Structural and Functional Characteristics of the Microbiome in Deep-Dentin Caries

Area of Science:

• Microbiology
• Genomics
• Dentistry

Background:

• Dental caries is a dynamic disease driven by cariogenic bacteria and fermentable carbohydrates.
• The new ecological hypothesis highlights microbial community alterations and metabolic genes in caries initiation and progression.

Purpose of the Study:

• To determine the structural and functional characteristics of microbial communities in human deep-dentin carious lesions.
• To analyze microbial composition and abundance at multiple taxonomic levels.
• To investigate functional pathways associated with caries using metagenomic sequencing.

Main Methods:

• Collected 16 deep-dentin carious lesions from permanent molars of 8 patients (aged 9-18).
• Utilized shotgun metagenomic sequencing for microbial composition and abundance analysis.
• Performed functional analysis using DIAMOND software against the Kyoto Encyclopedia of Genes and Genomes (KEGG) database.

Main Results:

• Actinobacteria (35.8%) and Firmicutes (31.2%) were the most prevalent phyla.
• Microbial composition varied individually, with no significant differences between superficial and deep lesion layers.
• Abundant genera included Actinomyces (10.5%), Olsenella (9.4%), and Prevotella (8.8%), with Lactobacillus present in only 25% of samples.
• Metabolic pathways, particularly carbohydrate metabolism, were the most abundant functional traits.

Conclusions:

• Deep-dentin carious lesions harbor a complex microbial community dominated by Actinobacteria and Firmicutes.
• The functional profile is characterized by active carbohydrate and amino acid metabolism.
• Microbial community interactions are fundamental to the etiology of dental caries.