Reparação inicial de enxertos ósseos autógenos em bloco ou em particulas: estudo microscópico em mandíbula de cães
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Data
2004
Autores
Paleckis, Laura Guimarães Pagliuso [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A reabsorção óssea associada à perda dos dentes por vezes impossibilita a instalação imediata de implantes dentários. Nesta circunstância, pode ser necessária a reconstrução óssea prévia, realizada por meio de enxertos ósseos autógenos. A compreensão dos fenômenos iniciais da reparação dos enxertos é fundamental para favorecer sua consolidação clínica. Neste estudo, foram realizados enxertos ósseos autógenos em bloco ou em partículas na mandíbula de 6 cães, bilateralmente. Os leitos receptores foram preparados, os blocos foram rigidamente fixados e os enxertos em partículas foram adaptados e condensados. Três animais foram sacrificados após 7 dias e os outros 3, após 14 dias. Os espécimes foram submetidos a análise microscópica. Após 7 dias, os enxertos em bloco exibiram desvitalização, com canais vasculares vazios e interface enxerto-leito constituída por um tecido conjuntivo vascularizado e rico em fibras colágenas. As partículas, desvitalizadas, foram completamente envolvidas por tecido conjuntivo, com áreas de reabsorção osteoclástica. Aos 14 dias, os blocos já eram invadidos por canais de reabsorção, e os canais vasculares de Havers e Volkmann eram alargados e revascularizados junto ao leito. As partículas foram quase completamente reabsorvidas e o tecido conjuntivo circundante já exibia áreas de neoformação óssea. As perfurações do leito e a região adjacente ao parafuso de fixação foram sede de início de osteogênese. Os resultados mostraram que a reparação inicial dos enxertos em bloco caracteriza-se por lenta revascularização a partir do leito receptor, que requer alargamento dos canais vasculares préexistentes, enquanto as partículas são rapidamente reabsorvidas.
Sometimes, bone resorption in association with loss of teeth makes it impossible to immediately perform dental implants. Under this circumstance, previous bone reconstruction would be necessary, through autogenous bone grafts. The understanding of the initial phenomena involved with bone grafting repair is fundamental for a clinical success. In this study, block or particulate autogenous bone grafts were placed bilaterally in mandibles of dogs. The host sites were prepared, the blocks rigidly fixated, and the particulate graft s were adapted and condensed. Three animals were sacrificed after 7 days, and the other 3, after 14 days. The samples were processed for microscopic analysis. After 7 days, the grafted blocks showed devitalization and empty vessel canals. The interface between the host site and the graft presented a vascularized connective tissue rich in collagen fibers. The grafted particles were devitalized and totally embedded in connective tissue. Areas of osteoclastic resorption were noticed in this group. At 14 days, resorption lacunae could be seen in the blocks. Harvers and Volkmann canals were elongated and revascularized at the host site. The particles had already been almost resorbed, and the surrounding connective tissue presented areas of new bone formation. The perforations of the host site and the region adjacent to the fixation screw represented areas where there was a beginning of osteogenesis. The results showed that the initial repair of block grafts was characterized by slow revascularization, starting from the host site, which required enlargement of pre-existing vascular canals. On the other hand, particulate bone grafts were rapidly resorbed and replaced by areas of forming bone.
Sometimes, bone resorption in association with loss of teeth makes it impossible to immediately perform dental implants. Under this circumstance, previous bone reconstruction would be necessary, through autogenous bone grafts. The understanding of the initial phenomena involved with bone grafting repair is fundamental for a clinical success. In this study, block or particulate autogenous bone grafts were placed bilaterally in mandibles of dogs. The host sites were prepared, the blocks rigidly fixated, and the particulate graft s were adapted and condensed. Three animals were sacrificed after 7 days, and the other 3, after 14 days. The samples were processed for microscopic analysis. After 7 days, the grafted blocks showed devitalization and empty vessel canals. The interface between the host site and the graft presented a vascularized connective tissue rich in collagen fibers. The grafted particles were devitalized and totally embedded in connective tissue. Areas of osteoclastic resorption were noticed in this group. At 14 days, resorption lacunae could be seen in the blocks. Harvers and Volkmann canals were elongated and revascularized at the host site. The particles had already been almost resorbed, and the surrounding connective tissue presented areas of new bone formation. The perforations of the host site and the region adjacent to the fixation screw represented areas where there was a beginning of osteogenesis. The results showed that the initial repair of block grafts was characterized by slow revascularization, starting from the host site, which required enlargement of pre-existing vascular canals. On the other hand, particulate bone grafts were rapidly resorbed and replaced by areas of forming bone.
Descrição
Palavras-chave
Ossos - Enxerto, Boca - Cirurgia, Cão, Cirurgia bucal, Transplante ósseo, Surgery, oral, Dogs, Bone transplantation
Como citar
PALECKIS, Laura Guimarães Pagliuso. Reparação inicial de enxertos ósseos autógenos em bloco ou em particulas: estudo microscópico em mandíbula de cães. 2004. 119 f. Tese (doutorado) - Universidade Estadual Paulista, Faculdade de Odontologia de Araçatuba, 2004.