Birrefringencia da matriz organica do esmalte dentario




The formation of dental enamel is a complex biological process, which depends on a well-structured organic matrix. Recent evidences indicate that the components of this matrix can interact to form a supramolecular structure. The biological significance of this supramolecular organization is not clearly understood. In part this occurs due to methodological difficulties to perform direct morphological observations of the structured enamel organic matrix. The detection of anisotropic properties by polarizing microscopy has been extensively used to detect and measure the macromolecular organization in ordinary histological sections. The aim of this work was to study the birefringence of enamel organic matrix during the development of rat molar and incisor teeth. Wistar rats with approximately 300g were anesthetized with chloral hydrate and perfused with 2% paraformaldehyde 0.5% glutaraldehyde in 0.2 M phosphate buffer solution, pH 7.2. Upper incisor teeth and hemimandibles were then immersed in the fixative solution for 16h. Decalcification was performed by immersion of upper incisor teeth and hemimandibles in a mixture of 5% nitric acid and 10% formaldehyde for 6h and 24h, respectively. After dehydration, samples were embedded in paraffin and 5mm thick longitudinal sections were obtained. The sections were treated with xylol for removal of the paraffin, and hydrated. Form birefringence curves were obtained after measurements of optical retardations in imbibing media with different refractive indices. Our observation showed that enamel organic matrix of rat incisor and molar teeth is strongly birefringent. The birefringence starts at early secretion and disappears at maturation phase. The results show that enamel organic matrix presents a highly ordered supramolecular structure. The analysis of enamel organic matrix birefringence may be used to detect the effects of genetic and environmental factors on the supramolecular orientation of enamel matrix and its association with enamel defects.


microscopia de polarização birrefringencia birrefringence microscopy polarization esmalte dentario dental enamel

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