Purpose It is known that distortions can occur during impression making and the pouring of casts, and that this distortion may produce inaccuracies of subsequent castings, especially long span castings for implant superstructures. The purpose of this study was to compare the ability of different impression materials to reproduce the positions of 5 implant analogues on a master model, in terms of their accuracy and the accuracy of a resultant cast, relative to the master model. Method The master model was a stainless steel model with 5 implant analogues. The impression materials used were impression plaster (Plastogum), a polyether (Impregum Penta), and two polyvinyl siloxane materials (Aquasil Monophase and Aquasil putty with light body wash). Five impressions were made with each impression material and cast in Satin stone under controlled conditions. The positions of the implants on the master model, the impression copings, and the implant analogues in the subsequent cast were measured using a co-ordinate measuring machine which measures within 4μm of accuracy. Results Statistical analysis using a one factor t-test indicated that distortion occurred in all the impression materials, but inconsistently. Aquasil Monophase reproduced the master model most accurately. Although there was no significant distortion between the Aquasil monophase impressions and the master model or between the impressions and their casts, there were distortions between the master model and the master cast, which highlighted the cumulative effects of the distortions. Impregum’s performance proved to be the most reliable in terms of predictability. Plastogum displayed cumulative distortion and with Aquasil putty with light body, these impression materials had the least reliability. Conclusions Some of the distortions observed are of clinical significance and likely to contribute to a lack of passive fit of any superstructure. The unpredictability of such distortions may mean that the future of accurate impressions and superstructures may lie in the digital world.

Thesis (doctoral)--University of Göteborg, 1991. / Extra t.p. with thesis statement inserted. Includes bibliographical references.

Thesis (doctoral)--University of Göteborg, 1991. / Extra t.p. with thesis statement inserted. Includes bibliographical references.

Thesis (doctoral)--University of Göteborg, 1991. / Extra t.p. with thesis statement inserted. Includes bibliographical references.

Thesis (doctoral)--Universität Köln, 1987. / Vita. Includes bibliographical references (p. 85-97).

Thesis (doctoral)--University of Göteborg, 1991. / Extra t.p. with thesis statement inserted. Includes bibliographical references.

Orientadores: Rafael Leonardo Xediek Consani, Mateus Bertolini Fernandes dos Santos / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-24T21:15:14Z (GMT). No. of bitstreams: 1 Nogueira_MoisesdaCostaFerraz_M.pdf: 1749031 bytes, checksum: 8fa4481a045e127aabb629294129a5b0 (MD5) Previous issue date: 2014 / Resumo: O objetivo neste estudo foi avaliar por meio da análise por elemento finito 3-D, as tensões ocorridas em overdentures com sistemas de retenção barra-clipe, quando diferentes formas da seção transversal (circular, ovóide ou Hader) apresentam diferentes níveis de desajuste vertical (50, 100 e 200 µm) e são confeccionadas com diferentes ligas metálicas (Au tipo IV, Ag-Pd, Co-Cr e Ti cp). Modelos tridimensionais foram feitos utilizando software para modelagem 3-D (SolidWorks 2010) e importados para o software de simulação mecânica (ANSYS Workbench 11). Aperto simulado do parafuso foi realizado até obter assentamento adequado entre infraestrutura e plataforma protética. As análises foram realizadas com o objetivo de obter as tensões Máxima Principal e de von Mises (MPa). Os valores da tensão aumentaram com o aumento do desajuste vertical, assim como a barra Hader proporcionou os maiores valores. Barras circulares feitas com Au tipo IV causaram os menores valores na barra e no parafuso protético. Ligas resilientes mostraram melhores resultados que as rígidas, enquanto a maior complexidade da seção transversal da barra e o maior nível de desajuste vertical aumentaram a concentração das tensões na barra, parafuso protético e tecido ósseo cortical. Conclui-se que as tensões induzidas na barra, parafuso protético e tecido ósseo peri-implantar foram influenciadas pelo aumento do desajuste vertical, complexidade da seção transversal e liga da barra / Abstract: The objective of this study was to evaluate by 3-D finite element analysis tensions occurred in overdentures with bar-clip retention systems, when different cross-sectional geometries (circular, oval or Hader) have different levels of vertical misfit (50, 100 and 200 µm) and were maded from different metallic alloys (type IV Au , Ag-Pd , Co-Cr and Ti cp). Three-dimensional models were maded using 3-D modeling software (SolidWorks 2010) and imported into the software of mechanical simulation (ANSYS Workbench 11). A displacement simulating screw tightening was done until proper fitting of the prosthetic platform infrastructure. The analyzes were performed in order to obtain the Maximum Principal Stress and von Mises (MPa). The stress values increased proportionally with the level of vertical misfit and Hader bar showed the highest values. Circular bars made with Au type IV showed the lowest values on the bar and prosthetic screw. Resilient alloys performed better than hard, while the greater complexity of the cross section of the bar and the highest levels of vertical misfit increased stress concentration on the infrastructure of the bar, prosthetic screw and cortical bone tissue. The stress induced on the bar, prosthetic screw and peri-implant bone tissue were influenced by increased vertical misfit, complexity of cross section and different alloys of the bar / Mestrado / Protese Dental / Mestre em Clínica Odontológica

by Pang Sai Yau. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves [87-90]). / Chapter chapter one： --- introduction / Chapter 1.1 --- General Introduction --- p.1 / Chapter 1.2 --- biology of cancellous bone grafts --- p.2 / Chapter 1.2.1 --- Biology of bone graft incorporation --- p.2 / Chapter 1.2.1.1 --- Osteogenesis --- p.2 / Chapter 1.2.1.2 --- Vascularization --- p.3 / Chapter 1.2.1.3 --- Osteoinduction --- p.3 / Chapter 1.2.1.4 --- Osteoconduction --- p.4 / Chapter 1.2.2 --- Histological changes of bone grafts after bone transplantation --- p.4 / Chapter 1.2.2.1 --- Histologic pictures of cancellous autograft --- p.4 / Chapter 1.2.2.2 --- Histologic pictures of cancellous bone allograft --- p.5 / Chapter 1.2.2.3 --- Summary of the histologic changes of bone grafts --- p.5 / Chapter 1.3 --- application of cancellous bone grafts --- p.6 / Chapter 1.3.1 --- Principles of graft incorporation --- p.6 / Chapter 1.3.1.1 --- Operative site --- p.6 / Chapter 1.3.1.2 --- Graft material --- p.7 / Chapter 1.3.1.2.1 --- Autogenic cancellous bone --- p.8 / Chapter 1.3.1.2.2 --- Autogenic cortical bone --- p.9 / Chapter 1.3.2.2.3 --- Vascularized autogenic bone grafts --- p.9 / Chapter 1.3.2.2.4 --- Bone allografts --- p.10 / Chapter 1.3.2.2.5 --- Graft adjuncts and substitutes --- p.11 / Chapter 1.3.2.3 --- Systemic factors influencing gaft incorporation --- p.13 / Chapter 1.3.2.4 --- Local factors influencing graft incorporation --- p.13 / Chapter 1.3.3 --- Bone graft complications --- p.13 / Chapter 1.3.4 --- Placement of a graft --- p.14 / Chapter 1.3.5 --- Bone graft harvesting --- p.15 / Chapter 1.3.5.1 --- Iliac bone graft --- p.15 / Chapter 1.3.5.2 --- Femoral head bone allograft --- p.16 / Chapter 1.4 --- Application of flow conductance concept in a cancellous bone graft --- p.17 / Chapter 1.4.1 --- Physical structure of cancellous bone --- p.17 / Chapter 1.4.2 --- Porosity of cancellous bone --- p.17 / Chapter 1.4.3 --- Flow conductance concept --- p.18 / Chapter chapter two： --- material and method / Chapter 2.1 --- Transplantation of cancellous bone graft - Rabbit model --- p.19 / Chapter 2.1.1 --- Preparation of porcine cancellous bone graft --- p.19 / Chapter 2.1.1.1 --- Bone drilling --- p.19 / Chapter 2.1.1.2 --- Defat and freeze-dry --- p.20 / Chapter 2.1.2 --- Flow conductance measurement --- p.21 / Chapter 2.1.2.1 --- Porosity measurement --- p.21 / Chapter 2.1.2.2 --- Conductance measurement --- p.24 / Chapter 2.1.3 --- Rabbit model --- p.26 / Chapter 2.1.4 --- Methods of assessment --- p.29 / Chapter 2.1.4.1 --- Intraosseous pressure measurement --- p.29 / Chapter 2.1.4.2 --- Histologic study --- p.30 / Chapter 2.1.4.3 --- Blood flow study - use of tracer microspheres --- p.30 / Chapter 2.2 --- Flow conductance measurement of human cancellous bone --- p.34 / Chapter chapter three： --- results / Chapter 3.1 --- Results of the effects of various conductance of the grafts on bone healing in animal model --- p.38 / Chapter 3.1.1 --- Intraosseous pressure measurement --- p.38 / Chapter 3.1.2 --- Histological study --- p.40 / Chapter 3.1.3 --- Blood flow study of cancellous bone grafts --- p.52 / Chapter 3.2 --- Human specimens study --- p.62 / Chapter chapter four： --- discussion / Chapter 4.1 --- Discussion of the results in vivo study --- p.66 / Chapter 4.1.1 --- Intraosseous pressure measurement - a baseline study --- p.66 / Chapter 4.1.2 --- Effects of flow conductance of porcine cancellous grafts on bone regeneration --- p.67 / Chapter 4.1.2.1. --- Threshold conductance --- p.67 / Chapter 4.1.2.2. --- Histological score --- p.68 / Chapter 4.1.3 --- Discussion of graft healing from the blood flow study --- p.70 / Chapter 4.1.3.1 --- Tibia blood supply in relation to bone healing --- p.70 / Chapter 4.1.3.2 --- Effect of different flow conductance on blood flow changes in the tibia-graft structure --- p.72 / Chapter 4.1.4 --- "Comparison of length, porosity and conductance as the parameter on graft healing" --- p.74 / Chapter 4.2 --- Discussion on human bone specimens study --- p.76 / Chapter 4.3 --- General discussion --- p.78 / Chapter 4.3.1 --- The limitation of the animal model --- p.78 / Chapter 4.3.2 --- Some problems related to the clinical aspects --- p.79 / Chapter chapter five： --- conclusion --- p.81

Thesis (Ph. D.)--Drexel University, 2004. / Includes abstract and vita. Includes bibliographical references (leaves 168-182).

Diss. (sammanfattning) Göteborg : Göteborgs universitet, 2006. / Härtill 5 uppsatser.