Effects of Non-albicans Candida species and Streptococcus mutans on cariogenicity

Early childhood caries is a major problem in dental public health. Microorganisms,especially Streptococcus mutans (S. mutans), is an important causative factor. Recent studiesreported that the presence of Candida albicans together with S. mutans in plaques of childrenwith dental caries enhances cariogenicity. However, no information exists regarding the effectof non-albicans Candida species (NACs), which are also found in children with caries.Therefore, this study aimed to examine the effects of two important non-albicans Candidaspecies, Candida dubliniensis (C. dubliniensis) and Candida parapsilosis (C. parapsilosis), whenco-cultured with S. mutans on acid production and biofilm formation, which are importantcariogenic factors. The results showed that the pH of dual-species culture was lower than thatof Candida alone and was lower than the critical pH that can demineralize enamel when S.mutans was co-cultured with C. dubliniensis or C. parapsilosis in media supplemented withsucrose for 36 hours. Moreover, biofilm formation of dual-species culture was significantlyhigher than the sum of single-species biofilm. In conclusion, co-culture of C. dubliniensis or C.parapsilosis together with S. mutans resulted in increased biofilm formation and a pH that waslower than the critical pH of enamel. This could lead to an increase in cariogenicity of themicroorganisms.