Deep metagenomics examines the oral microbiome during dental caries, revealing novel taxa and co-occurrences with host molecules.

Dental caries, the most common chronic infectious disease worldwide, has a complex etiology involving the interplay of microbial and host factors that are not completely understood. In this study, the oral microbiome and 38 host cytokines and chemokines were analyzed across 23 children with caries and 24 children with healthy dentition. De novo assembly of metagenomic sequencing obtained 527 metagenome-assembled genomes (MAGs), representing 150 bacterial species. Forty-two of these species had no genomes in public repositories, thereby representing novel taxa. These new genomes greatly expanded the known pangenomes of many oral clades, including the enigmatic Saccharibacteria clades G3 and G6, which had distinct functional repertoires compared to other oral Saccharibacteria. Saccharibacteria are understood to be obligate epibionts, which are dependent on host bacteria. These data suggest that the various Saccharibacteria clades may rely on their hosts for highly distinct metabolic requirements, which would have significant evolutionary and ecological implications. Across the study group, Rothia, Neisseria, and Haemophilus spp. were associated with good dental health, whereas Prevotella spp., Streptococcus mutans, and Human herpesvirus 4 (Epstein-Barr virus [EBV]) were more prevalent in children with caries. Finally, 10 of the host immunological markers were significantly elevated in the caries group, and co-occurrence analysis provided an atlas of potential relationships between microbes and host immunological molecules. Overall, this study illustrated the oral microbiome at an unprecedented resolution and contributed several leads for further study that will increase the understanding of caries pathogenesis and guide therapeutic development.

A national sample of developmentally disabled adolescents with obesity and their utilization of preventive dental care services.

Background: Previous literature indicates that adolescents with developmental disabilities and obesity may have more oral health complications than healthy adolescents. However, dental care utilization among adolescents with developmental disabilities (DDs) and obesity is unclear. We investigated the differences in the utilization of preventive dental services between this high-risk group of adolescents and those with no DDs or obesity. Methods: Parent-reported data of adolescents 10-17 years (n = 68,942) from the 2016 to 2019 National Survey of Children's Health was used. In addition to descriptive and bivariate statistics, we ran three multiple logistic regression models guided by Andersen's Behavioral Model of Health Services Use, predicting the use of dental cleanings, fluoride treatments, and dental sealants. Results: Among adolescents with DDs and obesity, dental cleanings, fluoride treatments, and dental sealant utilization prevalence were 76%, 48%, and 21%, respectively. In comparison, adolescents with no DDs or obesity had a prevalence of 83%, 50%, and 19%, respectively. Multiple logistic regression analysis showed that adolescents with DDs and obesity did not significantly differ in their receipt of dental cleanings (p = .07), fluoride treatments (p = .55), and dental sealants (p = .23) compared to those with neither DDs nor obesity. Adolescents with DDs but no obesity were 22% and 30% more likely to receive fluoride treatments (p < .0001) and dental sealants (p < .0001), respectively. Conclusions: Fewer than half of adolescents with DDs and obesity utilized fluoride treatments, and less than one quarter utilized dental sealants but used all three preventive services at the same rate as those with no DDs or obesity. Implications: This study identified no differences in preventive dental care services utilization in adolescents with developmental disabilities (DDs) and obesity compared to those without DDs and obesity. However, the utilization of preventive dental services in this population is influenced by the federal poverty level and family background.

Correlation between Streptococcus mutans levels in dental plaque and saliva of children.

PURPOSE: This study was designed to compare the levels of Streptococcus mutans (S. mutans) in saliva with those in occlusal plaque on posterior teeth at different stages of dentition, and to explore the correlation with caries experience to determine the most suitable source of S. mutans for research. METHODS: Samples of saliva and occlusal plaque were collected from 83 patients (aged 3-17 years) over three months. S. mutans levels were determined by culture-based selective plating, morphological identification, and S.mutans-specific monoclonal antibody labeling. RESULTS: The mean age of the participants was 8.8 (±3.7) years, and 74.7% of them were Hispanic. Mean caries experience for children with primary, mixed, and permanent dentition was 5.2 (±4.7), 4.0 (±3.3), and 0.8 (±1.3), respectively. Children with primary and mixed dentition had a higher caries experience than children with permanent dentition (P < 0.01), despite having similar S. mutans levels and total bacteria. A positive correlation was observed between S. mutans levels in plaque and those in saliva, but not between S. mutans levels and caries experience. It was noteworthy that plaque samples harbored higher S. mutans levels (>105 CFU/mL) than saliva samples. CONCLUSION: Both plaque and saliva samples are useful sources for S. mutans isolation. S. mutans levels from both sources were not significantly correlated with caries experience, but occlusal plaque had greater sensitivity for quantification of high S. mutans levels.

Effectiveness of the GumChucks flossing system compared to string floss for interdental plaque removal in children: a randomized clinical trial.

Flossing, an important oral hygiene skill, is technique-sensitive and challenging for children with developing manual dexterity. GumChucks is a novel flossing device designed to assist children with proper flossing technique. The aim of this study was to assess the efficacy of the GumChucks flossing device compared to string floss (SF). We conducted a randomized trial with 40 children aged 4-15 years at the UCLA Children's Dental Center from January- April 2017. Participants were randomly assigned to either GumChucks or SF. Interdental plaque score (IPS) and gingival index (GI) were recorded at baseline and 4-week post-usage. Flossing speed and interdental plaque reduction were also determined immediately after first use. In addition, questionnaires were completed by children, parents and dentists. Overall, children flossed significantly faster (p < 0.001) and achieved greater IPS reduction after first use (47.0% vs. 26.8%) with GumChucks compared to SF. After 4-week post-usage, children ages 10-15 in the GumChucks group demonstrated significantly greater improvement in GI and IPS from baseline (p < 0.01) and greater efficacy in interdental plaque removal compared to the SF group (p < 0.01). Children ages 4-9 flossed more effectively (p < 0.01) with GumChucks after first use, but no significant IPS and GI improvement after 4-week post-usage. Children preferred GumChucks (92.5%) over SF, with a similar positive attitude reported by parents and dentists. GumChucks is an effective alternative interdental plaque removal aid that allows children to floss with greater speed and efficacy, with recommended parental supervision for children under age 10.

Identification of the Bacterial Biosynthetic Gene Clusters of the Oral Microbiome Illuminates the Unexplored Social Language of Bacteria during Health and Disease.

Small molecules are the primary communication media of the microbial world. Recent bioinformatic studies, exploring the biosynthetic gene clusters (BGCs) which produce many small molecules, have highlighted the incredible biochemical potential of the signaling molecules encoded by the human microbiome. Thus far, most research efforts have focused on understanding the social language of the gut microbiome, leaving crucial signaling molecules produced by oral bacteria and their connection to health versus disease in need of investigation. In this study, a total of 4,915 BGCs were identified across 461 genomes representing a broad taxonomic diversity of oral bacteria. Sequence similarity networking provided a putative product class for more than 100 unclassified novel BGCs. The newly identified BGCs were cross-referenced against 254 metagenomes and metatranscriptomes derived from individuals either with good oral health or with dental caries or periodontitis. This analysis revealed 2,473 BGCs, which were differentially represented across the oral microbiomes associated with health versus disease. Coabundance network analysis identified numerous inverse correlations between BGCs and specific oral taxa. These correlations were present in healthy individuals but greatly reduced in individuals with dental caries, which may suggest a defect in colonization resistance. Finally, corroborating mass spectrometry identified several compounds with homology to products of the predicted BGC classes. Together, these findings greatly expand the number of known biosynthetic pathways present in the oral microbiome and provide an atlas for experimental characterization of these abundant, yet poorly understood, molecules and socio-chemical relationships, which impact the development of caries and periodontitis, two of the world's most common chronic diseases.IMPORTANCE The healthy oral microbiome is symbiotic with the human host, importantly providing colonization resistance against potential pathogens. Dental caries and periodontitis are two of the world's most common and costly chronic infectious diseases and are caused by a localized dysbiosis of the oral microbiome. Bacterially produced small molecules, often encoded by BGCs, are the primary communication media of bacterial communities and play a crucial, yet largely unknown, role in the transition from health to dysbiosis. This study provides a comprehensive mapping of the BGC repertoire of the human oral microbiome and identifies major differences in health compared to disease. Furthermore, BGC representation and expression is linked to the abundance of particular oral bacterial taxa in health versus dental caries and periodontitis. Overall, this study provides a significant insight into the chemical communication network of the healthy oral microbiome and how it devolves in the case of two prominent diseases.