<i>Streptococcus dentisani</i> as an oral probiotic: a systematic review of clinical evidence on the pH modulation and microbiota shifts.

Abstract

<h4>Background</h4>Dental caries prevention can be approached through ecological modulation of the oral biofilm. Among oral probiotics, <i>Streptococcus dentisani</i> stands out for its arginine deiminase (ADI) pathway, producing ammonia with an alkalinizing effect, and for bacteriocins active against cariogenic organisms, suggesting restoration of acid-base homeostasis and displacement of dysbiosis-associated taxa.<h4>Objective</h4>To systematically review clinical evidence on <i>S. dentisani</i> and other probiotics regarding their effects on pH modulation and oral microbiota shifts.<h4>Methods</h4>A PRISMA-guided systematic review of PubMed, Scopus, and Web of Science was conducted, including randomized controlled trials (RCTs) and observational studies reporting at least one prespecified outcome (pH or microbiota).<h4>Results</h4>Two clinical studies specifically assessed S. dentisani, reporting transient oral colonization, increased salivary alkalinity, and reductions in <i>S. mutans</i>, with one trial documenting a favorable community shift by 16S sequencing. Across the remaining studies, which mainly involved <i>Lactobacillus</i> and <i>Bifidobacterium</i> strains, nine reported reductions in cariogenic markers and five reported increases in pH/buffering capacity; these findings do not pertain to <i>S. dentisani</i> but to other probiotic strains. Caries incidence was evaluated only in lactic probiotic trials with mixed findings; no caries-incidence data were available for <i>S. dentisani</i>.<h4>Conclusions</h4><i>S. dentisani</i> demonstrates consistent mechanistic benefits-pH increase and modulation of the oral microbiota-supporting its candidacy as an oral probiotic. Evidence on caries prevention remains insufficient, underscoring the need for longer, standardized trials incorporating clinical endpoints and microbiological profiling.