Comparison of initial oral microbiomes of young adults with and without cavitated dentin caries lesions using an in situ biofilm model

Abstract

Dental caries is caused by acids released from bacterial biofilms. However, the in vivo formation of initial biofilms in relation to caries remains largely unexplored. The aim of this study was to compare the oral microbiome during the initial phase of bacterial colonization for individuals with (CC) and without (NC) cavitated dentin caries lesions. Bovine enamel slabs on acrylic splints were worn by the volunteers (CC: 14, NC: 13) for in situ biofilm formation (2 h, 4 h, 8 h, 1 ml saliva as reference). Sequencing of the V1/V2 regions of the 16S rRNA gene was performed (MiSeq). The relative abundances of individual operational taxonomic units (OTUs) were compared between samples from the CC group and the NC group. Random forests models were furthermore trained to separate the groups. While the overall heterogeneity did not differ substantially between CC and NC individuals, several individual OTUs were found to have significantly different relative abundances. For the 8 h samples, most of the significant OTUs showed higher relative abundances in the CC group, while the majority of significant OTUs in the saliva samples were more abundant in the NC group. Furthermore, using OTU signatures enabled a separation between both groups, with area-under-the-curve (AUC) values of ~0.8. In summary, the results suggest that initial oral biofilms provide the potential to differentiate between CC and NC individuals.

Relationship between dental and periodontal health status and the salivary microbiome: bacterial diversity, co-occurrence networks and predictive models

“…As findings derived from these studies, the saliva samples from the healthy and caries groups generally had similar levels of richness and diversity 25 , 68 – 70 . This was true whether the diseased group was composed of subjects with active 68 , inactive 69 or cavitated 70 caries. In the present series, the salivary microbiota of those with the highest dental pathology grades (DG23) was significantly richer in bacteria than that of those who had a healthy dental grade (DG0); DG23 also showed a trend towards increased diversity and evenness.…”

“…Various 16S-based microbiome studies on the impact of dental decay on the salivary microbiota of adults have used the DMFT index to place individuals in a healthy or a caries group 25 , 68 , 69 , with the latter including subjects with active caries (DMFT ≥ 6) 68 or inactive tooth decay 69 . In their study, Rupf et al 70 used the Nyvad criteria to define caries activity and recruit patients for their sample who had at least three caries lesions that reached the dentine; they also used the DMFT Index and the ICDAS 70 .…”

“…Numerous 16S-based microbiome studies on salivary microbiota in the literature have only conducted an analysis of the differential abundance of the taxa associated with various oral conditions 26 , 29 , 70 , 80 . In this study, it is our view that it is essential to analyse salivary microbiota from a dual perspective: the prevalence of the taxa determining the core microbiome; and their differential abundance in relation to the different DGs, PGs and OGs.…”

“…vicentii . Even, some authors have demonstrated that different strains of the same species of Veillonella parvula had different implications for oral health or disease 68 , 70 . This would justify the claim of Callahan et al 83 concerning the biological importance of conducting 16S rRNA gene-based analyses at the bacterial variant level.…”

Amplicon-based microbiome study highlights the loss of diversity and the establishment of a set of species in patients with dentin caries

“…Microbiome analysis using Next Generation Sequencing (NGS) technology can unravel complex compositions of oral biofilms and so far helps finding non-culturable and “overlooked” bacteria [1–5]. Having insight into biofilm compositions at different sites and under various environmental or pathologic conditions is mandatory for further understanding of this extremely complex eco-system.…”