Background The action mechanism of silver diammine fluoride (SDF) on plaque micro-ecology was seldom studied. This study investigated micro-ecological changes in dental plaque on extensive carious cavity of deciduous teeth after topical SDF treatment. Methods Deciduous teeth with extensive caries freshly removed from school children were collected in clinic. After initial plaque collection, each cavity was topically treated with 38% SDF in vitro. Repeated plaque collections were done at 24 hours and 1 week post-intervention. Post-intervention micro-ecological changes including microbial diversity, microbial metabolism function as well as inter-microbial connections were analyzed and compared after Pyrosequencing of the DNA from the plaque sample using Illumina MiSeq platform. Results After SDF application, microbial diversity decreased (p>0.05). Microbial community composition post-intervention was obviously different from that of supragingival and pre-intervention plaque as well as saliva. At 1 week post-intervention, the relative content of Pseudomonas , Fusobacterium and Pseudoramibacter was obviously higher than before, while most of the other bacteria was obviously reduced, although not statistically significant (P>0.05). The inter-microbial connections became more complex, with positive connections overcame negative ones. Carbohydrate transportation and metabolic functions in the plaque were significantly reduced at 24 hours and 1 week post-intervention. Conclusions SDF has extensive antimicrobial effect on dental plaque, which may reduce carbohydrate metabolism in dental plaque and help promote new balance of the plaque flora.

Background: The mechanism of action of silver diammine fluoride (SDF) on plaque micro-ecology is seldom studied. This study investigated micro-ecological changes in dental plaque on extensive caries of deciduous teeth after topical SDF treatment. Methods: Deciduous teeth with extensive caries freshly removed from school children were collected in clinic. Unstimulated saliva collection and initial plaque sampling were done before tooth extraction, then each caries was topically treated with 38% SDF in vitro. After intervention, each tooth was stored respectively in artificial saliva at 37℃. Repeated plaque collections were done at 24 hours and 1 week post-intervention. Post-intervention micro-ecological changes including microbial diversity, microbial metabolism function as well as species correlations were analyzed and compared after pyrosequencing of the DNA from the plaque sample using Illumina MiSeq platform. Results: After SDF application, microbial diversity decreased (P>0.05), although not statistically significant. Microbial community composition post-intervention was noticeably different from that of supragingival and pre-intervention plaque as well as saliva. At 1 week post-intervention, the relative content of Pseudomonas, Fusobacterium and Pseudoramibacter was noticeably higher than before, while most of the other bacteria was noticeably reduced, although not statistically significant (P>0.05). The inter-microbial associations became more complex, much more positive associations among survived bacteria were observed than negative ones. COG function classification diagram showed carbohydrate transportation and metabolic functions in the plaque were significantly reduced at 24 hours and 1 week post-intervention. Conclusions: SDF has extensive antimicrobial effect on dental plaque, which may reduce carbohydrate metabolism in dental plaque and help promote new balance of the plaque flora.

Background The mechanism of action of silver diammine fluoride (SDF) on plaque micro-ecology is seldom studied. This study investigated micro-ecological changes in dental plaque on extensive caries of deciduous teeth after topical SDF treatment. Methods Deciduous teeth with extensive caries freshly removed from school children were collected in clinic. Unstimulated saliva collection and initial plaque sampling were done before tooth extraction, then each caries was topically treated with 38% SDF in vitro. After intervention, each tooth was stored respectively in artificial saliva at 37°C. Repeated plaque collections were done at 24 hours and 1 week post-intervention. Post-intervention micro-ecological changes including microbial diversity, microbial metabolism function as well as species correlations were analyzed and compared after pyrosequencing of the DNA from the plaque sample using Illumina MiSeq platform. Results After SDF application, microbial diversity decreased (p>0.05), although not statistically significant. Microbial community composition post-intervention was noticeably different from that of supragingival and pre-intervention plaque as well as saliva. At 1 week post-intervention, the relative content of Pseudomonas , Fusobacterium and Pseudoramibacter was noticeably higher than before, while most of the other bacteria was noticeably reduced, although not statistically significant (P>0.05). The inter-microbial associations became more complex, much more positive associations among survived bacteria were observed than negative ones. COG function classification diagram showed carbohydrate transportation and metabolic functions in the plaque were significantly reduced at 24 hours and 1 week post-intervention. Conclusions SDF has extensive antimicrobial effect on dental plaque, which may reduce carbohydrate metabolism in dental plaque and help promote new balance of the plaque flora.