Silver diamine fluoride alters microbial communities in subsurface dentin

Background

Silver diamine fluoride (SDF) is a dental biomaterial with cariostatic properties that are thought to be owing to, in part, to its antimicrobial activity. This study examines the mechanisms by which SDF may impact the oral microbiota.

Methods

This case-control study uses samples from carious lesions of primary teeth with or without SDF treatment; the authors used microbial viability testing and next-generation sequencing to compare untreated or SDF-treated carious surface biofilm and subsurface carious dentin.

Results

Viability testing of surface biofilm from carious lesions with or without SDF treatment visualized by confocal laser scanning microscopy revealed no change in microbial viability several weeks after SDF treatment. Microbial community composition of carious surface biofilm before and after SDF treatment was determined using 16S rRNA gene sequencing. Comparison of the microbiota by permutational multivariate analysis of variance revealed no significant difference between the carious surface biofilm before and after SDF treatment. To examine for changes in subsurface bacteria in the setting of SDF treatment, excavated subsurface carious dentin from untreated or SDF-treated carious lesions were profiled using 16S rRNA gene sequencing and compared with permutational multivariate analysis of variance, which revealed a significant difference between SDF-treated and untreated lesions (P =.006). The mean abundance of 15 species was significantly different between no SDF and SDF-treated subsurface carious dentin samples on the basis of negative binomial regression analysis.

Conclusions

Although SDF does not significantly alter the carious surface biofilm microbial community composition, it promotes a shift in community membership deeper within dentin tubules, representing a previously unrecognized mechanism of action for SDF in caries arrest.