The impact of chronic fluoride exposure on dental integrity and growth in male Wistar rats at different developmental stages

Purpose: Fluoride is a naturally occurring water contaminant. Prolonged exposure to this element has been shown to have adverse effects on different tissues, as demonstrated by numerous experimental and epidemiological studies. Additionally, fluoride can cross the placental barrier and is present in breast milk, leading to prenatal exposure in areas with endemic fluorosis. The aim of this study is to examine the impact of chronic fluoride exposure during various developmental stages on dental health and growth in male Wistar rats. Methods: Adult Wistar rats were randomly assigned to fluoride exposure groups (10, 100, and 150 ppm F-) and a control group. The animals began treatment 14 days prior to mating. The litters were weaned at 21 days of age, and the males continued the same exposure concentration until they were 90 days old. Likewise, the same concentrations were used in male Wistar rats that were 21 days old until they reached 90 days of age. Food and water consumption, as well as body weight records, were kept weekly throughout the experiment. At the end of the treatment, dental evaluations were performed, and blood samples were taken to determine serum fluoride concentrations. Results: The litters of the fluoride-treated groups showed a decrease in the number of live births and a lower weight at weaning. The offspring of the highest fluoride group exposed (150 ppm F-) had a significant reduction in both water and food consumption, while body weight gain was lower in all treated groups compared to the control group. All groups exposed to fluoride exhibited an increase in serum fluoride levels, as well as moderate to severe lesions in the incisors in a concentration-dependent manner. However, the group that was exposed to 100 ppm F- after weaning showed a lower total weight gain, a higher score on the dental evaluation scale, and a higher serum concentration of F-compared to the animals that were exposed to the same concentration since gestation. Conclusions: This study presents evidence of the negative impact of high concentrations of F- on adult individuals, including reproductive and developmental effects in those exposed during gestation and continuing chronic consumption into adulthood. Furthermore, the study highlights that the effects of chronic F- exposure vary depending on the developmental stage of the individual at the time of exposure.