# Effects of silver diamine fluoride on oral bacteriome and mycobiome: a randomized clinical trial

## TL;DR

This study shows that silver diamine fluoride with sodium fluoride varnish effectively arrests early childhood caries while altering the abundance of specific oral bacteria and fungi.

## Contribution

The study provides empirical evidence on the effects of SDF treatment frequency on ECC arrest rates and oral microbiome composition.

## Key findings

- SDF with NaF varnish achieved 92.8% caries arrest after two applications.
- Treatment frequency influenced arrest rates, with one-month and four-month intervals showing higher efficacy.
- SDF altered the abundance of Lactobacillus, Bifidobacterium, and Candida species without reducing overall microbial diversity.

## Abstract

Silver diamine fluoride (SDF) is a simple and non-invasive agent used to arrest early childhood caries (ECC). This study aimed to investigate potential changes to the oral microbiome in children with ECC who were treated with SDF and sodium fluoride (NaF) varnish at three different frequency regimens.

Forty-five children (n = 15 per group) with ECC were recruited from community-based dental clinics in Winnipeg, Canada into an open-label, parallel-group, randomized clinical trial testing three different treatment frequency regimens of SDF. A total of 195 carious lesions were treated with two applications of 38% SDF and 5% NaF varnish (and assessed over three study visits one month, four months, or six months apart. Dental plaque samples were collected at each visit. Sequencing of the V4-16 S rRNA and ITS1 rRNA genes were used to study the supragingival plaque microbiome.

Microbial diversity analyses showed no significant differences in the overall microbiome after SDF treatment. However, significant changes in the abundance of specific bacteria and fungi, particularly Lactobacillus spp., Bifidobacterium spp., and Candida spp., were observed after treatment. Furthermore, overabundance of Streptococcus mutans and Candida dubliniensis at baseline was observed in children who had at least one caries lesion not arrested after one SDF application, compared to those who had 100% arrest rates. The overall arrest rates for treated carious lesions were 75.9% at the second visit and 92.8% at the third visit. Arrest rates were higher for all lesions after two applications of SDF with NaF varnish, and applications one month and four months apart had higher arrest rates (95.9% and 98.5%) than six months (81.1%) apart.

Applications of SDF with NaF varnish were an effective modality for arresting ECC, with higher arrest rates after two SDF applications. No loss of diversity but changes in the abundance of specific bacteria and fungi were observed after SDF treatment.

ClinicalTrials.gove NCT04054635 (first registered 13/08/2019).

The online version contains supplementary material available at 10.1186/s12903-025-06986-0.