Dental enamel following maternal exposure to different fluoride concentrations: Physicochemical and functional approaches in rats offspring

Excessive fluoride (F) exposure is associated with adverse effects at different life stages and can affect various biological systems, including the mineralized tissues of the oral cavity. However, there is limited evidence that early F exposure during pregnancy and lactation impairs the development of offspring dental enamel. From a translational perspective, this study aimed to investigate the effects of F at different concentrations on the ultrastructural, physicochemical, and functional properties of dental enamel in the offspring of rats exposed during the prenatal and lactation periods. Pregnant Wistar rats were divided into: control (deionized water), 10 mg F/L, and 50 mg F/L. F exposure was conducted from the first day of pregnancy until the 21st day of lactation. Enamel samples from the offspring's upper incisors were collected to evaluate F levels, ultrastructural characteristics, and physicochemical composition through scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Raman spectroscopy, and X-ray diffraction (XRD). The results showed that increased levels of F triggered changes in phosphate and carbonate contents, with no alterations in the ultrastructure of the prisms or enamel crystallinity. Nevertheless, a significant increase in enamel hardness was observed in F exposed groups. These findings suggest that while F exposure did not affect the ultrastructure integrity of enamel, it significantly altered its chemical composition and mechanical properties. Our data suggest that maternal exposure to excessive levels of F during the prenatal and lactation periods leads to increased enamel hardness, which could impact enamel friability.