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bioRxiv · 10.64898/2026.08.18.745531

Time-dependent effect of fluoride on caries lesions development in a rat caries model

Banerjee, A.·Sunkara, S.·Capalbo, L.·Yoshino, N.·Tenuta, L. M. A.
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Abstract

Since model dose-response is critical when assessing caries lesion development over time, this study evaluated the influence of fluoride dose and treatment duration on caries progression in a rat caries model. Streptococcus mutans-infected Sprague-Dawley rats were treated with deionized water, 226 ppm F-, or 2,260 ppm F- twice daily for 3, 4, or 5 weeks. Caries lesions were assessed using Larson's modification of the Keyes scoring system and complemented by micro-computed tomography (microCT). Intraoral fluoride availability, serum and bone fluoride concentrations and microbial counts were also determined. Fluoride reduced caries severity in a dose- and time-dependent manner. While early enamel lesions were detected in all groups, extensive dentine lesions increased over time, in a dose-dependent manner, in the control and 226 ppm F- groups, and were not observed in the 2,260 ppm F- group after 5 weeks. Intraoral and bone fluoride availability increased significantly with fluoride concentration and treatment duration, whereas serum fluoride levels reflected fluoride dose instead of treatment duration. MicroCT-derived enamel volume correlated negatively with both total and extensive caries scores, supporting its utility as an objective measure of lesion severity. In conclusion, extending model length from 3 to 5 weeks increased the severity of caries lesions in a dose-dependent manner. Fluoride intraoral availability and bone fluoride also demonstrated a dose and time-dependent response.

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Banerjee, A., Sunkara, S., Capalbo, L., Yoshino, N., Tenuta, L. M. A.. 2026-08-23. Time-dependent effect of fluoride on caries lesions development in a rat caries model. https://doi.org/10.64898/2026.08.18.745531

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