Fluoride toothpaste type dental fluorosis animal model and experimental detection

Objective To test the safety of the use of fluoride toothpaste and the establishment of fluoride toothpaste type dental fluorosis animal model on the basis of public health on the point of view of fluoride toothpaste discussed by fluorosis risk. Methods Choose 3 weeks clean type 42 only SD rats, according to male and female half weight equilibrium principle randomly divided into seven groups with six rats each. Grouping was as follows: group A: negative control; group B: positive control; group C: 50% fluoride toothpaste concentration irrigation stomach group; group D: 100% fluoride toothpaste concentration irrigation stomach group; group E: 30 mg/L NaF solution group; group F: 30 mg/L NaF solution group + 50% fluoride toothpaste concentration irrigation stomach group; group G: 30 mg/L NaF solution group + 100% fluoride toothpaste concentration irrigation stomach group. The general situation and weight of the experimental rats were recorded every week. The urine and serum were collected at 0 day and 112 days. The specimen fluorine content and record analysis were investigated. The mandibular incisor of dental fluorosis conditions were recorded at 0 day, 28 days, 56 days, 84 days and 112 days respectively and according to the dental fluorosis grading scoring statistics. Harvested the rats at the 112th day under anesthesia. Mandible incisors of each rat were stained with the hematoxylin-eosin (HE) to observe the change of teeth structure. Results (1) The concentration of fluorine in rats urine as well as blood fluorine concentration were increased continually as fluorine intake increased. The blood fluorine concentration in rats reached a stationary platform phase when high concentration fluorine was provided. (2) The rats dental fluorosis teeth had various changes as follows: in 28 days, group B enamel surface had visible brown and white horizontal grain from gingival region to incisal margin but did not identify any enamel substantial defect; in 56 days, group G visible brown and white horizontal grain appeared and the reduced transparency in enamel could be seen as well as group B showed a little cretaceous splash piece in the enamel; in 84 days, some of the rats in group B and group G rats appeared chalk like color changes and enamel transparency turbidity. Some of the rats in group E, F showed brown and white horizontal grain in the enamel. Group A, C showed brown, smooth and translucent enamel surface, Only one rat in group D has one rat enamel translucent change with a little cloudy appearance; in 112 days, the chalk sample color changes were seen in the group B and G rats with enamel transparency turbidity. The brown and white horizontal grain appeared in group E, F rats with the 0.5~ 1 mm wide transparent area between the the grains. In overall, rats in group A, C, D had no significant difference compared with the baseline until 84 days. (3) The histopathological observation in rats teeth slice: comparing with group A, the growth lines in group B, group F and group G were obviously deepened, aggravating and more uneven structure arrangement. Group E also showed deepened and aggravating growth lines, but not obvious structure arrangement comparing with group A; However, the growth lines and structure arrangement in group C and D group had no significant changes. Conclusions Preschool children′s use of fluoride toothpaste could promote the generation of dental fluorosis in the high fluoride area. On the other hand, preschool childrens in Optimal fluorine area should strictly follow the guideline of usage of fluoride toothpaste to prevent generation of dental fluorosis together with daily life of the other intake of fluorine. Key words: Fluorosis, dental; Models, animal; Fluorides, toothpaste