Thesis (Doctoral)--Bayer. Ludwig-Maximilians-Universität München, 1935.

Thesis (Ph. D.)--University of Southern California, 1999. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Southern California, 1999. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Doctoral)--Bayer. Ludwig-Maximilians-Universität München, 1935.

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.

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.

OBJECTIVE: The aim of this in-vitro study is to assess the effect of cyclic loading fatigue on failure load of CAD/CAM cement-retained implant crowns and screw-retained implant crowns with screw access holes sealed with composite or Enamic inlay. MATERIALS AND METHODS: For the screw-retained implant crowns, Ivoclar e.max and Vita Enamic CAD/CAM (n=44 for each material) and Enamic inlays (n=44) were designed using Sirona in-Lab software system (SW4 4.2.5) and milled using CEREC in-Lab MC XL. All the prepared e.max and Enamic crowns were cemented to Sirona TiBase (B O 4.1 L) using Ivoclar hybrid multilink cement. The access holes were sealed either by using composite or and Enamic inlay (n=22 for each group). For cement-retained implant crowns, Ivoclar e.max, Vita Enamic, and Vita Mark II CAD/CAM (n=20 for each material) and Enamic and Zirconia abutments (n=40 for each group) were designed using Sirona in-Lab software system (SW4 4.2.5) and milled using CEREC in-Lab MC XL. All the prepared zirconia and Enamic abutments were cemented to Sirona TiBase (B O 4.1 L) using Ivoclar hybrid multilink cement. Then, all prepared Ivoclar e.max, Vita Enamic, and Vita Mark II crowns were cemented to the abutments using Multilink Automix cement. After cementation, 10-12 specimens from each group (both screw and cement-retained) were subjected to a static load to failure test in a universal mechanical testing machine (Instron 5566A). The mean failure load for each group was calculated. The other 10 specimens for each group were subjected to cyclic loading fatigue under 40% of static failure load for 50,000 and 100,000 cycles. After cyclic loading, the surviving specimens were tested for static failure load. The comparison of failure load between tested groups was analyzed by one-way ANOVA using JMP Pro 13 with α=0.05. RESULTS: For IPS e-max CAD screw-retained implant crowns, there was a significant difference in the failure load at static and after cyclic fatigue for 50,000 cycles, but no significant difference between static and after cyclic fatigue for 100,000 cycles. For Vita Enamic crowns, there was no significant difference in the failure load at static and after cyclic fatigue for 50,000 cycles and 100,000 cycles. There was a significant difference in the failure load between screw-retained implant crowns sealed with composite and those sealed with Enamic inlay. For IPS e-max CAD /Zr abutment and Vita Mark II/ Enamic abutment cement-retained implant crowns, there was a significant difference in the failure load at static and after cyclic fatigue for 100,000 cycles. For Vita Enamic /Zr abutment cement-retained implant crowns, there was no significant difference in the failure load at static and after cyclic fatigue for 100,000 cycles. CONCLUSION: The screw-retained implant crowns sealed with composite had higher failure load than those sealed with Enamic inlay. The cyclic fatigue has an effect on IPS e.max CAD screw-retained implant crowns, IPS e-max CAD /Zr abutment and Vita Mark II/ Enamic abutment cement-retained implant crowns. The cyclic fatigue has no effect on Vita Enamic screw-retained implant crowns and Vita Enamic/ Zr abutment cement-retained implant crowns.

published_or_final_version / Endodontics / Master / Master of Dental Surgery

Purpose: to assess the retentive strengths of passive fit esthetic anterior restorations using three commercially available cements. Methods: Three resin dies were fabricated from the intaglio surface of each restoration type. Each die was prepared following the current accepted guidelines on primary anterior tooth crown preparation. The three prepared teeth were replicated to produce 30 dies for each of the three restoration types. The prepared teeth were further separated into nine groups of 10 teeth each. Thirty EZ Pedo Crowns, 30 NuSmile Primary Crowns and 30 Unitek crowns were cemented using hand pressure employing the luting cement assigned to the corresponding group. The units were allowed to cure for 7 days. The force required to dislodge the restoration was tested using the Instron Universal Testing Machine. The data was statistically analyzed using a two-way ANOVA to analyze the force required to dislodge the restorations. A two-way logistic regression was used to analyze the failure types. Results: There were no significant differences in restoration retention rates between restoration types (P = 0.4412) but there were significant differences between types of cements used. (P < .0001). The differences with regard to cement types were consistent across the restoration groups (P = 0.7682). Tukey’s HSD multiple comparison procedure indicated FujiCem was significantly more retentive than either Fuji I or Ketac Cem cements and there were no significant differences in restoration retention rates between the Fuji I and Ketac Cem cements. Conclusion: The type of restoration did not matter between cements but cement type did matter with FujiCem cement being more retentive than the other types of cements tested.

Este estudo objetivou avaliar a resistência máxima às forças de compressão entre dois grupos diferentes de coroas em porcelanas livres de metal cimentadas sobre dentes naturais e um grupo formado por dentes caninos naturais hígidos e comparar os resultados obtidos com os de (Chaves, 2001), em seu trabalho de Doutorado onde também se avaliou a resistência máxima às forças de compressão entre coroa metalo cerâmica fraturada e reparada com resina composta com coroa metalo cerâmica integra e dente natural permanente. No presente estudo foram feitos vinte preparos para coroa total em dentes naturais caninos e divididos em dois grupos para confecção de dez coroas do sistema cerâmico aluminizado infiltrado por vidro (Angelus Brasil) e dez coroas em porcelana feldspática Noritake ® (Noritake Kisai CO. Cada grupo de coroas foi cimentado com cimento resinoso auto adesivo RelyX Unicem ® , (3M ESPE, Brasil) com o objetivo de aumentar a resistência da porcelana frente às forças de compressão. O teste de compressão foi realizado em uma máquina de ensaio universal KRATOS, através de uma carga aplicada axialmente no ápice da borda incisal de cada espécime até a fratura. Os dados foram submetidos à análise de Variância ANOVA (p < 0,05) e teste de Tukey para comparação entre grupos. Os resultados mostraram que não houve diferença estatisticamente significante entre a coroa de porcelana aluminizada infiltrada por vidro e o dente natural. A coroa de porcelana feldspática apresentou-se menos resistente com relação ao dente natural e coroa de porcelana aluminizada infiltrada por vidro. / The objective of this study is evaluate the maximum load resistance between two different groups of porcelain metal free crown seated on natural teeth and a group of natural canine and to compare the results gotten with the ones of (Chaves, 2001), in its work of Doutorado where also the ultimate strength to the forces of compression between metalo ceramic broken and repaired with composite resin with ceramic crown metaloceramic integrates and permanent natural tooth. In the present study twenty natural canine teeth were prepared for crown canines and divided in two groups: aluminized porcelain crown infiltrated for glass (Angelus Brazil) and feldspathic Noritake Kisai Noritake (co). Crowns were seated using self adhesive resin cement RelyX Unicem (3M ESPE, Brazil) Compression testing was performed by a universal testing machine (KRATOS) by a load applied axially in incisal of each specimen until occurs the fracture. The data were analyzed by one way analyses of variance (ANOVA) and Tukey test for comparison between groups. The results showed that it did not have statistical significant difference between aluminized porcelain crown infiltrated by glass and natural tooth. The feldspathic porcelain crown presented less resistant than natural tooth and aluminized porcelain crown infiltrated by glass. .