SRP313080 PRJNA712952 Functional changes in the oral microbiome after use of fluoride and arginine dentifrices: a metagenomic and metatranscriptomic study Tooth decay is one of the most prevalent diseases worldwide and efficient tooth brushing with a fluoride containing dentifrice is considered fundamental to prevent caries initiation. Fluoride-containing dentifrices have been extensively studied in relation to enamel resistance to demineralization, but its effect on the oral microbiota is less understood. Arginine has also been proposed as a promising prebiotic to promote pH buffering through ammonia production. Here, we present the first metagenomic (DNA sequencing of the whole microbial community) and metatranscriptomic (RNAseq of the same community) analyses of human dental plaque that evaluate the effect of a fluoride and a Fl+Arg dentifrices on oral microbial composition and activity. Fifty-three patients were enrolled in a clinical intervention study, including 26 caries-active and 27 caries-free adults. After a minimum 1-week washout period, dental plaque samples were collected at this post-washout baseline, 3 months after the use of a 1,450 ppm fluoride dentifrice and after 6 months of using a 1,450 ppm fluoride with 1.5% arginine dentifrice. Homo sapiens oral sample