Abstract
Methods The present study aimed to identify patterns and processes in acquisition of oral bacteria and to characterize the microbiota of different dentition states and habitats. Mucosal, salivary, supragingival, and subgingival biofilm samples were collected from orally and systemically healthy children and mother-child dyads in predentate, primary, mixed, and permanent dentitions. 16S rRNA gene sequences were compared to the Human Oral Microbiome Database (HOMD). Functional potential was inferred using PICRUSt.ResultsUnweighted and weighted UniFrac distances were significantly smaller between each mother-predentate dyad than infant-unrelated female dyads. Predentate children shared a median of 85% of species-level operational taxonomic units (s-OTUs) and 100% of core s-OTUs with their mothers. Maternal smoking, but not gender, mode of delivery, feeding habits, or type of food discriminated between predentate microbial profiles. The primary dentition demonstrated expanded community membership, structure, and function when compared to the predentate stage, as well as significantly lower similarity between mother-child dyads. The primary dentition also included 85% of predentate core s-OTUs. Subsequent dentitions exhibited over 90% similarity to the primary dentition in phylogenetic and functional structure. Species from the predentate mucosa as well as new microbial assemblages were identified in the primary supragingival and subgingival microbiomes. All individuals shared 65% of species between supragingival and subgingival habitats; however, the salivary microbiome exhibited less than 35% similarity to either habitat.ConclusionsWithin the limitations of a cross-sectional study design, we identified two definitive stages in oral bacterial colonization: an early predentate imprinting and a second wave with the eruption of primary teeth. Bacterial acquisition in the oral microbiome is influenced by the maternal microbiome. Personalization begins with the eruption of primary teeth; however, this is limited to phylogeny; functionally, individuals exhibit few differences, suggesting that microbial assembly may follow a defined schematic that is driven by the functional requirements of the ecosystem. This early microbiome forms the foundation upon which newer communities develop as more colonization niches emerge, and expansion of biodiversity is attributable to both introduction of new species and increase in abundance of predentate organisms.
Highlights
The oral cavity is one of most microbe-rich environments in the human body, at birth, most children do not possess a colonized microbiome [1,2,3]
The eruption of primary teeth creates two more niches for bacterial colonization, a supragingival habitat consisting of a non-shedding enamel tooth surface and a subgingival habitat composed of an abiotic tooth surface, the junctional epithelium and the epithelial lining of the gingival sulcus
Acquisition of oral bacteria The predentate community We examined acquisition of oral bacteria by first establishing a microbial catalogue from 1.4 million sequences from all 47 predentate mucosal samples
Summary
The oral cavity is one of most microbe-rich environments in the human body, at birth, most children do not possess a colonized microbiome [1,2,3]. Upon exposure to the environment during and following the birthing process, colonization of the oral cavity occurs within 8–16 h [3]. In the absence of natal teeth, the mucosal surfaces lining the oral cavity provide the only environment for bacterial colonization. 6 years following the establishment of this stable dentate environment, the primary dentition begins to exfoliate, giving way to the permanent dentition. This approximately 6-year phase when an individual has a mixture of teeth from both the primary and permanent dentitions is termed the mixed dentition, following which an adult permanent dentition is established. In order to understand the role of the microbiome in the predisposition to, or in prevention of, disease, it is essential to define the development of microbial assemblages in this ecosystem and the partitioning that occurs with the introduction of new colonization niches
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