Microbial Complexes and Caries in 17-Year-Olds with and without Streptococcus mutans

Area of Science:

• Oral microbiology
• Dental caries research
• Microbiome analysis

Background:

• Streptococcus mutans is a primary driver of dental caries, affecting over 90% of the global population.
• However, other acidogenic and acid-tolerant bacteria can also contribute to caries development.
• In low-caries populations like Sweden, caries-affected adolescents often lack detectable S. mutans.

Purpose of the Study:

• To characterize the tooth biofilm and saliva microbiota in adolescents with caries, with or without detectable S. mutans.
• To identify bacterial taxa clustering in oral samples and correlate these clusters with caries status.
• To investigate the role of specific bacterial species in different caries profiles.

Main Methods:

• Analysis of tooth biofilm and saliva samples from 154 17-year-olds using multiplex 16S rDNA (V3-V4) sequencing.
• Utilized the Human Oral Microbiome Database and ProbeSeq pipeline for Next-Generation Sequencing (NGS) analysis.
• Recorded enamel and dentin caries, caries experience, and collected lifestyle data.

Main Results:

• In subjects with caries experience, high S. mutans levels correlated with a few species, while low levels were associated with saccharolytic species.
• Present caries in S. mutans-negative subjects was linked to a panel of saccharolytic species.
• Four distinct clusters of subjects based on caries experience were identified using tooth biofilm microbiota data.
• Multivariate modeling indicated S. mutans and Scardovia wiggsiae were influential in high S. mutans caries, while other lactic acid producers were key in S. mutans-free subjects.

Conclusions:

• Findings support a significant role for S. mutans in caries among infected adolescents.
• The ecological concept of caries is supported, particularly in S. mutans-free individuals.
• Specific bacterial panels, including S. mutans, Scardovia wiggsiae, and other saccharolytic species, are associated with distinct caries profiles in adolescents.