Thesis (M.S.)--University of Michigan, Ann Arbor, 1962. / Typescript (photocopy). eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 65-66).

Indiana University-Purdue University Indianapolis (IUPUI) / Background and Rationale: As compared with glass-based ceramics, zirconia has gained considerable popularity in restorative dentistry due to its superior mechanical properties. Clinically, however, zirconia ceramics pose a significant challenge regarding the achievement of a reliable and durable bond to resin-based cements. Thus far, it has been established that zirconia bond to resin-based cements can be enhanced after different surface conditioning methods, such as airborne particle abrasion with aluminum oxide particles. Meanwhile, another major issue pertaining to bonding of ceramic restorations is related to its potential contamination before cementation. Briefly, after sandblasting and clinical try-in procedures, zirconia can be contaminated with saliva and/or blood. As with many metals, zirconium shows a strong affinity towards the phosphate group found in saliva and other fluids, which reacts with the zirconia surface and makes bonding very difficult. Recently, a new cleaning agent called Ivoclean® (Ivoclar-Vivadent), which is an alkaline suspension of zirconium oxide particles, has been introduced in the market to remove contamination from zirconia in an effort to improve bonding to resin cements. Objective: The purpose of this study was to evaluate the influence of saliva contamination and the effect of several cleaning methods, including Ivoclean on resin bond strength to zirconia. Materials and Methods: Eighty square-shaped specimens (ϕ = 12 mm x 12 mm x 3 mm) of yttria-stabilized full-contour zirconia (Diazir®, Ivoclar-Vivadent, Amherst, NY) were sectioned from zirconia blocks using a water-cooled diamond blade. Then, these specimens were embedded in acrylic resin, and their surfaces gradually finished with silicon carbide papers (600 grit to 1200 grit). The prepared zirconia surfaces were sandblasted with 50-μm aluminum oxide particles for 15 s, under 2.5 bars and from distance of 10 mm. After sandblasting the specimens were cleaned in an ultrasonic bath containing distilled water for 5 min and air-dried for 10s. All samples were equally divided into 4 groups (n = 20) according to the cleaning method. Airborne particle abraded specimens without contamination was served as the control group. Remaining groups were contaminated with saliva, and subjected to different cleaning protocols, namely: Ivoclean®, 70% isopropanol, and no treatment. Two resin cement buttons (Multilink – Ivoclar-Vivadent, Amherst, NY) were built over each zirconia surface and light-cured following the manufacturer recommendations. The influence of contamination and surface cleaning methods on ceramic bond durability were examined after 24 h on half of the samples in each group (n = 10, n = 20), and the other half (n = 10, n = 20) specimens will undergo 6000 thermocycles (TC) before shear bond testing in the universal testing machine. Conclusion of Expected Outcomes: The shear bond strength of resin cement to zirconia led to a significant improvement after cleaning with Ivoclean both immediately and after thermal aging.

A confecção de uma prótese parcial removível exige a correta determinação do eixo de inserção e, consequentemente, o preparo cuidadoso de planos guias para satisfazer os princípios de retenção e estabilidade. Entretanto, grande parte dos profissionais negligencia esta etapa, seja por desconhecimento de sua importância, dificuldade técnica, quantidade limitada de opções cientificamente comprovadas de seus resultados, ou pela aparente e ilusória economia de tempo e de trabalho que sua realização possa tomar. Então, em função do número limitado de técnicas eficientes para transferência de planos guias e da necessidade de um método que otimize o tempo dos profissionais de forma prática e didática, o presente estudo buscou introduzir uma nova maneira de transferir os planos guias. A nova técnica consiste na utilização de uma placa de vacuum-form (PV), comparando-a com preparos realizados em delineador e com duas outras técnicas pré-existentes: à mão livre (ML) e coroas-guia (CG), analisando sua eficácia e precisão. Réplicas idênticas (n=44) de um modelo de gesso representativo da arcada inferior foram divididas em 11 grupos, com 4 modelos cada. Cada um dos onze estudantes de Odontologia recebeu 4 modelos - em um deles os planos guias já tinham sido previamente preparados com delineador, os quais serviram apenas de referência para que fossem empregados os outros métodos. As diferenças angulares dos planos guias nos 44 modelos, nos sentidos ântero-posterior, látero-lateral e cruzado foram mensuradas por meio de uma máquina de medição por coordenadas. A análise de variância para medidas repetidas e o Teste de Comparações Múltiplas (método de Tukey) revelaram que tanto no sentido látero-lateral, como na avaliação cruzada, houve diferença significativa na média dos preparos feitos no delineador em relação a todas as outras técnicas. No entanto, não foram identificadas diferenças importantes entre os três métodos. Para a avaliação ântero-posterior, verificou-se diferença relevante somente entre os preparos feitos no delineador e CG, o que não foi detectado entre ML, PV e delineador. Observou-se também, que os preparos obtidos com delineador apresentaram variações angulares próximos de zero, indicando paralelismo quase absoluto e que os planos guias preparados nesse dispositivo demonstraram média e variabilidade menores que os outros métodos. As demais técnicas (ML, CG e PV) se comportaram de forma estatistica semelhante, exceto no sentido ântero-posterior, onde a CG apresentou maior variação angular. Concluiu-se que a técnica proposta apresentou resultados satisfatórios em relação aos padrões adotados neste estudo, quando comparada às demais técnicas e ao delineador. Portanto, a mesma pode ser considerada viável, já que sua utilização oferece uma confecção de próteses removíveis de forma mais criteriosa, atendendo às necessidades profissionais, em termos de facilidade e tempo gasto em sua execução. / The confection of a removable partial denture requires accurate determination of the path of insertion and consequently, the careful preparation of guide planes to meet the principles of retention and stability. However, a great number of professionals neglect this step because of unconsciousness of its importance, or technical difficulty, or limited options of techniques or because of apparent and illusory saving of time and work. Due to the limited number of proven effective techniques for guide planes preparation and the need of an effective method for optimizing time of dental surgeons in a clear and practical way, this present study aimed the introduction of a new technique for transferring guide planes. The new technique consists on the use of a vacuum form splint (VF). To measure its efficiency and accuracy it was compared with the preparations carried out in a dental surveyor and with two other pre-existing techniques: freehand (FH) and acrylic resin guide crown (GC). Identical replicas (n=44) of a gypsum model representing a dental lower arch were divided into 11 groups of four. Each of the eleven dental students received four models - in one of the models, the guide planes were previously prepared with the surveyor to be used as a reference for the application of the three transfer techniques in the other three remaining models. The angular differences of the the prepared guide planes on the 44 models were measured by a coordinate measuring machine in the anteroposterior, laterolateral and crossed views. The Analysis of Variance and Tukey method revealed that, for the laterolateral evaluation and crossed evaluation, significant differences were found in the average of the preparations obtained by the surveyor in relation to all other techniques. There were no significant differences among the three techniques. Anteroposterior evaluation showed significant difference between the average of the preparations made by the surveyor and by the GC, which was not observed between the FH and PV groups compared to the surveyor. It was also found that the angular variation obtained by preparations using the surveyor was close to zero degree, indicating almost absolute parallelism. The FH, GC and VF techniques were statistically similar, except for the anteroposterior evaluation. In the anteroposterior evaluation the GC presented higher angular variation. It was concluded that the proposed technique showed satisfactory results concerning the adopted standards in the present study when compared with the preparations made by other techniques and the surveyor. Thus, the VF technique can be considered viable, since it improves the quality of the Removable Partial Denture and meets the professional needs, saving time in the procedures.

A confecção de uma prótese parcial removível exige a correta determinação do eixo de inserção e, consequentemente, o preparo cuidadoso de planos guias para satisfazer os princípios de retenção e estabilidade. Entretanto, grande parte dos profissionais negligencia esta etapa, seja por desconhecimento de sua importância, dificuldade técnica, quantidade limitada de opções cientificamente comprovadas de seus resultados, ou pela aparente e ilusória economia de tempo e de trabalho que sua realização possa tomar. Então, em função do número limitado de técnicas eficientes para transferência de planos guias e da necessidade de um método que otimize o tempo dos profissionais de forma prática e didática, o presente estudo buscou introduzir uma nova maneira de transferir os planos guias. A nova técnica consiste na utilização de uma placa de vacuum-form (PV), comparando-a com preparos realizados em delineador e com duas outras técnicas pré-existentes: à mão livre (ML) e coroas-guia (CG), analisando sua eficácia e precisão. Réplicas idênticas (n=44) de um modelo de gesso representativo da arcada inferior foram divididas em 11 grupos, com 4 modelos cada. Cada um dos onze estudantes de Odontologia recebeu 4 modelos - em um deles os planos guias já tinham sido previamente preparados com delineador, os quais serviram apenas de referência para que fossem empregados os outros métodos. As diferenças angulares dos planos guias nos 44 modelos, nos sentidos ântero-posterior, látero-lateral e cruzado foram mensuradas por meio de uma máquina de medição por coordenadas. A análise de variância para medidas repetidas e o Teste de Comparações Múltiplas (método de Tukey) revelaram que tanto no sentido látero-lateral, como na avaliação cruzada, houve diferença significativa na média dos preparos feitos no delineador em relação a todas as outras técnicas. No entanto, não foram identificadas diferenças importantes entre os três métodos. Para a avaliação ântero-posterior, verificou-se diferença relevante somente entre os preparos feitos no delineador e CG, o que não foi detectado entre ML, PV e delineador. Observou-se também, que os preparos obtidos com delineador apresentaram variações angulares próximos de zero, indicando paralelismo quase absoluto e que os planos guias preparados nesse dispositivo demonstraram média e variabilidade menores que os outros métodos. As demais técnicas (ML, CG e PV) se comportaram de forma estatistica semelhante, exceto no sentido ântero-posterior, onde a CG apresentou maior variação angular. Concluiu-se que a técnica proposta apresentou resultados satisfatórios em relação aos padrões adotados neste estudo, quando comparada às demais técnicas e ao delineador. Portanto, a mesma pode ser considerada viável, já que sua utilização oferece uma confecção de próteses removíveis de forma mais criteriosa, atendendo às necessidades profissionais, em termos de facilidade e tempo gasto em sua execução. / The confection of a removable partial denture requires accurate determination of the path of insertion and consequently, the careful preparation of guide planes to meet the principles of retention and stability. However, a great number of professionals neglect this step because of unconsciousness of its importance, or technical difficulty, or limited options of techniques or because of apparent and illusory saving of time and work. Due to the limited number of proven effective techniques for guide planes preparation and the need of an effective method for optimizing time of dental surgeons in a clear and practical way, this present study aimed the introduction of a new technique for transferring guide planes. The new technique consists on the use of a vacuum form splint (VF). To measure its efficiency and accuracy it was compared with the preparations carried out in a dental surveyor and with two other pre-existing techniques: freehand (FH) and acrylic resin guide crown (GC). Identical replicas (n=44) of a gypsum model representing a dental lower arch were divided into 11 groups of four. Each of the eleven dental students received four models - in one of the models, the guide planes were previously prepared with the surveyor to be used as a reference for the application of the three transfer techniques in the other three remaining models. The angular differences of the the prepared guide planes on the 44 models were measured by a coordinate measuring machine in the anteroposterior, laterolateral and crossed views. The Analysis of Variance and Tukey method revealed that, for the laterolateral evaluation and crossed evaluation, significant differences were found in the average of the preparations obtained by the surveyor in relation to all other techniques. There were no significant differences among the three techniques. Anteroposterior evaluation showed significant difference between the average of the preparations made by the surveyor and by the GC, which was not observed between the FH and PV groups compared to the surveyor. It was also found that the angular variation obtained by preparations using the surveyor was close to zero degree, indicating almost absolute parallelism. The FH, GC and VF techniques were statistically similar, except for the anteroposterior evaluation. In the anteroposterior evaluation the GC presented higher angular variation. It was concluded that the proposed technique showed satisfactory results concerning the adopted standards in the present study when compared with the preparations made by other techniques and the surveyor. Thus, the VF technique can be considered viable, since it improves the quality of the Removable Partial Denture and meets the professional needs, saving time in the procedures.