is to assess and compare the effect of antioxidants pretreatment on remineralization of demineralized dentin-in vitro study. Settings and Design: Experimental randomized analytical- in vitro study. Subjects and Methods: Ninety specimens were subjected to artificial caries lesions and were randomly divided into six groups based on the pretreatment with white tea, and grape seed extract (GSE) followed by casein phosphopeptide amorphous calcium phosphate and casein phosphopeptide amorphous calcium phosphate with fluoride. All the specimens were subjected to pH cycling regimen. The specimens were subjected to Vickers micro-hardness test to obtain the micro-hardness values. Statistical Analysis Used: The values were statistically analyzed using one-way analysis of variance. Results: After pH cycling, GSE showed a significant increase in micro-hardness values (46.57 ± 3.51 VHN), followed by white tea (42.56 ± 5.20) with the level of significance <0.05. Conclusions: Results of this study showed that naturally occurring antioxidants, i.e., 10% White tea and 6.5% GSE can be used as pretreatment regime before remineralization treatment. [ABSTRACT FROM AUTHOR]

Streptococcus mutans is one of the major cariogenic pathogens in the oral cavity. The dlt operon is responsible for the process of D-alanylation of lipoteichoic acid and is related to the virulence of S. mutans . The dlt operon contributes to the adhesion, biofilm formation, stress response, interspecies competitiveness and autolysis of S. mutans . In addition, we have summarized the possible regulatory networks of the dlt operon. This review highlights the significant role of the dlt operon in S. mutans and provides new ideas for ecological caries prevention.

Introduction: Dental caries is defined as a pathological breakdown of the tooth. It is an infectious phenomenon involving a multifactorial aetiology. The impact of drugs on cariogenic risk has been poorly investigated.Objectives: In this study, we identified drugs suspected to induce dental caries as adverse drug reactions (ADRs) and then studied a possible pathogenic mechanism for each drug that had a statistically significant disproportionality.Methods: We extracted individual case safety reports of dental caries associated with drugs from VigiBase® (the World Health Organization global individual case safety report database). We calculated disproportionality for each drug with a reporting odds ratio (ROR) and 99% confidence interval. We analysed the pharmacodynamics of each drug that had a statistically significant disproportionality.Results: In VigiBase®, 5229 safety reports for dental caries concerning 733 drugs were identified. Among these drugs, 88 had a significant ROR, and for 65 of them (73.9%), no information about dental caries was found in the summaries of the product characteristics, the Micromedex® DRUGDEX, or the Martindale databases. Regarding the pharmacological classes of drugs involved in dental caries, we identified bisphosphonates, atropinic drugs, antidepressants, corticoids, immunomodulating drugs, antipsychotics, antiepileptics, opioids and β2-adrenoreceptor agonist drugs. Regarding possible pathogenic mechanisms for these drugs, we identified changes in salivary flow/composition for 54 drugs (61.4%), bone metabolism changes for 31 drugs (35.2%), hyperglycaemia for 32 drugs (36.4%) and/or immunosuppression for 23 drugs (26.1%). For nine drugs (10.2%), the mechanism was unclear.Conclusion: We identified 88 drugs with a significant positive disproportionality for dental caries. Special attention has to be paid to bisphosphonates, atropinic drugs, immunosuppressants and drugs causing hyperglycaemia. [ABSTRACT FROM AUTHOR]

Streptococcus mutans is a cariogenic bacterium that contributes to dental caries due to its ability to produce lactic acid, which acidifies the local environment. The potential of S. mutans to respond to environmental stress and tolerate low pH is essential for its survival and predominance in caries lesions. Small noncoding RNAs (sRNAs) have been reported to be involved in bacterial stress and virulence. Few studies have investigated the sRNAs of S. mutans and the function of these sRNAs remains to be elucidated. In the present study, the association between sRNA133474 and acid tolerance, including potential underlying mechanisms, were investigated within clinical strains of S. mutans. From pediatric dental plaques, 20 strains of S. mutans were isolated. An acid killing assay was performed to analyze acid tolerance of S. mutans. Expression patterns of sRNA133474 were investigated during various growth phases under various acidic conditions via reverse transcription-quantitative polymerase chain reaction. RNA predator and Kyoto Encyclopedia of Genes and Genomes analyses were performed to predict target mRNAs of sRNA133474 and to examine the involvement of putative pathways of target mRNAs, respectively. The results of the present study demonstrated that sRNA133474 activity was growth phase-dependent, and two distinct expression patterns were identified in 10 clinical strains. At pH 5.5 and 7.5 the expression levels of sRNA133474 were significantly different, and high-acid tolerant strains exhibited reduced expression levels of sRNA133474 compared with low-acid tolerant strains. A correlation between sRNA133474 expression levels and acid tolerance was observed in 20 clinical isolates of S. mutans (r=-0.6298, P<0.01). Finally, five target mRNAs (liaS, liaR, comE, covR and ciaR) involved in the two-component system (TCS) were selected for further evaluation; the expression levels of three target mRNAs {liaR, ciaR and covR) were negatively correlated with sRNA133474 expression levels. In conclusion, the results of the present study suggested that S. mutans may utilize sRNA133474 to orchestrate TCSs for optimal adaption to acidic pH in clinical strains. [ABSTRACT FROM AUTHOR]

Background: Alterations of oral microbiota are the main cause of the progression of caries. The goal of this study was to characterize the oral microbiota in childhood caries based on single-molecule real-time sequencing. Methods: A total of 21 preschoolers, aged 3-5 years old with severe early childhood caries, and 20 age-matched, caries-free children as controls were recruited. Saliva samples were collected, followed by DNA extraction, Pacbio sequencing, and phylogenetic analyses of the oral microbial communities. Results: Eight hundred and seventy six species derived from 13 known bacterial phyla and 110 genera were detected from 41 children using Pacbio sequencing. At the species level, 38 species, including Veillonella spp., Streptococcus spp., Prevotella spp., and Lactobacillus spp., showed higher abundance in the caries group compared to the caries-free group (p < 0.05). The core microbiota at the genus and species levels was more stable in the caries-free micro-ecological niche. At follow-up, oral examinations 6 months after sample collection, development of new dental caries was observed in 5 children (the transitional group) among the 21 caries free children. Compared with the caries-free children, in the transitional and caries groups, 6 species, which were more abundant in the caries-free group, exhibited a relatively low abundance in both the caries group and the transitional group (p < 0.05). We conclude that Abiotrophia spp., Neisseria spp., and Veillonella spp., might be associated with healthy oral microbial ecosystem. Prevotella spp., Lactobacillus spp., Dialister spp., and Filifactor spp. may be related to the pathogenesis and progression of dental caries. [ABSTRACT FROM AUTHOR]

Objective: To compare the effects of different treatment methods used for the enamel damage, on the shear bond strength (SBS) and fracture mode of orthodontic brackets.Materials and Methods: Freshly-extracted 140 premolars were randomly allocated to seven groups: Group I was considered as the control of other groups. The remaining groups were exposed to demineralization. In group II, brackets were directly bonded to the demineralized enamel surface. CPP-ACP paste (GC Tooth Mousse), fluoride varnish (Bifluorid 12), microabrasion with a mixture prepared with 18% hydrochloric acid and fine pumice powder, microabrasion with an agent (Opalustre) and resin infiltrant (Icon®) were applied in Groups III, IV, V, VI and VII, respectively. The specimens were tested for SBS and bond failures were scored according to the Adhesive Remnant Index (ARI). Analysis of variance and Tukey tests were used to compare the SBS of the groups. ARI scores were compared with G-test. The statistical significance was set at p < 0.05 level.Results: Statistically significant differences were found among seven groups (F = 191.697; p < 0.001). The SBSs of groups I (mean = 18.8 ± 2.0 MPa) and VII (mean = 19.1 ± 1.4 MPa) were significantly higher than the other groups. No statistically significant difference was found between groups IV (mean = 11.5 ± 1.2 MPa) and V (mean = 12.6 ± 1.5 MPa). The differences in ARI scores of the groups were statistically significant (p < 0.01).Conclusions: All demineralization treatment methods improve bonding to demineralized enamel. Resin infiltrant application after demineralization showed similar bond strength values as intact enamel. [ABSTRACT FROM AUTHOR]

Background Although high-fructose corn syrup ( HFCS) as a kind of sugar has been widely used in manufactured foods recently, there is little information available regarding its cariogenicity. The aim of this study was to evaluate the cariogenic potential of HFCS. Methods Streptococcus mutans UA159 was inoculated into HFCS media and cultivated. The pH of each culture was measured to assess acidogenicity. Spectrophotometric turbidity was measured to determine the percentage of adherence. Confocal laser scanning microscopy and SYTO-9 staining were employed to observe biofilm formation. Sucrose media was used as a positive control. Results The ΔpH in HFCS media was significantly larger than that in sucrose media and the pH in HFCS media decreased faster (p < 0.05). The percentage of adherence of S. mutans in HFCS media was significantly lower than that in sucrose media (p < 0.05). The biofilm formed in sucrose media was significantly thicker than that in HFCS media (p < 0.05). Conclusions The results of this study suggest that the cariogenicity of S. mutans in the presence of HFCS may differ compared to its cariogenicity in the presence of sucrose. Further in vivo studies need to be undertaken to resolve this uncertainty. [ABSTRACT FROM AUTHOR]

The article investigates the impact on dental caries in rats of decreased vascularity due to ligation of major vessels to the teeth, and salivary adenectomy. An experiment is described and results are discussed. Ligation produced greater dental caries in the maxillary and mandibular teeth, while the adenectomy promoted caries only in the latter.

Background: A number of studies on oral microbial diversity of early childhood caries (ECC) have tended to focus on mid- or late-stage of ECC, with a lack of research into early stage of tooth eruption and maternal influence. The aims of this study are to compare the supragingival plaque biofilm microbiota diversity between mothers with or without dental caries and their 12-month-old infants, and to explore the relationship of microbial diversity between infants and their mothers, using sequencing analysis. Methods: Supragingival plaque biofilm samples were collected from 20 pairs of mothers and their infants aged 12 months (10 mothers with dental caries and their 10 infants vs. 10 caries-free mothers and their 10 infants). The basic information of the mothers and infants had been collected through self-completed questionnaire. Pooled plaque biofilm DNA was extracted and DNA amplicons of the V4-V5 hypervariable region of the bacterial 16S rRNA gene were generated. Ilumina Miseq PE300 was used for 16S rRNA sequencing. Results: The results showed that high bacterial diversity was noted in the plaque biofilm of infants and their mothers with or without dental caries (dental caries mothers vs. caries-free mothers: 774 operational taxonomical units (OTUs) vs. 761 OTUs at a 3% divergence; infants whose mothers have dental caries vs. infants whose mothers are caries-free: 815 OTUs vs. 684 OTUs at 3% divergence). The Shannon microbial diversity index showed no statistically significant differences both on infants and their mothers between two groups (p > 0.05). Mother's microbial diversity was higher than infants' based on Shannon index (p < 0.05). Significant positive correlations were found between mothers' and their infants' Shannon index (r = 0.656, p = 0.002). Conclusion: Oral microbial diversity is significantly different between mothers and infants regardless of dental caries status, but no significant difference was found between mothers with and without dental caries or between their infants. Mother's oral microbial diversity has an overall impact on the infants aged 12 months. [ABSTRACT FROM AUTHOR]

Acid resistance is one of key properties assisting the survival of cariogenic bacteria in a dental caries environment, but only a few genes conferring acid resistance have been identified to data. Functional metagenomics provides a systematic method for investigating commensal DNA to identify genes that encode target functions. Here, the host strain Escherichia coli DH10B and a constructed bidirectional transcription vector pSKII+-lacZ contributed to the construction of a metagenomic library, and 46.6 Mb of metagenomic DNA was cloned from carious supragingival plaque of 8children along with screening for lethal functionality. The screen identified 2 positive clones that exhibited a similar aciduric phenotype to that of the positive controls. Bioinformatic analysis revealed that these two genes encoded an ATP/GTP-binding protein and a malate dehydrogenase. Moreover, we also performed functional screening of Streptococcus mutans, since it is one of the predominant cariogenic strains but was not identified in our initial screening. Five positive clones were retrieved. In conclusion, our improved functional metagenomics screening method helped in the identification of important acid resistance genes, thereby providing new insights into the mechanism underlying caries formation as well as in the prevention and treatment of early childhood caries (ECC). [ABSTRACT FROM AUTHOR]

Dental caries is a chronic infectious disease that occurs in the hard tissue of teeth under the influence of multiple factors, among which bacteria being a key factor. Streptococcus mutans ( S. mutans ) is considered a major pathogen that causes caries. Secondary metabolites, including bacteriocins and polyketides/non-ribosomal peptides, are a class of small-molecule compounds synthesized by S. mutans . To date, polyketides/non-ribosomal peptides identified in S. mutans include mutanobactin, mutanocyclin, and mutanofactin, which are synthesized by the mub , muc , and muf biosynthetic gene clusters, respectively. These polyketides/non-ribosomal peptides play important roles in bacterial inter-species competition, oxidative stress, and biofilm formation. In this review, we provided an overview of the synthesis, function and regulation of three polyketides/non-ribosomal peptides of S. mutans , including mutanobactin, mutanocyclin, and mutanofactin, aiming to provide new insights into the cariogenic mechanism of S. mutans and to promote the better management of dental caries., (Copyright© by Editorial Board of Journal of Sichuan University (Medical Sciences).)

Lactobacillus is the first microorganism found to be closely associated with dental caries. It demonstrates acidogenicity, aciduricity, and the ability to bind with collagen and to synthesize extracellular polysaccharides to promote bacterial adhesion. Some lactobacilli inhibit the growth of cariogenic bacteria by producing antibacterial compounds or metabolites, competing with cariogenic bacteria for adhesion sites or co-aggregation, or regulating the expression of genes related to cariogenic virulence. Therefore, researchers have, in recent years, experimented with applying Lactobacillus as probiotics in the prevention and control of caries. However, the cariogenic mechanism of Lactobacillus is still not fully understood, and the potential effects, presumably beneficial, of specific Lactobacillus on oral and intestinal microecology remain unknown. More research needs to be done to combine both the cariogenic and probiotic properties of Lactobacillus , and to comprehensively evaluate the effects of Lactobacillus on oral and systemic health. We, herein, summarized research progress in the cariogenicity and caries prevention effect of Lactobacillus , focusing on a discussion of the role of Lactobacillus in cariogenesis, the development of dental caries, and clinical prevention and control of dental caries, in order to provide new ideas and references for the prevention and control of dental caries., (Copyright© by Editorial Board of Journal of Sichuan University (Medical Sciences).)