Objectives: To compare fracture strength and fatigue resistance of ceramic (ProCAD, Ivoclar-Vivadent)(C) and resin composite (Paradigm MZ100, 3M/ ESPE)(R) crowns made with CEREC-3D. Methods: A prepared ivorine molar tooth was duplicated to produce 40 identical prepared specimens made of epoxy resin (Viade). Twenty (C) crowns and 20 (R) were cemented to their dies using resin cement. Ten of each group were subjected to compressive loading to fracture. The remaining 10 of each group were subjected to mechanical cyclic loading for 500,000 cycles. The survivors were subjected to compressive loading to fracture. Results: No significant difference in mean fracture load was found between the two materials. However, only 30% of the (C) crowns vs. 100% of the (R) crowns survived the cyclic loading test. Conclusions: (R) crowns demonstrated higher fatigue Resistance than (C) crowns in-vitro and might better resist cracking in-vivo.

Master of Science in Dentistry / This work was digitised and made available on open access by the University of Sydney, Faculty of Dentistry and Sydney eScholarship . It may only be used for the purposes of research and study. Where possible, the Faculty will try to notify the author of this work. If you have any inquiries or issues regarding this work being made available please contact the Sydney eScholarship Repository Coordinator - ses@library.usyd.edu.au

This essay comprises a study of the bridal crowns of Tjust, with respect to their national history, concept and aspect of mythological symbol. The tradition of bearing the parochial bridal crown is closely associated with religious medieval politics, and has also come to include elements of superstition and folklore. Attention is paid to these aspects dealing with the position of the bridal crown within current forms of tradition and culture and the impact on brides of this day and age. As the tradition of Church-owned bridal crowns is intrinsic to this country, and especially in the area of which Tjust is a part, possible solutions to the continued tradition are investigated.

Thesis (M. D. S.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 48-67). Also available in print.

Master of Science in Dentistry / This work was digitised and made available on open access by the University of Sydney, Faculty of Dentistry and Sydney eScholarship . It may only be used for the purposes of research and study. Where possible, the Faculty will try to notify the author of this work. If you have any inquiries or issues regarding this work being made available please contact the Sydney eScholarship Repository Coordinator - ses@library.usyd.edu.au

Thesis (Ph. D.)--University of Sydney, 2002. / Includes list of published articles and presentations: leaves xxxii-xxxiii. Includes bibliographical references. Also available in print form.

Thesis (M.S.)--Ohio State University, 2009. / Title from first page of PDF file. Includes vita. Includes bibliographical references (p. 26-30).

Thesis (M.S.)--University of Tennessee Health Science Center, 2009. / Title from title page screen (viewed on October 8, 2009). Research advisor: Edward F. Harris, Ph.D. Document formatted into pages (x1vii, 470 p. : ill.). Vita. Abstract. Includes bibliographical references (p. 151-160).

As excelentes propriedades mecânicas da zircônia fazem com que ela seja o material cerâmico de eleição para as coroas e próteses fixas posteriores. Porém, os problemas relacionados à fratura ainda persistem. A falta de suporte das infraestruturas às cerâmicas de revestimento é indicada como uma possível causa. O presente estudo visou avaliar através de testes laboratoriais se as infraestruturas metálicas e cerâmicas com o desenho convencional ou modificado apresentam diferença estatisticamente significante quanto à redução de complicações mecânicas, como fraturas e trincas na cerâmica de revestimento ao receberem cargas axiais nas cristas marginais de coroas de um primeiro molar inferior, por meio das seguintes hipóteses nulas: 1) a resposta à fadiga nas cristas marginais não aumentará a presença de danos nas coroas; 2) o desenho da I.E. não modificará a presença de danos nas coroas, independente do material utilizado. Quarenta coroas unitárias foram confeccionadas sobre preparos padronizados e divididos em 4 grupos: grupo I (infraestrutura convencional de Cobalto-Cromo); grupo II (infraestrutura modificada de Cobalto-Cromo); grupo III (infraestrutura convencional de Zircônia - IPS Emax ZirCAD); grupo IV (infraestrutura modificada de Zircônia - IPS Emax ZirCAD). Estas coroas foram submetidas ao teste de resistência à fadiga por meio da ciclagem dinâmica em água (106 ciclos ou até a fratura com carga variando de 30-300 N). Aplicou-se a carga inicial com o endentador cerâmico de dissilicato de lítio (IPS Emax Press) na crista marginal mesial, e após o término do ciclo, na distal, alternativamente. A ciclagem foi interrompida em intervalos de 125 mil ciclos a procura de danos com auxílio de estereomicroscopia. Ao final, as coroas fraturadas foram submetidas à microscopia eletrônica de varredura e as não fraturadas foram incluídas em resina epóxi e polidas sequencialmente para a análise dos danos. Cada corpo de prova recebeu escores de acordo com o tipo de falha apresentado. Utilizou-se o teste Kruskal-Wallis para verificar diferença estatística entre os grupos e o teste de Dunn para comparações múltiplas entre os grupos. Os resultados mostraram que há diferença estatisticamente significante entre os grupos, entretanto não houve diferença entre os grupos do mesmo sistema cerâmico. Concluiu-se que a hipótese 1 foi aceita e a 2 rejeitada. / The excellent mechanical properties of zirconia make it to be the material of choice for ceramic crowns and posterior fixed prostheses. However, problems still exist related to the chippings. The lack of framework support to ceramic veneer is indicated as a possible cause. This study aimed to evaluate through laboratory tests if metallic and ceramic framework with conventional or modified design show statistical difference in reducing mechanical complications, such as chipping or fracture of the ceramic veneer on receiving axial loads in marginal ridges of the first molar inferior crowns through the following null hypotheses: 1) the response to fatigue in marginal ridges will not increase the presence of damage to the crowns; 2) framework`s design will not modify the presence of damage to the crowns, regardless of the material used. Forty crowns were manufactured on standardized preparations and divided into four groups: group I (conventional framework Cobalt-Chromium), group II (modified framework Cobalt-chromium), group III (conventional framework Zirconia - ZirCAD IPS Emax) and group IV (modified framework Zirconia - IPS Emax ZirCAD). These crowns were subjected to cyclic loading in a fatigue machine and submerged in water (1.000.000 cycles or until the fracture - load range at 30-300 N). The initial load was applied on the mesial marginal ridge with indenter ceramic Lithium disilicate (IPS Emax Press), and after the end of the cycle, the distal alternatively. The cycling was interrupted at a prescribed number of loading cycles (125.000) and crowns were inspected for damage accumulation under a stereomicroscope. In the end, fractured crowns were submitted to scanning electron microscopy and crowns without fractures were embedded in epoxy resin and sequentially polished for the analysis of the damage. Each sample received scores according to the type of failure presented. Statistical analysis was carried out with Kruskal-Wallis test and multiple conparisons between groups were carried out with Dunn wed significant differences between groups, however there was no difference between the groups of the same ceramic systems. It was concluded that the first hypothesis was accepted and the second hypothesis was rejected.

Atualmente, os implantes são utilizados em diversos tipos de tratamento na reabilitação oral. Para manutenção da osseointegração, é essencial que o conjunto prótese/implante/osso seja submetido a forças às quais estejam aptos a suportar. Os diferentes tipos de desadaptações das infraestruturas das próteses sobre implantes são fatores que podem contribuir para o aumento das tensões na região peri-implantar. Este estudo teve como objetivo avaliar a influência das desadaptações angulares unilaterais na distribuição de tensões na região periimplantar de pilares tipo UCLA, no momento da pré-carga e carga axial. Infraestruturas de CoCr, confeccionadas utilizando-se pilares tipo UCLA, foram divididas em quatro grupos: Grupo A (adaptado), Grupo B, Grupo C e Grupo D (50, 100 e 200 &#x3BC;m de desadaptação unilateral angular por vestibular, respectivamente). Cada grupo foi representado por quatro infraestruturas (n=4). Quatro implantes (4.1mm/15mm) foram posicionados em uma matriz metálica, onde posteriormente foi vazado o poliuretano (PU), com função de simular o tecido ósseo. Quatro extensômetros (strain gauges) foram posicionados na região vestibular, distal, lingual e mesial de cada implante, para aferir a quantidade de deformação; cada grupo foi posicionado em seu respectivo implante. Foram realizados dois testes: o teste de pré-carga com um torque de 32Ncm e o teste de carga com uma força axial estática de 300N. Cada infraestrutura foi sujeita aos dois testes, por cinco vezes. Para análise estatística dos dados, foram utilizados ANOVA (dois critérios) e o teste de Tukey (p<0,05). Os resultados mostraram que os grupos A e B tiveram menos deformação da região peri-implantar em ambos os testes, quando comparados aos grupos C e D. A estatística também mostrou que o Grupo A apresentou melhor distribuição de tensões em sua região, peri-implantar quando comparado aos outros três grupos (p<0,05). Como conclusões, este estudo mostrou que as desadaptações influem na distribuição das tensões da região peri-implantar e que quanto maior o nível de desadaptação, mais altas são as tensões geradas. / Nowadays implants are used in several kinds of oral rehabilitation treatments. For the osseointegration maintenance it is important that crow/implant/bone are subjected to forces which are able to withstand. Different kinds of misfit on the crown frameworks are factors that could lead to an increase of strain around the implanted bone. This study aimed to evaluate the influence of the unilateral angular misfit in frameworks made of UCLA on the peri-implant strain distribution, subjected to preload and axial load. Frameworks made of chrome-cobalt were fabricated on UCLA abutments and divided in 4 groups: Group A (no misfit), Group B, Group C, Group D (50, 100, and 200 of unilateral angular misfit by buccal side, respectively). Each group was represented for 4 frameworks (n=4). Four implants (4.1mm/15mm) were positioned in a metallic matrix which was subsequently poured the polyurethane (PU) to simulate the bone. Four strain gauges were positioned on the buccal, distal, lingual and mesial sides of each implant to assess the amount of strain, each group was connected on its respectively implant. It was performed 2 tests: the preload test with a 32Ncm torque and the load test by applying an axial force of 300N. Each framework was subjected to the both test five times. To the statistics analysis ANOVA (2 ways) and Turkeys test were performed. The results showed that the Groups A and B presented less deformation when compared to Groups C and D. The statistics also showed that the Group A presented better distribution of strain on its peri-implant bone when compared to the other three groups (p<0,05). In conclusion this study showed that misfit had influence on the strain distribution on the peri-implant bone and that strain increased on the Groups C and D which presented higher levels of misfit.