Im Rahmen der Untersuchungen wurden an 60 auf Implantatabutments zementierten Einzelzahnkronengerüsten aus Zirkoniumdioxid Abzugsversuche durchgeführt, um die zur Dezementierung der Kronengerüste nötigen Kräfte zu ermitteln. Als variable Parameter dienten hierbei drei unterschiedliche Abutmentgeometrien, sowie unterschiedliche Zementsysteme. Mittels des beschriebenen CAD/CAM- Verfahrens wurden die Kronengerüste aus Zirkoniumdioxid hergestellt. Die Zugversuche wurden mit der Universalprüfmaschine Zwick Z007 (Zwick, Ulm) durchgeführt und mittels „TestXpert“ (Software Zwick, Ulm) ausgewertet. Die nötige Kraft, welche zu einem vollständigen Abriss der Zirkoniumdioxidgerüste von dem Implantatabutment führt, wurde in Newton gemessen. In den Ergebnissen zeigt sich eine signifikante Wechselwirkung zwischen den beiden Faktoren Abutmentgeometrie und Zement (p<0.002). Während sich bei dem konfektionierten Abutment kaum ein Unterschied zwischen den Zementarten zeigt (p=0.2495, 95%KI [-26.93,7.45]), sind bei dem individuell niedrigen Abutment für den Zement Telio CS höhere Abzugskräfte nötig (p<0.0001, 95%KI [56.15, 98.01]). Dieser Effekt kehrt sich beim hohen Abutment um (p=0.0008, 95%KI [- 66.26,-20.62]). Es ist hier folglich kein einheitlicher Einfluss des Faktors Zement zu beobachten. Ein möglicher Einfluss auf die Retentionskraft, bzw. das Retentionsverhalten von zementierten Zirkoniumdioxid-Suprakonstruktionen auf Implantatabutments bedingt durch verschiedene Abutmentgeometrien wäre denkbar. Als Schlussfolgerung für die Praxis bestätigten sich die gezeigten Vorteile in der Anwendung von modernen semi-permanenten Kompositzementen für die Befestigung CAD/CAM gefertigter vollkeramischer Restaurationen auf Titanabutments, wobei die Indikation bei individuellen Abutmentgeometrien jeweils kritisch zu stellen ist.

Macroscopic properties of rocks are functions of pore-scale geometry and can be determined from laboratory experiments using rock samples. Macroscopic properties can also be determined from computer simulations using 3D pore geometries derived from various imaging techniques. Using 3D imagery and computer simulations, we can calculate the porosity, permeability, formation resistivity factor and cementation exponent in reservoir drill cores. The objective of this thesis was to develop a workflow using Synchrotron X-ray Computed Microtomography (CMT) images and commercially available software in order to determine the macroscopic properties in reservoir drill cores for Midale Marly (M0) and Vuggy Shoal (V6) rocks. The workflow started by using CMT data that provided three-dimensional images of the reservoir rocks taken from drill cores in the Weyburn oil field. The resulting CMT grey scale images were used to isolate the pore space in the rock image. A three-dimensional mesh, representing the pore space, was then used to obtain the solution of the Navier-Stokes equations for an incompressible fluid and Laplace's equation for electrical current flow. Solutions of the Navier-Stokes equations were computed with different inlet pressures for the same pore geometry in order to confirm a direct proportionality between the mass fluid flux and pressure gradient as Darcy’s Law specifies. Previously measured laboratory transport properties were compared with my calculated transport properties on a smaller sub-volume of the same rock core imaged using 0.78 µm resolution CMT images. For the Midale Marly rock, the calculated permeability ranged from 0.01 to 3.53 mD. The formation resistivity factor ranged from 29.3 to 309.43 and the cementation exponent ranged from 1.99 to 2.10. The sample was verified to be nearly isotropic as the permeability was similar for three orthogonal fluid flow directions. Even though the sub-volume analyzed was smaller than a Representative Elementary Volume (REV), the results are within an order of magnitude of the previously calculated laboratory results as completed by Glemser (2007) and fall on the same power law trend. A Vuggy (V6) sample was investigated after the sample had been exposed to CO2, and dissolution within the rock matrix resulted in large visible pore spaces. Using 7.45 µm resolution CMT images, the permeability for a large isolated pore could not be calculated using the previous workflow due to computer memory limitations. Resampling enabled the data to fit into the available computer memory. The permeability values ranged from 2.66x10^5 to 8.59x10^5 mD for resampling the CMT images from 2x to 10x.

The aim of this study was to investigate the removal of cobalt from zinc sulfate solution by cementation with the help of conventional and new type of additives that were 4% Sn-zinc alloy powder and 10% Sn-zinc alloy powder, respectively. Synthetic leach solutions containing 150 g/l Zn and 75 mg/l Co were prepared and used in all of the experiments. The parameters researched with the conventional method were the amount of arsenic trioxide and the effect of copper sulfate on cementation of cobalt. While using the alloys, the parameters studied were the amounts of arsenic trioxide, copper sulfate and tin containing zinc alloy powder additions, cementation duration and temperature. The difference in the optimization of alloy additions was in the amount of addition of arsenic trioxide. The amount of 4%Sn-zinc alloy powder was tried to be optimized with the addition of arsenic trioxide whereas the optimization was tried to be done without any arsenic addition while using 10%Sn-zinc alloy. The XRD and SEM studies of the cementates were also performed. The obtained results indicated that tin containing alloys were much better than pure zinc. With the additions of 4 g/l 4%Sn-Zn alloy dust, 1.2 g/l CuSO4.5H2O, 0.12 g/l As2O3 and in 2 hours of cementation duration at 85-90oC, the maximum amount of cobalt cementation efficiency was achieved. The experiments indicated that cobalt in the solution could be reduced to about 2 mg/l by using 10%Sn-zinc alloy powder with an initial Sn/Co weight ratio of 13.25:1 without the addition of arsenic trioxide at 85oC in 2 hours of cementation duration.

Thesis (M.S.)--University of Alabama at Birmingham, 2007. / Title from first page of PDF file (viewed Feb. 5, 2008). Includes bibliographical references (p. 71-83).

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 6 uppsatser.

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references (leaves 163-170). Also available in electronic version. Access restricted to campus users.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisors: Earle F. McBride and Kitty L. Milliken. Vita. Includes bibliographical references. Also available from UMI.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Includes bibliographical references (p. 278-297). Available also in an electronic version.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2006. / Restricted until October 2007. Bibliography: leaves 182-200. Also available online.

Orientador: Mario Fernando de Goes / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-11T04:18:14Z (GMT). No. of bitstreams: 1 Vaz_RicardoRodrigues_D.pdf: 6222625 bytes, checksum: 52f9da7090d419c4292ce5867fb19956 (MD5) Previous issue date: 2008 / Resumo: O objetivo deste estudo foi avaliar in vitro a resistência e a morfologia da interface da união entre cimentos resinosos e dentina humana. A superfície oclusal de 20 terceiros molares foi removida e a dentina média preparada com lixa 600 de SiC. As restaurações de resina composta indireta (Sinfony) foram confeccionadas em formato circular com 2mm de espessura, jateadas com óxido de alumínio e silanizadas. Os dentes foram divididos em cinco grupos de acordo com a técnica de cimentação: Grupo I ¿ Rely X Unicem/com fotoativação, Grupo II ¿ Rely X ARC/Single Bond 2/com fotoativação, Grupo III ¿ C&B Cement/All Bond 2, Grupo IV ¿ Rely X ARC/Single Bond 2/sem fotoativação e o Grupo V ¿ Rely X Unicem/sem fotoativação. Após a cimentação os conjuntos dente/restauração foram armazenados em água destilada a 37oC por 24 horas e seccionados em formato de palitos com área quadrada de 0.8±0.2mm2 para o ensaio de tração nos tempos de 24 horas e 30 dias utilizando uma máquina de ensaios universal. O tipo de fratura foi observado e classificado em MEV (microscopia eletrônica de varredura). Os resultados foram submetidos à Análise de Variância e ao teste de Tukey para a comparação entre grupos e ao teste-t pareado para comparação entre os tempos de armazenamento de 24 horas e 30 dias (p<0,05). Para análise da morfologia da união em MEV foram obtidos discos de dentina com espessura de 2mm que após a cimentação conforme os grupos experimentais foram seccionados no sentido mesio-distal e incluídos em resina epóxi para os procedimentos de polimento e metalização. Os resultados revelaram que os grupos III, IV e V apresentaram aumento nos valores da resistência da união estatisticamente significantes no período de armazenamento de 30 dias. Os resultados da resistência da união em relação aos modos de polimerização nos tempos de armazenamento de 24 horas e 30 dias revelaram maiores valores na técnica de fotoativação. As análises dos padrões de fratura em MEV mostraram a predominância de fraturas coesivas no cimento para os grupos I e V nos tempos de 24 horas e 30 dias; para o grupo II houve predominância de fraturas mistas sendo coesivas no cimento, na camada híbrida e no adesivo no tempo de 24 horas e fraturas coesivas no cimento no tempo de 30 dias; no grupo III predominou as fraturas coesivas na camada híbrida nos tempos de 24 horas e 30 dias e finalmente para o grupo IV houve predominância de fraturas mistas, sendo coesivas no cimento, na camada híbrida e no adesivo para os tempos de 24 horas e 30 dias. As análises morfológicas das áreas da união não revelaram a formação da camada híbrida para o cimento auto-adesivo Rely X Unicem, enquanto que os cimentos dual Rely X ARC/Single Bond 2 e autopolimerizável C&B Cement/All Bond 2 apresentaram camada híbrida com semelhante morfologia / Abstract: The aim of this study was to evaluate bond strength and the interface morphology between human dentin and resin cements. Oclusal surfaces of 20 third molars were removed and middle dentin was finished with #600 grit SiC. Circular, 2mm thick, indirect composite resin restorations (Sinfony) were made and sandblasted with aluminum oxide and then silanized. Teeth were divided in five groups according to luting technique: Group I ¿ Rely X Unicem/ light-cure; Group II ¿ Rely X ARC/ Single Bond 2/ light-cure; Group III ¿ C& B Cement/ All Bond 2; Group IV ¿ Rely X ARC/ Single Bond 2/ self-cure and Group V ¿ Rely X Unicem/ self-cure. After cementation the teeth/restoration samples were stored in distilled water for 24 hours at 37oC and cut into beam specimens with 0.8±1.0mm2 cross-sections and microtensile tested after 24 and 30 days using a universal testing machine. Fracture patterns were observed and classified by SEM. Results were submitted to ANOVA and Tukey¿s Test to compare groups and pared t-test to compare the storage times of 24hours and 30 days (p<0,05). To analyze interface morphology, 2mm thick flat dentin discs were obtained. After cementation according to the experimental groups the dentin discs were cut vertically and embedded in epoxy resin for the procedures of finishing and gold-sputter. Results revealed that groups III, IV and V presented statistically significant bond strength increase after a storage period of 30 days. Light-cure groups revealed greater bond strength values at the storage times of 24hours and 30 days. SEM fracture pattern evaluation revealed a predominance of cohesive fractures in cement for groups I and V at 24 hours and 30 days. Group II revealed a higher frequency of mixed fractures which were cohesive in cement, hybrid layer and adhesive at 24 hours and cohesive in cement at 30 days. Group III presented more cohesive fractures at the hybrid layer at 24 hours and 30 days while group IV showed a predominance of mixed fractures which were cohesive in cement, hybrid layer and adhesive at 24hours and 30 days. While the morphologic analysis of bonded areas for the self-adhesive cement Rely X Unicem did not reveal the formation of a hybrid layer, the dual-cure cement Rely X ARC/Single Bond 2 and the self-cure cement C&B Cement/All Bond 2 presented hybrid layers with similar morphology / Doutorado / Materiais Dentarios