Optimization and Evaluation of the 30S-S11 rRNA Gene for Taxonomic Profiling of Oral Streptococci.

Dental caries is a multifactorial disease driven by interactions between the highly complex microbial biofilm community and host factors like diet, oral hygiene habits, and age. The oral streptococci are one of the most dominant members of the plaque biofilm and are implicated in disease but also in maintaining oral health. Current methods used for studying the supragingival plaque community commonly sequence portions of the16S rRNA gene, which often cannot taxonomically resolve members of the streptococcal community past the genus level due to their sequence similarity. The goal of this study was to design and evaluate a more reliable and cost-effective method to identify oral streptococci at the species level by applying a new locus, the 30S-S11 rRNA gene, for high-throughput amplicon sequencing. The study results demonstrate that the newly developed single-copy 30S-S11 gene locus resolved multiple amplicon sequence variants (ASVs) within numerous species, providing much improved taxonomic resolution over 16S rRNA V4. Moreover, the results reveal that different ASVs within a species were found to change in abundance at different stages of caries progression. These findings suggest that strains of a single species may perform distinct roles along a biochemical spectrum associated with health and disease. The improved identification of oral streptococcal species will provide a better understanding of the different ecological roles of oral streptococci and inform the design of novel oral probiotic formulations for prevention and treatment of dental caries. IMPORTANCE The microbiota associated with the initiation and progression of dental caries has yet to be fully characterized. Although much insight has been gained from 16S rRNA hypervariable region DNA sequencing, this approach has several limitations, including poor taxonomic resolution at the species level. This is particularly relevant for oral streptococci, which are abundant members of oral biofilm communities and major players in health and caries disease. Here, we develop a new method for taxonomic profiling of oral streptococci based on the 30S-S11 rRNA gene, which provides much improved resolution over 16S rRNA V4 (resolving 10 as opposed to 2 species). Importantly, 30S-S11 can resolve multiple amplicon sequence variants (ASVs) within species, providing an unprecedented insight into the ecological progression of caries. For example, our findings reveal multiple incidences of different ASVs within a species with contrasting associations with health or disease, a finding that has high relevance toward the informed design of prebiotic and probiotic therapy.

Subgingival microbiome of deep and shallow periodontal sites in patients with rheumatoid arthritis: a pilot study.

BACKGROUND: Subgingival microbiome in disease-associated subgingival sites is known to be dysbiotic and significantly altered. In patients with rheumatoid arthritis (RA), the extent of dysbiosis in disease- and health-associated subgingival sites is not clear. METHODS: 8 RA and 10 non-RA subjects were recruited for this pilot study. All subjects received full oral examination and underwent collection of subgingival plaque samples from both shallow (periodontal health-associated, probing depth ≤ 3mm) and deep subgingival sites (periodontal disease-associated, probing depth ≥ 4 mm). RA subjects also had rheumatological evaluation. Plaque community profiles were analyzed using 16 S rRNA sequencing. RESULTS: The phylogenetic diversity of microbial communities in both RA and non-RA controls was significantly higher in deep subgingival sites compared to shallow sites (p = 0.022), and the overall subgingival microbiome clustered primarily according to probing depth (i.e. shallow versus deep sites), and not separated by RA status. While a large number of differentially abundant taxa and gene functions was observed between deep and shallow sites as expected in non-RA controls, we found very few differentially abundant taxa and gene functions between deep and shallow sites in RA subjects. In addition, compared to non-RA controls, the UniFrac distances between deep and shallow sites in RA subjects were smaller, suggesting increased similarity between deep and shallow subgingival microbiome in RA. Streptococcus parasanguinis and Actinomyces meyeri were overabundant in RA subjects, while Gemella morbillorum, Kingella denitrificans, Prevotella melaninogenica and Leptotrichia spp. were more abundant in non-RA subjects. CONCLUSIONS: The aggregate subgingival microbiome was not significantly different between individuals with and without rheumatoid arthritis. Although the differences in the overall subgingival microbiome was driven primarily by probing depth, in contrast to the substantial microbiome differences typically seen between deep and shallow sites in non-RA patients, the microbiome of deep and shallow sites in RA patients were more similar to each other. These results suggest that factors associated with RA may modulate the ecology of subgingival microbiome and its relationship to periodontal disease, the basis of which remains unknown but warrants further investigation.

Site-Specific Profiling of the Dental Mycobiome Reveals Strong Taxonomic Shifts during Progression of Early-Childhood Caries.

Dental caries is one of the most common diseases worldwide. Bacteria and fungi are both commensals in the oral cavity; however, most research regarding caries has focused on bacterial impacts. The oral fungal mycobiome associated with caries is not well characterized, and its role in disease is unclear. ITS1 amplicon sequencing was used to generate taxonomic profiles from site-specific supragingival plaque samples (n = 82) obtained from 33 children with different caries status. Children were either caries free (CF), caries active with enamel lesions (CAE), or caries active with dentin lesions (CA). Plaque samples were collected from caries-free surfaces (PF) and from enamel (PE) and dentin (PD) lesions. Taxonomic profiles representing the different categorizations (CF-PF, CAE-PF, CAE-PE, CA-PF, CA-PE, and CA-PD) were used to characterize the mycobiome and its change through disease progression. A total of 139 fungal species were identified. Candida albicans was the most abundant species, followed by Candida dubliniensis We found that severely progressed plaque communities (CA-PD) were significantly different from healthy plaque communities (CF-PF). A total of 32 taxa were differentially abundant across the plaque categories. C. albicans, C. dubliniensis, Nigrospora oryzae, and an unclassified Microdochium sp. were correlated with caries, whereas 12 other taxa were correlated with health. C. dubliniensis increased steadily as caries progressed, suggesting that C. dubliniensis may play an important role in caries pathogenicity. In contrast, four health-associated fungal taxa have the potential to antagonize the cariogen Streptococcus mutans via xylitol production, suggesting a possible fungal mechanism that could contribute to maintenance of dental health.IMPORTANCE Early-childhood caries is one of the most prevalent diseases in children worldwide and, while preventable, remains a global public health concern. Untreated cavities are painful and expensive and can lead to tooth loss and a lower quality of life. Caries are driven by acid production via microbial fermentation of dietary carbohydrates, resulting in enamel erosion. While caries is a well-studied disease, most research has focused on bacterial impacts, even though fungi are commensal organisms living within the plaque biofilm. There is very little known about how fungi impact caries pathogenicity. The elucidation of fungal taxa involved in caries disease progression is necessary for a more holistic view of the human oral microbiome. Data from this study will improve our understanding of how the fungal community changes as disease progresses and provide insight into the complex etiology of dental caries, which is necessary for the development of treatment plans and preventative measures.

Diversity in Antagonistic Interactions between Commensal Oral Streptococci and Streptococcus mutans.

Arginine metabolism via the arginine deiminase system (ADS) of oral bacteria generates ammonia, which can increase the pH of oral biofilms and decrease the risk for dental caries. Antagonistic interactions between ADS-positive and cariogenic bacteria in oral biofilms may be an important ecological determinant of caries. This study investigated the antagonistic potential and mechanisms of clinical isolates of arginolytic streptococci on and by Streptococcus mutans UA159, a well-characterized cariogenic human isolate. Low-passage isolates of Streptococcus gordonii, Streptococcus sanguinis, Streptococcus parasanguinis, Streptococcus australis, and Streptococcus cristatus inhibited the growth of S. mutans to various degrees when they were inoculated on growth media first or simultaneously with S. mutans. The antagonistic effects of arginolytic strains against S. mutans and the production of H2O2 by these strains were enhanced during growth in a less-rich medium or when galactose was substituted for glucose as the primary carbohydrate source. Pyruvate oxidase was the dominant pathway for H2O2 production by arginolytic strains, but lactate oxidase activity was also detected in some strains of S. gordonii and S. cristatus. UA159 inhibited the growth of all tested arginolytic strains when inoculated first, especially in aerobic conditions. However, the antagonistic effects of S. mutans on certain strains of S. gordonii and S. australis were not observed during anaerobic growth in the presence of arginine. Thus, arginolytic commensal streptococci may have a synergistically positive impact on the ecology of oral biofilms by moderating biofilm pH while antagonizing the growth and virulence of caries pathogens.

Microbiomes of Site-Specific Dental Plaques from Children with Different Caries Status.

The oral microbiota associated with the initiation and progression of dental caries has yet to be fully characterized. The Human Oral Microbe Identification Using Next-Generation Sequencing (HOMINGS) approach was used to analyze the microbiomes of site-specific supragingival dental plaques from children with different caries status. Fifty-five children (2 to 7 years of age) were assessed at baseline and at 12 months and grouped as caries free (CF), caries active with enamel lesions (CAE), and caries active with dentin carious lesions (CA). Plaque samples from caries-free tooth surfaces (PF) and from enamel carious lesions (PE) and dentin carious lesions (PD) were collected. 16S community profiles were obtained by HOMINGS, and 408 bacterial species and 84 genus probes were assigned. Plaque bacterial communities showed temporal stability, as there was no significant difference in beta diversity values between the baseline and 12-month samples. Irrespective of collection time points, the microbiomes of healthy tooth surfaces differed substantially from those found during caries activity. All pairwise comparisons of beta diversity values between groups were significantly different (P < 0.05), except for comparisons between the CA-PF, CAE-PE, and CA-PE groups. Streptococcus genus probe 4 and Neisseria genus probe 2 were the most frequently detected taxa across the plaque groups, followed by Streptococcus sanguinis, which was highly abundant in CF-PF. Well-known acidogenic/aciduric species such as Streptococcus mutans, Scardovia wiggsiae, Parascardovia denticolens, and Lactobacillus salivarius were found almost exclusively in CA-PD. The microbiomes of supragingival dental plaque differ substantially among tooth surfaces and children of different caries activities. In support of the ecological nature of caries etiology, a steady transition in community species composition was observed with disease progression.

Oral microbiota transplant: a potential new therapy for oral diseases.

Dental caries and periodontitis are amongst the most common diseases affecting humans worldwide. There is an evolving trend for dental and medical research to share knowledge on the etiology and promising therapies for human diseases. Inspired by the success of fecal microbiota transplant to manage gastro-intestinal disordes, oral microbiome transplant has been proposed but not yet tested in humans. This article critically reviews the potential of oral microbiome transplant for managing oral diseases.

A Highly Arginolytic Streptococcus Species That Potently Antagonizes Streptococcus mutans.

The ability of certain oral biofilm bacteria to moderate pH through arginine metabolism by the arginine deiminase system (ADS) is a deterrent to the development of dental caries. Here, we characterize a novel Streptococcus strain, designated strain A12, isolated from supragingival dental plaque of a caries-free individual. A12 not only expressed the ADS pathway at high levels under a variety of conditions but also effectively inhibited growth and two intercellular signaling pathways of the dental caries pathogen Streptococcus mutans. A12 produced copious amounts of H2O2 via the pyruvate oxidase enzyme that were sufficient to arrest the growth of S. mutans. A12 also produced a protease similar to challisin (Sgc) of Streptococcus gordonii that was able to block the competence-stimulating peptide (CSP)-ComDE signaling system, which is essential for bacteriocin production by S. mutans. Wild-type A12, but not an sgc mutant derivative, could protect the sensitive indicator strain Streptococcus sanguinis SK150 from killing by the bacteriocins of S. mutans. A12, but not S. gordonii, could also block the XIP (comX-inducing peptide) signaling pathway, which is the proximal regulator of genetic competence in S. mutans, but Sgc was not required for this activity. The complete genome sequence of A12 was determined, and phylogenomic analyses compared A12 to streptococcal reference genomes. A12 was most similar to Streptococcus australis and Streptococcus parasanguinis but sufficiently different that it may represent a new species. A12-like organisms may play crucial roles in the promotion of stable, health-associated oral biofilm communities by moderating plaque pH and interfering with the growth and virulence of caries pathogens.

Insights into the Virulence Traits of Streptococcus mutans in Dentine Carious Lesions of Children with Early Childhood Caries.

Streptococcus mutans is an oral bacterium considered to play a major role in the development of dental caries. This study aimed to investigate the prevalence of S. mutans in active and arrested dentine carious lesions of children with early childhood caries and to examine the expression profile of selected S. mutans genes associated with survival and virulence, within the same carious lesions. Dentine samples were collected from 29 active and 16 arrested carious lesions that were diagnosed in preschool children aged 2-5 years. Total RNA was extracted from the dentine samples, and reverse transcription quantitative real-time PCR analyses were performed for the quantification of S. mutans and for analyses of the expression of S. mutans genes associated with bacterial survival (atpD, nox, pdhA) and virulence (fabM and aguD). There was no statistically significant difference in the prevalence of S. mutans between active and arrested carious lesions. Expression of the tested genes was detected in both types of carious dentine. The pdhA (p = 0.04) and aguD (p = 0.05) genes were expressed at higher levels in arrested as compared to active lesions. Our findings revealed that S. mutans is part of the viable microbial community in active and arrested dentine carious lesions. The increase in expression of the pdhA and aguD genes in arrested lesions is likely due to the unfavourable environmental conditions for microbial growth, inherent to this type of lesions.

Characterization of the arginolytic microflora provides insights into pH homeostasis in human oral biofilms.

A selected group of oral bacteria commonly associated with dental health is capable of producing alkali via the arginine deiminase system (ADS), which has a profound impact on the pH of human oral biofilms. An increased risk for dental caries has been associated with reduced ADS activity of the bacteria in oral biofilms. Arginolytic bacterial strains from dental plaque samples of caries-free and caries-active adults were isolated and characterized to investigate the basis for differences in plaque ADS activity between individuals. Fifty-six ADS-positive bacterial strains were identified by 16S rRNA gene sequencing, and their ADS activity levels were compared under standard growth conditions. The spectrum of bacterial ADS activity ranged from 45.2 to 688.0 units (mg protein)(-1). Although Streptococcus sanguinis was the most prevalent species, other Streptococcus sp. were also represented. Biochemical assays carried out using 27 ADS-positive strains under conditions known to induce or repress ADS gene expression showed substantial variation in arginolytic activity in response to pH, oxygen and the availability of carbohydrate or arginine. This study reveals that the basis for the wide spectrum of arginolytic expression observed among clinical strains is, at least in part, attributable to differences in the regulation of the ADS within and between species. The results provide insights into the microbiological basis for intersubject differences in ADS activity in oral biofilms and enhance our understanding of dental caries as an ecologically driven disease in which arginine metabolism moderates plaque pH and promotes dental health.

Heterogeneous lineage-specific arginine deiminase expression within dental microbiome species.

Arginine catabolism by the bacterial arginine deiminase system (ADS) has anticariogenic properties through the production of ammonia, which modulates the pH of the oral environment. Given the potential protective capacity of the ADS pathway, the exploitation of ADS-competent oral microbes through pre- or probiotic applications is a promising therapeutic target to prevent tooth decay. To date, most investigations of the ADS in the oral cavity and its relation to caries have focused on indirect measures of activity or on specific bacterial groups, yet the pervasiveness and rate of expression of the ADS operon in diverse mixed microbial communities in oral health and disease remain an open question. Here, we use a multivariate approach, combining ultra-deep metatranscriptomic sequencing with paired metataxonomic and in vitro citrulline quantification to characterize the microbial community and ADS operon expression in healthy and late-stage cavitated teeth. While ADS activity is higher in healthy teeth, we identify multiple bacterial lineages with upregulated ADS activity on cavitated teeth that are distinct from those found on healthy teeth using both reference-based mapping and de novo assembly methods. Our dual metataxonomic and metatranscriptomic approach demonstrates the importance of species abundance for gene expression data interpretation and that patterns of differential expression can be skewed by low-abundance groups. Finally, we identify several potential candidate probiotic bacterial lineages within species that may be useful therapeutic targets for the prevention of tooth decay and propose that the development of a strain-specific, mixed-microbial probiotic may be a beneficial approach given the heterogeneity of taxa identified here across health groups. IMPORTANCE: Tooth decay is the most common preventable chronic disease, affecting more than two billion people globally. The development of caries on teeth is primarily a consequence of acid production by cariogenic bacteria that inhabit the plaque microbiome. Other bacterial strains in the oral cavity may suppress or prevent tooth decay by producing ammonia as a byproduct of the arginine deiminase metabolic pathway, increasing the pH of the plaque biofilm. While the benefits of arginine metabolism on oral health have been extensively documented in specific bacterial groups, the prevalence and consistency of arginine deiminase system (ADS) activity among oral bacteria in a community context remain an open question. In the current study, we use a multi-omics approach to document the pervasiveness of the expression of the ADS operon in both health and disease to better understand the conditions in which ADS activity may prevent tooth decay.

The combined use of chlorhexidine and fluoride therapy can reduce the risk for dental caries.

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION: A randomized clinical trial of anticaries therapies targeted according to risk assessment (caries management by risk assessment). Featherstone JDB, White JM, Hoover CI, Rapozo-Hilo M, Weintraub JA, Wilson RS, Zhan L, Gansky SA. Caries Res 2012;46(2):118-29. REVIEWER: Marcelle M. Nascimento, DDS, MS, PhD PURPOSE/QUESTION: The study sought to determine whether the use of preventive and restorative therapies based on individual caries risk for 2 years could reduce caries increment compared to traditional dental care provided at the University of California, San Francisco School of Dentistry (UCSF) SOURCE OF FUNDING: The main research support was provided by NIH/NIDCR and the oral products used in the study were provided by Proctor and Gamble, Omnii Oral Pharmaceuticals and Oral B TYPE OF STUDY/DESIGN: Randomized controlled trial LEVEL OF EVIDENCE: Level 1: Good-quality, patient-oriented evidence STRENGTH OF RECOMMENDATION GRADE: Not applicable.

Evidence-based clinical practice guideline on restorative treatments for caries lesions: A report from the American Dental Association.

BACKGROUND: An expert panel convened by the American Dental Association (ADA) Council on Scientific Affairs together with the ADA Science and Research Institute's program for Clinical and Translational Research conducted a systematic review and developed recommendations for the treatment of moderate and advanced cavitated caries lesions in patients with vital, nonendodontically treated primary and permanent teeth. TYPES OF STUDIES REVIEWED: The authors searched for systematic reviews comparing carious tissue removal (CTR) approaches in Ovid MEDLINE, Embase, Cochrane Database of Systematic Reviews, and Trip Medical Database. The authors also conducted a systematic search for randomized controlled trials comparing direct restorative materials in Ovid MEDLINE, Embase, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform. The authors used the Grading of Recommendations Assessment, Development, and Evaluation approach to assess the certainty of the evidence and formulate recommendations. RESULTS: The panel formulated 16 recommendations and good practice statements: 4 on CTR approaches specific to lesion depth and 12 on direct restorative materials specific to tooth location and surfaces involved. The panel conditionally recommended for the use of conservative CTR approaches, especially for advanced lesions. Although the panel conditionally recommended for the use of all direct restorative materials, they prioritized some materials over the use of others for certain clinical scenarios. PRACTICAL IMPLICATIONS: The evidence suggests that more conservative CTR approaches may decrease the risk of adverse effects. All included direct restorative materials may be effective in treating moderate and advanced caries lesions on vital, nonendodontically treated primary and permanent teeth.

Direct materials for restoring caries lesions: Systematic review and meta-analysis-a report of the American Dental Association Council on Scientific Affairs.

BACKGROUND: The goal of restoring caries lesions is to protect the pulp, prevent progression of the disease process, and restore the form and function of the tooth. The purpose of this systematic review was to determine the effect of different direct restorative materials for treating cavitated caries lesions on anterior and posterior primary and permanent teeth. TYPE OF STUDIES REVIEWED: The authors included parallel and split-mouth randomized controlled trials comparing the effectiveness of direct restorative materials commercially available in the United States placed in vital, nonendodontically treated primary and permanent teeth. Pairs of reviewers independently conducted study selection, data extraction, and assessments of risk of bias and certainty of the evidence using the Grading of Recommendations Assessment, Development and Evaluation approach. The authors conducted pair-wise meta-analyses to summarize the evidence and calculated measures of association and their 95% CIs. RESULTS: Thirty-eight randomized controlled trials were eligible for analysis, which included data on Class I and Class II restorations on primary teeth and Class I, Class II, Class III, Class V, and root surface restorations on permanent teeth. Included studies assessed the effect of amalgam, resin composite, compomer, conventional glass ionomer cement, resin-modified glass isomer cement, and preformed metal crowns. Moderate to very low certainty evidence suggested varying levels of effectiveness across restorative materials. CONCLUSIONS AND PRACTICAL IMPLICATIONS: Owing to a relatively low event rate across various outcomes indicating restoration failure, there was limited evidence to support important differences between direct restorative materials used in practice.

Prepregnancy BMI, gestational weight gain and offspring caries experience: Avon longitudinal study of parents and children.

Pre-existing maternal overweight/obesity and pregnancy weight gain are associated with adverse birth outcomes such as low birth weight and prematurity, which may increase the risk of developmental tooth defects and early childhood caries. We sought to investigate the association between prepregnancy BMI, gestational weight gain (GWG) and the risk of early childhood caries. Data from 1,429 mother-offspring participants of the 1991/1992 Avon Longitudinal Study of Parents and Children were analyzed. The exposures were prepregnancy BMI (under/normal weight vs. overweight/obese), and gestational weight gain (GWG) based on the Institute of Medicine's recommended levels. The main outcome measured was offspring caries experience determined by clinical oral examinations at three time points. Log binomial regression estimated risk ratios and 95% confidence intervals. Seventy six percent (76%) of the mothers were under/normal weight prepregnancy, 39% and 26% respectively gained less and more than the recommended weight for their prepregnancy BMI during pregnancy. Being overweight/obese prepregnancy was associated with unadjusted RR (95% CI) of offspring caries of 1.16 (0.90, 1.51) at 31-months, 1.20 (0.96, 1.49) at 43-months and 1.09 (0.91, 1.30) at 61-months. GWG less than recommended was associated with higher unadjusted offspring caries experience of 1.13 (0.86, 1.48), 1.17 (0.92, 1.48) and 1.04 (0.87, 1.25) at 31-months, 43-months and 61-months respectively. There was insufficient evidence to indicate an association between prepregnancy BMI and gestational weight gain on offspring caries experience risk.

Incorporation of Arginine to Commercial Orthodontic Light-Cured Resin Cements-Physical, Adhesive, and Antibacterial Properties.

(1) Background: The amino acid arginine is now receiving great attention due to its potential anti-caries benefits. The purpose of this in vitro study was to evaluate the shear bond strength (SBS), ultimate tensile strength (UTS), and antimicrobial potential (CFU) of two arginine-containing orthodontic resin cements. (2) Methods: Forty bovine incisors were separated into four groups (n = 10): Orthocem, Orthocem + arginine (2.5 wt%), Transbond XT, and Transbond XT + arginine (2.5 wt%). The brackets were fixed to the flat surface of the enamel, and after 24 h the SBS was evaluated using the universal testing machine (Instron). For the UTS test, hourglass samples (n = 10) were made and tested in a mini-testing machine (OM-100, Odeme). For the antibacterial test (colony forming unit-CFU), six cement discs from each group were made and exposed to Streptococcus mutans UA159 biofilm for 7 days. The microbiological experiment was performed by serial and triplicate dilutions. The data from each test were statistically analyzed using a two-way ANOVA, followed by Tukey's test (α = 0.05). (3) Results: The enamel SBS mean values of Transbond XT were statistically higher than those of Orthocem, both with and without arginine (p = 0.02033). There was no significant difference in the SBS mean values between the orthodontic resin cements, either with or without arginine (p = 0.29869). The UTS of the Transbond XT was statistically higher than the Orthocem, but the addition of arginine at 2.5 wt% did not influence the UTS for either resin cement. The Orthocem + arginine orthodontic resin cement was able to significantly reduce S. mutans growth, but no difference was observed for the Transbond XT (p = 0.03439). (4) Conclusion: The incorporation of arginine to commercial orthodontic resin cements may be an efficient preventive strategy to reduce bacterial growth without compromising their adhesive and mechanical properties.

Concordance between preoperative and postoperative assessments of primary caries lesion depth: results from the Dental PBRN.

This study investigated the concordance between pre- and postoperative assessments of primary caries lesion depths by dentists from The Dental Practice-Based Research Network (DPBRN; www.DentalPBRN.org). A total of 229 DPBRN dentists collected data on 8,351 consecutive restorations inserted due to primary caries in 5,810 patients. Dentists estimated the preoperative depth of caries lesions based on the diagnostic methods they typically used. The preoperative depth was then compared to the postoperative depth, which dentists determined using actual clinical observation. Both estimated and observed depths were recorded as being in the outer half (E1) or inner half (E2) of enamel, or in the outer third (D1), middle third (D2) or inner third (D3) of dentin. Most restorations were placed to treat lesions that were preoperatively assessed as extending to the D1 (53%) and D2 (25%) depths. Of the restored caries lesions, 10% were preoperatively assessed as being limited to E2 depth and 3% to E1 depth. The majority of the restored enamel lesions were located on occlusal surfaces. Preoperative estimates of caries lesion depth were more concordant with postoperative depths when the lesion was at an advanced stage: 88% concordance at the D3 depth, compared to 54% concordance at the E1 depth. DPBRN dentists can discriminate caries lesions at different depths, but the accuracy of their depth assessments was higher for dentin than for enamel lesions. In general, DPBRN dentists were more likely to underestimate than overestimate the depth of caries lesions, and the extent of underestimation was greater for enamel than for dentin lesions.

Prenatal smoking and the risk of early childhood caries: A prospective cohort study.

INTRODUCTION: Dental caries is a chronic complex disease of multifactorial etiology that affects a quarter of U.S. children. This study evaluated the association between prenatal smoking and offspring caries experience and used a negative control exposure analysis to assess if the association is causal. METHODS: Data from 1429 mother-offspring participants of the 1991/92 Avon Longitudinal Study of Parents and Children conducted in Bristol, England were analyzed. Prenatal smoking (yes v. no) and quantity smoked (none,

Accuracy of Maternal Reports of Young Children's Dental Disease Status: Avon Longitudinal Study of Parents and Children.

Background: Parental reports of their children's health status is integral to pediatric medical and dental care. Therefore, understanding the accuracy of such reports is vital. Our objectives were to (1) assess the correlation between maternal reports of their children's indicators of caries experience (subjective assessment) and actual caries status determined by oral examination (objective assessment), and (2) identify potential modifiers of this correlation. Methods: Longitudinal data from the Avon longitudinal study of parents and children (n = 1429) was used to assess the correlation between maternal reports of the number of missing and filled teeth of children aged 38 months, 54 months, and 5.5 years and clinical oral examinations of decayed, missing and filled teeth conducted when the same children were 31, 43 months, and five years of age. Homogeneity chi-square tests assessed differences in correlations according to sociodemographic factors. Results: Overall, we found a statistically significant correlation that was weak to moderate in magnitude. Maternal reports of missing teeth at 38 months was significantly correlated with decayed teeth, 0.27 (p < 0.001); missing teeth, 0.23 (p < 0.001), and the decayed, missing and filled (dmft) index, 0.35 (p < 0.001) based on oral examination at 31 months. A maternal report of filled teeth at 54 months was significantly correlated with decayed teeth, 0.30 (p < 0.001); filled teeth 0.30 (p < 0.001), and dmft 0.40 (p < 0.001) at 43 months. Mothers tended to underestimate the extent of missing and filled teeth in their children irrespective of the child's age, but the extent of underestimation was greater among younger children. Maternal age, education level, and whether the child had ever visited a dentist were significant modifiers of subjective and objective caries assessments. Conclusions: From a clinical and dental public health perspective, our findings of a weak to moderate correlation of maternal assessments of their children's caries experience may be concerning when reporting the burden of dental diseases in large population studies or for surveillance purposes that rely on self-reported measures and must therefore be utilized with caution because of the potential to result in underestimated disease burden.

Approaches to Modulate Biofilm Ecology.

Dental caries is closely related to a dysbiosis of the microbial consortia of supragingival oral biofilms driven by a sugar-frequent and acidic-pH environment. The pH is a key factor affecting the homeostasis of supragingival biofilms seen in health. There is increasing interest on the ecological dynamics of the oral microbiome and how a dysbiotic microbiota can be successfully replaced by health-beneficial flora. The concept of preventing the microbial dysbiosis related to caries through modulation of sugar intake and pH has fully emerged.

Global regulation by (p)ppGpp and CodY in Streptococcus mutans.

The RelA, RelP, and RelQ enzymes are responsible for the production of the alarmone (p)ppGpp in Streptococcus mutans. A strain lacking all three synthetases (DeltarelAPQ) does not grow in minimal medium lacking the branched-chain amino acids (BCAA) leucine or valine but grows well if isoleucine is also omitted. Here, we investigated whether there was a correlation between growth in the absence of leucine and valine with (p)ppGpp pools and the activation of CodY. By using a combination of single, double, and triple mutants lacking the (p)ppGpp synthetase enzymes, we demonstrated that the ability to grow in the absence of leucine or valine required basal levels of (p)ppGpp production by RelP and RelQ. The introduction of a codY mutation into the DeltarelAPQ strain fully restored growth in medium lacking leucine or valine, revealing that the growth-defective phenotype of DeltarelAPQ was directly linked to CodY. Lowering GTP levels through the addition of decoyinine did not alleviate CodY repression or affect the expression of genes involved in BCAA biosynthesis, suggesting that S. mutans CodY is not activated by GTP. The results of phenotypic studies revealed that the codY mutant had a reduced capacity to form biofilms and that its growth was more sensitive to low pH, showing a role for CodY in two key virulence properties of S. mutans. Microarray results revealed the extent of the CodY regulon. Notably, the identification of putative CodY-binding boxes upstream of genes that were downregulated in the codY mutant indicates that CodY may also function as a transcriptional activator in S. mutans.