Association of Streptococcus mutans harboring bona-fide collagen binding proteins and Candida albicans with early childhood caries recurrence

Early childhood caries (ECC) recurrence occurs in approximately 40% of treated cases within one year. The association of Streptococcus mutans and Candida albicans with the onset of ECC is well known. Also, S. mutans strains harboring collagen-binding proteins (Cbps) avidly bind to collagen-rich dentin and are linked to increased caries incidence. Here, we investigated the presence of Cbp⁺ S. mutans and C. albicans in saliva and dental plaque of children with varying caries statuses, as well as the salivary microbiome of these children.

In this cross-sectional study, 143 children who were caries-free, treated for ECC with no signs of recurrence after 6 months, or treated for ECC and experiencing recurrence within 6 months following treatment were enrolled. Co-infection with C. albicans and S. mutans, especially Cbp⁺ S. mutans, was strongly associated with caries recurrence. Subjects of the recurrence group infected with Cbp⁺ S. mutans showed a greater burden of C. albicans and of Mutans streptococci in dentin than those infected with Cbp⁻ S. mutans.

Microbiome analysis revealed that Streptococcus parasanguinis was overrepresented in the caries recurrence group. Our findings indicate that Cbp⁺ S. mutans and C. albicans are intimately associated with caries recurrence, contributing to the establishment of recalcitrant biofilms.