[10] S. oralis is one of a few pioneer species important in early colonisation of the dental pellicle, where it establishes an eubiotic biofilm believed to be protective for teeth.

[5][10][11] It discourages competition by other mouth commensals and pathobionts such as S. mutans and Candida albicans implicated in dysbiotic biofilm formation by sequestering (i.e. accumulating and storing) nutrients and releasing metabolites such as H2O2.

[5][12] A recent study by Leo et al. has investigated the potential mechanism employed by S. oralis to achieve biofilm establishment.

[11] The study described a novel protease therein named MdpS released extracellularly by S. oralis, which directly breaks down MUC5B, an O-glycosylated protein which constitutes the majority of the dental pellicle.

S. oralis has been implicated in opportunistic cases of bacteraemia, septicaemia and meningitis in immunocompromised patients, usually in relation to chronic dental disease and/or prior treatment which could provide a point of entry.