Fluoride-Based Validation of a Dynamic Microcosm Biofilm Model for Root Caries-Like Lesions

Objective To assess the effect of distinct fluoride concentrations ([F]) on root dentin carious lesions produced by the MOCS. Materials and Methods Microcosm biofilms were grown for 4 days on bovine root dentin discs from saliva of caries-free donor, under intermittent sucrose flow (5%, 0.25 ml/min, 6 min, 3×/day), and treated with NaF solutions at 0 (control), 450, or 1,350 ppmF, twice daily. Response variables included microbial composition (CFU/mg biofilm), biofilm fluoride concentration (µgF/mg biofilm), and dentin demineralization (% surface hardness change; %SHC). Results Fluoride treatments at 450 ppmF and 1,350 ppmF significantly reduced %SHC compared to 0 ppmF (p ≤ 0.035, Tukey). The %SHC was 64.1 in the control group, and 25.1 and 27.1 in biofilms exposed to 450 ppmF and 1,350 ppmF, respectively (linear regression, R = 0.57, p < 0.013). No significant differences were found in microbial composition in respect to total microorganisms, total aciduric microorganisms and mutans streptococci counts among the groups (p > 0.05). Biofilms exposed to 1,350 ppmF present [F] statistically higher than control group (p < 0.001). Conclusion The MOCS demonstrated an appropriate fluoride remineralization response, supporting its validity as a pre-clinical model for testing anticariogenic agents. Clinical Relevance : This study contributes to scientific advancement in cariology by validating the MOCS as a suitable model for studies aiming at preventing and controlling root caries.