Efeito do fluor sobre a matriz organica do esmalte dentario de camundongos / Fluoride effect in the secretory-stage enamel organic extracellular matrix of mice

AUTOR(ES)
DATA DE PUBLICAÇÃO

2010

RESUMO

Dental fluorosis is characterized by alterations in the aspect of mature enamel due to hypomineralization, it is caused by chronic ingestion of fluoride during tooth development. Fluoride seems to influence on formation of enamel organic matrix. Previous studies have shown that the organic extracellular matrix of the enamel secretory phase is birefringent, evidencing the presence of an ordered supramolecular structure, and that the birefringence can be altered by genetical and environmental factors that also affect mature enamel. The aim of this work was to analyse the effect of fluoride on the matrix maturation and supramolecular organization in A/J, CBA and DBA/2 mice strains and its association to fluoride systemic levels in plasma, bones and urine. There are different patterns of susceptibility to fluorosis among these strains. The effect of fluoride on enamel organic matrix was studied by birefringence and absorbance analysis of Ponceau SS stained sections. Ninety six mice (32 A/J strain, 33 CBA strain and 31 DBA/2 strain) were randomly distributed in three groups (0, 11.25 and 45 ppm of fluoride in drinking water) submitted to a 49-days treatment. Fluoride levels in bones, plasma and urine were determined by F specific electrode. Polarizing microscopy was used to analyse the birefringence of enamel organic matrix and light microscopy was used to determinate the matrix absorbance. As result, 11.25 ppmF group of A/J strain showed least effect of fluoride on birefringence. Colouring alterations were observed in the mature enamel on 11.25 and 45 ppmF groups of A/J strain. However, 11.25 and 45 ppmF groups of DBA/2 strain presented highest levels of fluoride in bones and plasma. Fluoride did not change the protein amount of enamel matrix during secretion stage. Conclusion: A/J strain was the most susceptible to dental fluorosis because it showed more alterations in the mature enamel. However, enamel organic matrix of A/J strain was the least affected during the secretion phase. Fluoride promoted a change in the supramolecular organization of enamel organic matrix during the secretion stage. This compound caused a birefringence decrease without causing a significant reduction on matrix protein amount. A/J strain, even being the most susceptible to dental fluorosis, showed the lowest levels of fluoride in plasma and bones

ASSUNTO(S)

fluoretos birefringence amelogenesis microscopy birrefringencia fluorides polarization amelogenese microscopia de polarização

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