EFFECTS OF CO-EXPOSURE TO ENVIRONMENTAL CONTAMINANTS ON THE MORPHOLOGY AND ULTRASTRUCTURE OF MATURATION STAGE AMELOBLASTS YOUNG RATS INCISORS

Abstract

Molar incisor hypomineralization (MIH), also known as "chalky teeth" or "calcareous teeth", is a developmental defect of the enamel that happens during the maturation stage. Teeth with MIH are already found in one out of five children, generating social and financial burdens worldwide. MIH is recognized worldwide as a public health problem. Latin America is the most affected continent. The literature shows that the enamel developmental defects known as MIH and already characterized are hypomineralized and show abundant organic content. There are a few studies that show differences between MIH and normal enamel, and indicate fetal proteins and larger proportions of enamel developmental proteins in MIH defects. However, the causes for MIH in humans are unknown. In animals, exposure to environmental contaminant has been shown to cause enamel defects with similar features of MHI. Therefore, this study aims to test the hypothesis that co-exposure to some environmental contaminants (Bisphenol A/BPA, Lead/ Pb, Fluorine/F) exacerbate hypomineralization defects in dental enamel, and to perform analysis and characterization of the peptides present in the defects by mass spectrometry (LC-MS/MS), as well as analysis of the mineral content by microradiography. Furthermore, in the enamel defects, the electrokinetics flux (EKF) will be tested, in order to promote increase in mineral content and a reduction in organic content. The combinations of environmental contaminants are: BPA (0,5 ug/Kg/day by oral administration) + Lead (30 mg/L in the drinking water), Bisphenol A + Fluoride (50 mg/L in the drinking water), fluoride + Lead, and the controls with BPA, Pb and fluoride alone, and a control with exposure to vehicles. Treatments will be started when dams breed, and will continue throughout pregnancy and lactation, with offspring receiving treatment until day 30 of life. Incisors will be used for organic and mineral analyses, and blood, mandibles, femurs, brains, and livers will be stored for toxic agent determination.For this study, three animals of each group will be perfused and the upper and lower incisors will be used for Transmission Electron Microscopy (TEM) analysis.