• JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
 
  Bookmark and Share
 
 
Habilitation Thesis
DOI
10.11606/T.42.2010.tde-05042010-100804
Document
Author
Full name
Victor Elias Arana-Chavez
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2001
Committee
Linden, Rafael (President)
Araujo, Vera Cavalcanti de
Moraes, Flavio Fava de
Smith, Ricardo Luiz
Zorn, Telma Maria Tenorio
Title in Portuguese
Formação e mineralização dos tecidos dentários e do tecido ósseo.
Keywords in Portuguese
Cemento dentário
Dentina
Esmalte dentário
Mineralização dentinária
Osso e ossos
Abstract in Portuguese
Apesar dos avanços na biologia dos tecidos mineralizados, aspectos do seu processo de formação e, principalmente, do início da sua mineralização, são assuntos ainda controversos. No presente trabalho, dentina, cemento, esmalte e osso em formação foram examinados ultra-estruturalmente, utilizando criofratura, citoquímica e imunocitoquímica, combinadas com criosubstituição e irradiação com microondas, com o intuito de evitar a perda de componentes da matriz, incluindo os primeiros cristais de mineral, e melhorar a preservação destes tecidos. Os resultados mostraram que, no osso e na dentina, vesículas da matriz derivadas de osteoblastos e odontoblastos em diferenciação iniciam a deposição de mineral. As células desenvolvem junções oclusivas que compartimentalizam parcialmente a matriz jovem, enquanto estas terminam sua diferenciação e polarização, passando a secretar proteínas não colágenas para a progressão da mineralização. No cemento e no esmalte, a mineralização inicia-se sem participação de vesículas da matriz. Entre dentina radicular e cemento ocorre a formação da camada hialina, na região da membrana basal interna da bainha radicular epitelial de Hertwig. Na amelogênese, amelogeninas são secretadas durante a diferenciação dos ameloblastos, antes do estabelecimento da fase secretora propriamente dita. A imunodetecção dessas proteínas foi possível pela aplicação dos métodos acima citados, principalmente a irradiação com microondas. Na fase secretora da amelogênese, imagens ultra-estruturais sugerem que estas proteínas seriam montadas em estruturas esféricas (nanosferas), como tem sido sugerido por outros autores após estudos in vitro. Assim sendo, a mineralização dos tecidos dentários e do osso parece iniciar-se sob comando celular, sendo que a progressão do processo seria devido a mecanismos mediados por componentes da matriz.
Title in English
Development and mineralization of dental tissues and bone.
Keywords in English
Bone
Cementum
Enamel
Mining
Ultrastructure
Abstract in English
Although considerable advances have been made on biology of mineralized tissues, their development and the onset of mineralization remain controversial. In the present study, early developing dentine, cementum, enamel, and bone were ultrastructurally examined by freeze-fracture, cytochemistry and high-resolution immunocytochemistry. These approaches were combined with freeze-substitution and microwave irrradiation for avoiding the loss of several matrix components as well as the first mineral crystals, while yielding a better tissue preservation. In bone and dentine, results showed that mineral deposition begins in association with matrix vesicles, which are released by differentiating osteoblasts and odontoblasts. These cells develop focal tight junctions, which determinate the partial compartmentalization of matrix. Then, cells finish their differentiation and polarization, and start to secrete specific noncollagenous proteins for allowing the progression of mineralization from matrix vesicles to the adjacent matrix. On the other hand, mineralization starts without participation of matrix vesicles in cementum and enamel. Hyaline layer forms between root dentine and cementum at the region of the inner basement membrane from Hertwig's epithelial root sheath. In amelogenesis, some amelogenin molecules are secreted by differentiating ameloblasts, before the establishment of secretory stage. Immunodetection of these enamel proteins at early stages was possible by applying the methods above, especially microwave irradiation, which rapidly immobilizes them. At the secretory stage of amelogenesis, amelogenin appear to form spherical structures (nanospheres), as suggested by previous in vitro studies. It is concluded that, in general, mineralization of dental tissues and bone appears to begin by cell-mediated events. Subsequently, progression of mineralization appears to occur by matrix-mediated mechanisms.
 
WARNING - Viewing this document is conditioned on your acceptance of the following terms of use:
This document is only for private use for research and teaching activities. Reproduction for commercial use is forbidden. This rights cover the whole data about this document as well as its contents. Any uses or copies of this document in whole or in part must include the author's name.
Publishing Date
2010-04-05
 
WARNING: Learn what derived works are clicking here.
All rights of the thesis/dissertation are from the authors
CeTI-SC/STI
Digital Library of Theses and Dissertations of USP. Copyright © 2001-2019. All rights reserved.