ABSTRACTBackgroundDental caries is a chronic, multifactorial and biofilm-mediated oral bacterial infection affecting almost every age group and every geographical region.Streptococcus mutansis considered an important pathogen responsible for the initiation and development of dental caries. It produces exopolysaccharidesin situto promote the colonization of cariogenic bacteria and coordinate dental biofilm development.ObjectiveThe understanding of the regulatory mechanism ofS. mutansbiofilm formation can provide a theoretical basis for the prevention and treatment of caries.DesignAt present, an increasing number of studies have identified many regulatory systems inS. mutansthat regulate biofilm formation, including second messengers (e.g. c-di-AMP, Ap4A), transcription factors (e.g. EpsR, RcrR, StsR, AhrC, FruR), two-component systems (e.g. CovR, VicR), small RNA (including sRNA0426, srn92532, and srn133489), acetylation modifications (e.g. ActG), CRISPR-associated proteins (e.g. Cas3), PTS systems (e.g. EIIAB), quorum-sensing signaling system (e.g. LuxS), enzymes (including Dex, YidC, CopZ, EzrA, lmrB, SprV, RecA, PdxR, MurI) and small-molecule metabolites.ResultsThis review summarizes the recent progress in the molecular regulatory mechanisms of exopolysaccharides synthesis and biofilm formation inS. mutans.