Orientadores: Marcio de Moraes, Luciana Asprino / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-13T02:18:28Z (GMT). No. of bitstreams: 1 Lyrio_MarianaCamiloNegreiros_M.pdf: 2393437 bytes, checksum: f0dfbf68baaeb080347c83445d15e1e9 (MD5) Previous issue date: 2009 / Resumo: O propósito neste estudo foi realizar avaliação mecânica e fotoelástica de dois diferentes sistemas de fixação interna rígida (FIR): placas convencionais e placas com sistema de travamento. Para avaliação mecânica foi realizado teste de carregamento linear em réplicas de hemimandíbulas humanas dentadas seccionadas na região de ramo mandibular, representando uma osteotomia sagital, e fixadas com avanço mandibular de 5 mm. No grupo I a fixação foi realizada com placas convencionais e parafusos monocorticais do sistema 2,0mm e no grupo II utilizou-se placas e parafusos monocorticais com sistema de travamento do sistema 2,0 mm. Para análise estatística foram aplicados Anova e teste de Tukey em nível de significância de 5%, os quais demonstraram não haver diferenças entre os grupos I e II nos testes mecânicos. Para os testes fotoelásticos foram confeccionadas hemimandíbulas humanas dentadas em resina fotoelástica, também seccionadas simulando a osteotomia sagital e fixadas com avanço mandibular de 5 mm, com os mesmos grupos utilizados para os testes mecânicos. Em relação à distribuição de tensões, pode-se observar que as mesmas se concentram ao redor dos parafusos, principalmente naqueles próximos à área de osteotomia para ambos os grupos. Dessa forma, pode-se afirmar que os sistemas de fixação utilizando placa e parafusos convencionais ou com sistema de travamento não apresentaram diferenças estatísticas quanto à resistência, e que a maior concentração de forças está nas áreas próximas às osteotomias, consideradas regiões de maior fragilidade após a OSRM. / Abstract: The aim of this study was evaluate the mechanical and photoelastic behavior of two methods of rigid internal fixation (RIF): conventional plates and locking plates. For mechanical tests polyurethane synthetic hemimandible with seccional sagittal ramus split was used, simulating an advancement of 5 mm. The fixation performed on the Group I was a 2.0 mm conventional plates with monocortical screws and fixation used on group II was a 2.0 locking plates with monocortical locking screws. Anova and Tukey tests were applied (P<5) and no statistical differences were noted between the groups. Hemimandibles were made in photoelastic resin with same groups used in mechanical tests and submitted to photoelastical analysis. In relation to tension distribution in photoelastic analysis, the fringes were concentrated around screws, mainly in areas near the osteotomy for both groups. Based in this fact, the conventional and locking fixations systems did not present statistical differences on resistence, and the major forces was concentrated in regions near the osteotomies lines, that considered fragility before sagittal split osteotomy. / Mestrado / Cirurgia e Traumatologia Buco-Maxilo-Faciais / Mestre em Clínica Odontológica

Thesis (Ph.D.)--University of Western Australia, 2007.

Thesis (M.D.S.)--University of Hong Kong, 2003. / Also available in print.

D.Ing. / This thesis studies the application of newer generation engineering materials, specifically carbon fibre reinforced polymers, as bone plates in cases of fractured bones. The application of bone plates subsequent to bone fracture is a very old orthopaedic technique that has always rendered some problems. The rigidity of the bone plate, and thus the plated system as a whole, is of advantage during the healing phase, but of disadvantage later. Bone remodels itself to most efficiently perform the load bearing required of it. In a plated system, the load is born primarily by the plate and therefore protects the underlying bone, leading to osteoporosis and eventual atrophy. All bone plates are made of a material that is totally foreign to the body, and in most cases these are removed after some healing of the bone had occurred. The majority of current research programmes with respect to bone plates are directed towards biodegradable bone plates that reduces in mechanical strength at approximately the same rate as bone gains in its ability to sustain loads. The principle of stimulating bone growth in cases of delayed union and non-union has been studied since the early 1960's. The studies revealed that bone healing can in fact be enhanced by the introduction of a very small electric current to the fracture site. Variations to the mechanisms and position of application of the current, alternating or direct, are well documented. Although the physiological healing process associated with electrical stimulus remains largely unknown, the principle is well established. The phenomenon of galvanic corrosion has been known since the tum of the century. Where two dissimilar materials are in the presence of a conducting media, the more "reactive" of the two materials will react as an anode or electron donor to the other material. An electric current thus will flow from the one material to the other. Having three existing and known phenomena, namely bone plating, bone healing stimulation and galvanic corrosion raises the question of whether these can be combined to yield a solution superior to any current plating mechanism - a plate that would render sufficient mechanical support but act as an electron source and thus as a bone healing stimulus. The purpose of this study is to assess the biological criteria determining the choice of bone plates (inclusive of mechanical, physiological and electrical criteria) and thereafter selecting a material suitable for this dynamic requirement.

Thesis (MMed)--Stellenbosch University, 2014. / No abstract available

published_or_final_version / Dentistry / Master / Master of Dental Surgery

No description available.

No description available.

The high performance of bone implants depends on the positive response of osteoblasts to the surface of the materials manufactured for the implant. Cell response in turn strongly depends on the nature of the initial interaction of macromolecules involved in cell adhesion and proliferation with the atomic structure of the surface of the material used for the implant. The initial interaction between bone specific extracellular matrix proteins and the solid substrate influences cell response at the cell-implant interface. This interaction is crucial for implant stability, long-term durability, and osseointegration. Despite extensive research undertaken to develop high-quality material for implants in order to improve the cell-substrate interaction, little is known about the significance of the atomic structure of the substrate and the role of molecular machinery involved in cell-substrate interaction. Using a combined approach involving material sciences and cell and molecular biology, the objectives of this research are to evaluate the response of pre-osteoblast and fibroblast cell lines to novel bulk polycrystalline and single crystal titanium based material and assess the role of crystal size and orientation. / Novel bulk nano-structured titanium substrates were produced by the process of high-pressure torsion (HPT). These materials have a significant advantage compared to conventional titanium-based materials by having higher surface wettablity, mechanical properties as well as a distinct surface oxide layer and atomic structure. A co-culture system was adapted to investigate the differential response of pre-osteoblast and fibroblast cell lines to titanium and titanium dioxide single-crystal substrates. / The results of this study provide clear evidence that crystal size and specific crystallographic orientation can be used to improve cell adhesion and proliferation. The nanostructured titanium substrates show strong interaction with pre-osteoblast cells as evident by the higher expression of fibronectin and the formation of extensive focal adhesion. Differential cell behaviour of pre-osteoblasts and fibroblasts are observed in cultures grown on the substrates with specific crystallographic orientations. The degree of cell attachment of the pre-osteoblasts is considerably higher on Ti-(1120) crystal face compared with the fibroblasts. These findings have profound implications for the improved osseointegration and inhibition of fibrosis leading to long-term implant consolidation and stability.

Thesis--University of Oklahoma. / Bibliography: leaves 73-77.