Plaque biofilm microbial diversity in infants aged 12 months and their mothers with or without dental caries: a pilot study

Background: A number of studies on oral microbial diversity of early childhood caries (ECC) have tended to focus on mid- or late-stage of ECC, with a lack of research into early stage of tooth eruption and maternal influence. The aims of this study are to compare the supragingival plaque biofilm microbiota diversity between mothers with or without dental caries and their 12-month-old infants, and to explore the relationship of microbial diversity between infants and their mothers, using sequencing analysis.

Methods: Supragingival plaque biofilm samples were collected from 20 pairs of mothers and their infants aged 12 months (10 mothers with dental caries and their 10 infants vs. 10 caries-free mothers and their 10 infants). The basic information of the mothers and infants had been collected through self-completed questionnaire. Pooled plaque biofilm DNA was extracted and DNA amplicons of the V4-V5 hypervariable region of the bacterial 16S rRNA gene were generated. Ilumina Miseq PE300 was used for 16S rRNA sequencing.

Results: The results showed that high bacterial diversity was noted in the plaque biofilm of infants and their mothers with or without dental caries (dental caries mothers vs. caries-free mothers: 774 operational taxonomical units (OTUs) vs. 761 OTUs at a 3% divergence; infants whose mothers have dental caries vs. infants whose mothers are caries-free: 815 OTUs vs. 684 OTUs at 3% divergence). The Shannon microbial diversity index showed no statistically significant differences both on infants and their mothers between two groups (p > 0.05). Mother's microbial diversity was higher than infants' based on Shannon index (p < 0.05). Significant positive correlations were found between mothers' and their infants' Shannon index (r = 0.656, p = 0.002).

Conclusion: Oral microbial diversity is significantly different between mothers and infants regardless of dental caries status, but no significant difference was found between mothers with and without dental caries or between their infants. Mother's oral microbial diversity has an overall impact on the infants aged 12 months.