Exploring the oral microbiota of children at various developmental stages of their dentition in the relation to their oral health

Pyrosequencing reads (126174 reads, 1045 unique sequences) represented 8 phyla and 113 higher taxa in saliva samples. Four phyla - Firmicutes, Bacteriodetes, Proteobacteria and Actinobacteria - predominated in all groups. The deciduous dentition harboured a higher proportion of Proteobacteria (Gammaproteobacteria, Moraxellaceae) than Bacteroidetes, while in all other groups Bacteroidetes were at least as abundant as Proteobacteria. Bacteroidetes (mainly genus Prevotella), Veillonellaceae family, Spirochaetes and candidate division TM7 increased with increasing age, reflecting maturation of the microbiome driven by biological changes with age.Microarray analysis enabled further analysis of the individual salivary microbiota. Of 350 microarray probes, 156 gave a positive signal with, on average, 77 (range 48-93) probes per individual sample.A caries-free oral status significantly associated with the higher signal of the probes targeting Porphyromonas catoniae and Neisseria flavescens.The potential role of P. catoniae and N. flavescens as oral health markers should be assessed in large-scale clinical studies. The combination of both, open-ended and targeted molecular approaches provides us with information that will increase our understanding of the interplay between the human host and its microbiome.The oral cavity is a complex ecological niche, as is reflected by its complex microbial community. Recent advances in sequencing technology, such as 454 pyrosequencing, have revealed an unexpectedly high diversity of the human oral microbiome: dental plaque pooled from 98 healthy adults comprised about 10000 microbial phylotypes [1]. This is an order of magnitude higher than previously reported 700 oral microbial phylotypes as identified by cultivation or traditional cloning and sequencing [2].Studies have revealed that the various sites in the oral cavity, such as the hard dental surfaces, mucosal sites, and anaerobic pockets, house unique microbial communities [3,4]. The