PRENATAL EXPOSURE TO NaF IMPAIRS DENTAL ERUPTION IN RATS

Objectives: Tooth eruption (TE) is a tightly regulated process in which bone resorption plays a crucial role. There is little information about the effects of chronic fluoride (F^-) exposure during fetal and early postnatal period on alveolar bone and tooth eruption.
To evaluate by histomorphometry the bony crypt of developing first mandibular molar and its degree of tooth eruption in offspring exposed to NaF in drinking water during gestation and lactation.
Methods: Offspring of 10- and 15-days-old (n=5 per group), from two groups of mothers (n=6) were used: a) controls (0.3 mg/L NaF); b) treated (50 mg/L NaF). The treatment was performed during pregnancy and lactation. All animals were euthanized by cervical dislocation. F^- concentration of gastric content samples of offspring was determined by the use of ion selective electrode. Their mandibles were removed and histologically processed to obtain buccolingual sections stained with H&E. In sections of first mandibular molar bony crypt of 10-days-old pups, the following histomorphometric parameters were evaluated: trabecular bone volume [BV/TV (%)] and number of osteoclasts/area (N.Oc/mm²). At 15-days-old, degree of tooth eruption [TE (µm)] was determined. Results were expressed as mean ± SE and analyzed by Student´ t test.
Results: F^- gastric content of 15-days-old pups from NaF treated mothers was elevated compared to the control group (p <0.05). BV/TV (%) was higher in bony crypt of pups born to NaF treated mothers compared to their controls (48.11±2.88 vs. 39.09±1.12; p<0.05). In line with this, N.Oc/mm² was lower in treated group (0.047±0.02 vs. 0.242±0.02; p<0.01). In addition TE (µm) was lower in treated group compared to control (-1061.84±17.01 vs. -899.06±21.43; p<0.01).
Conclusions: Lower recruitment of osteoclasts in 10-days-old pups born to NaF treated mothers may affect tooth eruption at 15-days-old. Further studies will allow elucidating the mechanisms triggered by F^- in this process.