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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Large-Scale Testing of Passive Force Behavior for Skewed Bridge Abutments with Gravel and Geosynthetic Reinforced Soil (GRS) Backfills

Fredrickson, Amy 01 July 2015 (has links) (PDF)
Correct understanding of passive force behavior is particularly key to lateral evaluations of bridges because plastic deformation of soil backfill is vital to dissipation of earthquake energy and thermally-induced stresses in abutments. Only recently have studies investigated the effects of skew on passive force. Numerical modeling and a handful of skewed abutment tests performed in sand backfill have found reduced passive force with increasing skew, but previous to this study no skewed tests had been performed in gravel or Geosynthetic Reinforced Soil (GRS) backfills. The goal of this study was to better understand passive force behavior in non-skewed and skewed abutments with gravel and GRS backfills. Prior to this study, passive pressures in a GRS integrated approach had not been investigated. Gravel backfills also lack extensive passive force tests.Large-scale testing was performed with non-skewed and 30° skewed abutment configurations. Two tests were performed at each skew angle, one with unconfined gravel backfill and one with GRS backfill, for a total of four tests. The test abutment backwall was 11 ft (3.35 m) wide, non-skewed, and 5.5 ft (1.68 m) high and loaded laterally into the backfill. However, due to actuator loading constraints, all tests except the non-skewed unconfined gravel test were performed to a backfill height of 3.5 ft (1.07 m). The passive force results for the unconfined gravel test was scaled to a 3.5 ft (1.07 m) height for comparison.Test results in both sets of backfills confirmed previous findings that there is significant reduction in passive force with skewed abutment configurations. The reduction factor was 0.58 for the gravel backfill and 0.63 for the GRS backfill, compared to the predicted reduction factor of 0.53 for a 30° skew. These results are within the scatter of previous skewed testing, but could indicate that slightly higher reduction factors may be applicable for gravel backfills. Both backfills exhibited greater passive strength than sand backfills due to increased internal friction angle and unit weight. The GRS backfill had reduced initial stiffness and only reached 79% to 87% of the passive force developed by the unreinforced gravel backfill. This reduction was considered to be a result of reduced interface friction due to the geotextile. Additionally, the GRS behaved more linearly than unreinforced soil. This backfill elasticity is favorable in the GRS-Integrated Bridge System (GRS-IBS) abutment configuration because it allows thermal movement without developing excessive induced stresses in the bridge superstructure.
22

Life Cycle Assessment on Bridge Abutments : Automated Design in Structural Enginee

Lekkas, Sotirios January 2019 (has links)
Life Cycle Assessment (LCA) is the globally the most recognised method for quantifying theimpact the a product or service has on the environment through its whole life-span. Theconstruction sector plays a key role in the depletion of the natural resources and the energyconsumption on the planet. Thus it is fundamental that an environmental assessment tool likeLCA should be in close cooperation with the construction process.This thesis focuses on the environmental impact of bridge abutments, and can be divided in twoparts.The rst one focuses on enhancing the automated design in the construction eld. A Python codeis created that focuses on creating the geometry of any type of bridge abutment and conductingthe calculations for the required concrete and reinforcement. The process is attempted to becomecompletely automated.The second part introduces three alternative designs for a bridge abutment that attempt to havethe same structural properties and cooperate successfully with the superstructure, while at thesame time utilize as little material as possible. The possible reduction in material is quantiedin environmental terms after an environmental impact assessment is performed.The results show that dierent designs can have a great impact on the reduction on the materialconsumption and on the impact that the whole structure has on the environment. The resultsin this study might provide the designers with valuable motivation and guidelines to achievehigher sustainability standards in the future.
23

Avaliação da infiltração microbiana na interface implante-abutment em conexões tipo hexágono interno e cone-morse de implantes osseointegráveis / Evaluation of bacterial leakage at implant abutment interfaces of implants wiht internal hexagonal

SANTANA, Washington Macedo de 28 September 2007 (has links)
Made available in DSpace on 2014-07-29T15:21:59Z (GMT). No. of bitstreams: 1 Dissertacao Washington M de Santana.pdf: 773538 bytes, checksum: 8a934007fd255f4536cfdfdbde213eb7 (MD5) Previous issue date: 2007-09-28 / The scientific literature has reported that dental implants can be affected by the oral microorganisms through the formation of a bacterial biofilm. The region most affected is the connection between the implant platform and the prosthetic abutment, particularly in implants with an external connection. Therefore, the region of the implant/abutment connection can participate in the development of peri-mucositis or peri-implantitis. They propose that these implant/abutment connections known as morse taper provide an effective seal against microorganisms. Thus the objective of this research was to evaluate the microleakage on the implant/abutment interface of internal hex and morse taper prosthetic connections. Thirty five (35) implants were selected and divided into seven (7) groups (5 groups of implants from Brazilian manufacturers and 2 groups of implants manufactured abroad). The tested implants were Straumann (Straumann AG® / Switzerland), Ankylos (Dentsply-Friadent® / Germany), AR Morse (Conexão/Sistema de Prótese® São Paulo-SP), Titamax CM (Neodent® /Curitiba-PR), Titamax II Plus (Neodent®/Curitiba-PR), Stronger (Sin/Sistema Nacional de Implante® São Paulo - SP) e Titanium Fix CM (AS Technology / São José dos Campos-SP). For the microbiological test the bacterium Enterococus faecalis (ATCC 29212) was selected. This bacterium was inoculated in the interior aspect of the implant followed by immediate installation and final torque (N/cm) of the prosthetic abutment. The implant/abutment set up was then placed in a Brain Heart Infusion broth (BHI) and incubated in this broth for 14 days. During this period, the cloudiness of the broth was evaluated at days 7 and 14. The data were statistically analyzed by the Kruskal Wallis method. The results demonstrated that all samples from both Ankylos and Neodent CM groups did not present microleakage. Although 20% of samples from Conexao AR Morse group presented microleakage, there was no significant statistical difference when compared to the former two groups. Furthermore, all samples from Straumann,Titanium Fix CM, Neodent Titamax II Plus, and SIN Strong groups presented microleakage after 14 days of culture (p=0.05), though correlation analysis among these samples did not reveal significant statistical differences. / A literatura tem ressaltado que os implantes osseointegráveis podem ser afetados por transtornos decorrentes da formação de biofilme bacteriano em sua superfície. A região acometida envolve principalmente a conexão entre a plataforma do implante e o abutment, situação evidenciada especialmente nos implantes de conexões externas. Assim, tal situação pode culminar na formação de mucosites ou até mesmo perimplantites. Alguns tipos de conexões têm sido colocados no mercado pelos fabricantes de implantes com proposta de melhor selamento microbiológico. Baseada nesta consideração, esta pesquisa teve como propósito avaliar a microinfiltração na interface implante-abutment das conexões protéticas de alguns sistemas de hexágono interno e das conexões internas conemorse, que propõem capacidade efetiva de vedamento microbiológico. Para sua execução foram selecionados 35 implantes divididos em 7 grupos (5 grupos de implantes de procedência de empresas nacionais e 2 grupos advindos de empresas importadas). Os implantes analizados foram Straumann (Straumann AG® / Switzerland) e Ankylos (Dentsply-Friadent® / Germany), AR Morse (Conexão/Sistema de Prótese® São Paulo-SP), Titamax CM (Neodent® /Curitiba-PR), Titamax II Plus (Neodent®/Curitiba-PR), Stronger (Sin/Sistema Nacional de Implante® São Paulo - SP) e Titanium Fix CM (AS Technology / São José dos Campos-SP). Para os testes de contaminação, foi selecionada a bactéria Enterococcus faecalis (ATCC 29212), sendo esta inoculada no interior do implante com a imediata instalação e torque (N/cm) do respectivo abutment (pilar protético). Posteriormente, o conjunto pilar/implante inoculado foi colocado em meio de cultura caldo infusão de cérebro e coração (BHI) e mantido neste meio por um período de 14 dias. Durante este período, o controle da contaminação indicando microinfiltração foi feito pelo turvamento do meio de cultura, avaliado aos 7 dias e aos 14 dias após inoculação. Após a coleta dos dados, foi aplicado teste estatístico pelo método não paramétrico de Kruskal- Wallis e os resultados demonstraram que todas as amostras do grupo Ankylos e Neodent CM não apresentaram microinfiltração, sendo que 20% do grupo Conexão AR Morse apresentaram microinfiltração, contudo sem apresentar diferenças estatísticas significativas quando comparados com os grupos anteriores. Ainda, as amostras dos grupos Straumann, Titanium-Fix CM, Neodent Titamax II Plus e SIN Strong apresentaram todas as amostras infiltradas após 14 dias do estudo (nível de significância alfa=0,05) e na avaliação da correlação entre estas amostras, constatou-se que não houve diferenças estatísticas significativas entre si.
24

Passive Force on Skewed Abutments with Mechanically Stabilized Earth (MSE) Wingwalls Based on Large-Scale Tests

Franke, Bryan William 18 March 2013 (has links) (PDF)
Passive force-deflection behavior for densely compacted backfills must be considered in bridge design to ensure adequate resistance to both seismic and thermally induced forces. Current codes and practices do not distinguish between skewed and non-skewed bridge abutment geometries; however, in recent years, numerical models and small-scale, plane-strain laboratory tests have suggested a significant reduction in passive force for skewed bridge abutments. Also, various case studies have suggested higher soil stresses might be experienced on the acute side of the skew angle. For these reasons, three large-scale tests were performed with abutment skew angles of 0, 15 and 30 degrees using an existing pile cap [11-ft (3.35-m) wide by 15-ft (4.57-m) long by 5.5-ft (1.68-m) high] and densely compacted sand backfill confined by MSE wingwalls. These tests showed a significant reduction in passive force (approximately 38% as a result of the 15 degree skew angle and 51% as a result of the 30° skew angle. The maximum passive force was achieved at a deflection of approximately 5% of the backwall height; however, a substantial loss in the rate of strength gain was observed at a deflection of approximately 3% of the backwall height for the 15° and 30° skew tests. Additionally, the soil stiffness appears to be largely unaffected by skew angle for small displacements. These results correlate very well with data available from numerical modeling and small-scale lab tests. Maximum vertical backfill displacement and maximum soil pressure measured normal to the skewed backwall face were located on the acute side of the skew for the 15° and 30° skew test. This observation appears to be consistent with observations made in various case studies for skewed bridge abutments. Also, the maximum outward displacement of the MSE wingwalls was located on the obtuse side of the skew. These findings suggest that changes should be made to current codes and practices to properly account for skew angle in bridge design.
25

Investigation into the Dosimetric Effects of Abutting Multi-Leaf-Collimated Photon Fields with Extended Source-to-Surface Electron Fields

STEEL, Jared Gary January 2007 (has links)
This thesis reports on the findings of an investigation into the dosimetry resulting from the abutment of en face 6 MeV electron and 6 MV photon beams as applied to the clinical challenge of radiation therapy treatments to head and neck cancer sites. Particular concern is given to the use of multi-leaf collimator (MLC) technology for photon beam definition when abutted to extended source-to-surface (SSD) electron beams. We made dosimetric comparison between MLC and Cerrobend® shielding for use in an abutment situation. The effects of extending the SSD of the electron beam were also assessed. We checked the ability of a Pinnacle3 v7.6 treatment planning system (TPS) to correctly model the dosimetry resulting from this extended electron beam SSD. Volumetric simulations of composite dosimetry resulting in water were conducted in MATLAB® for variations of surface abutment gap, and photon beam shielding type and angle. Visualization Toolkit (VTK) script was developed to visualise the resulting dosimetry. The effect of extending the SSD of the electron beam increases the beam penumbra significantly, exacerbating the challenge of matching this field to a photon beam edge. Furthermore, the TPS was shown to inaccurately model the electron beam penumbra for the extended SSD conditions. The employment of MLC shielding provides for some advantages over Cerrobend® in terms of overall composite hotspot volumes and coldspot magnitudes, though introduces detrimental dosimetric inhomogeneities in the underlying volume. Distinctly, no combination of abutment gap and shielding variables resulted in dosimetry in the range of 90% to 110% at the depth of dmax for the beam energies considered here. We provided tabulated data across these variables to outline the trade-offs present, and aid clinical decisions regarding this challenging dosimetric
26

Análise fotoelástica da distribuição de tensões em prótese fixa unitária posterior com conexões hexágono externo, hexágono interno e cone morse / Photoelastic stress analysis for implant-supported single fixed posterior crowns with external hexagon, internal hexagon and morse taper implant/abutment connections

González Esquerra, Martha Margarita 28 November 2014 (has links)
O objetivo deste estudo foi avaliar a distribuição de tensões na região peri-implantar de próteses fixas unitárias cimentadas com conexões protéticas em hexágono externo (HE), hexágono interno (HI) e cone morse (CM), substituindo o 2° pré-molar mandibular; utilizando análise fotoelástica. Foram confeccionados 3 modelos fotoelásticos com implantes de diferentes conexões protéticas (HE, HI e CM) suportando coroas metalocerâmicas unitárias, com dentes adjacentes (1° molar e 1° pré-molar mandibular). Foram aplicados 2 tipos de cargas com diferentes intensidades, oclusal fisiológica (15, 20 e 25 Kgf) e pontual (10 e 15 Kgf) na fossa mesial das coroas implantossuportadas. As imagens obtidas foram inseridas no programa Fringes® (Laboratório de Projetos Mecânicos, Universidade Federal de Uberlândia, Uberlândia, Brasil), e selecionados 12 pontos a serem analisados. Foram realizadas análises quantitativa e qualitativa das tensões observadas. Os resultados das tensões (KPa) medias da região peri-implantar, para cada tipo e intensidade de carga, foram: Cargas fisiológicas: 1) 15 Kgf: HE 107,42; HI 88,81; CM 182,63; 2) 20 Kgf: HE 185,60; HI 123,77; CM 226,44; e 3) 25 Kgf: HE 207,90; HI 176,88; CM 320,65; Cargas pontuais: 1) 10 Kgf: HE 115,94; HI 108,14; CM 64,78; e 2) 15 Kgf: HE 147,25; HI 143,88; CM 177,87. Foi observado que para os carregamentos fisiológicos a HI apresentou os menores valores de tensão e melhor distribuição entre implante e dentes adjacentes; a CM apresentou os maiores valores de tensão, contudo a distribuição entre implante e dentes adjacentes também foi adequada; a HE mostrou a distribuição menos favorável com tensões na crista mesial do implante. Nos carregamentos pontuais a CM apresentou melhor distribuição de tensões ao longo do implante seguido pela HI e HE. Conclui-se que a distribuição de tensões foi influenciada pelo tipo de conexão protética; sendo que as tensões foram melhor distribuídas na carga oclusal fisiológica. O HI apresentou melhor distribuição de tensões para a carga fisiológica e o CM para a carga pontual, evidenciando melhor desempenho das conexões internas / This study aimed to evaluate the peri-implant stress fields generated from 3 different implant- abutment interfaces external hexagon (EH), internal hexagon (IH) and morse taper (MT); supporting single crowns corresponding to the 2nd mandibular pré-molar via photoelastic analysis. 3 photoelastic models with different implant-abutment connections (HE, HI, CM) supporting metal-ceramic single crowns with adjacent teeth (mandibular 1st molar and 2nd pre-molar) were fabricated. The models were submitted to different loads: physiologic occlusion (15, 20, 25Kgf) and punctual (10, 15Kgf) in the implant-supported crown at the mesial fossa region. The images obtained were inserted in the software Fringes® (Laboratório de Projetos Mecânicos, Universidade Federal de Uberlândia, Uberlândia, Brasil). The maximum stresses were determined and observed at 12 selected points, qualitative and quantitative analysis were performed. The results of the stress (KPa) average of peri-implant regions with the 2 different loads and their respective intensities (Kgf) were: Physiologic occlusion: 1) 15 Kgf: HE 107,42; HI 88,81; CM 182,63; 2) 20 Kgf: HE 185,60; HI 123,77; CM 226,44; and 3) 25 Kgf: HE 207,90; HI 176,88; CM 320,65; Punctual loads: 1) 10 Kgf: HE 115,94; HI 108,14; CM 64,78; and 2) 15 Kgf: HE 147,25; HI 143,88; CM 177,87. With the physiological load the IH showed the lowest stress values and a favorable distribution among implant and adjacent teeth; the MT showed the highest stress values, however a favorable distribution with the adjacent teeth; the EH showed stress values in the cervical mesial point of the implant. For the punctual load the MT showed the best stress distribution within the implant, followed by the IH and EH. It was concluded that stress patterns were influenced by the connection design and were more favorable with the physiological occlusion load for all connections. The IH showed better stress distribution with the physiological occlusion load and the MT with the punctual load, showing better performance for internal connections
27

Effect of CAD/CAM abutment height and cement type on the retention of zirconia crowns / Efeito da altura do pilar CAD / CAM e tipo de cimento na retenção de coroas de zircônia

Silva, Camila Perfeito Evangelista da 07 May 2018 (has links)
Aim: To evaluate the effect of different Ti-base abutment heights and cement type on the pullout retention of zirconia-based restorations. Methods: Identical crowns were designed in a CAD software to fit two different Tibase abutment heights, as follows (n=10/group): (i) 4-mm-height Ti-base abutment (Tall), and (ii) 2.5-mm-height Ti-base abutment (Short). Four cement types were selected: (i) Temporary cement (Provisional); (ii) Glass-ionomer cement (Meron); (iii) self-adhesive resin cement (U200), and (iv) conventional resin cement (Ultimate) with universal adhesive for treatment of titanium and zirconia substrates. Pull-out testing was performed in a universal testing machine. Data were statistically evaluated through two-way analysis of variance following post-hoc comparisons by Tukey test. Results: Tall Ti-base abutments demonstrated similar retention to short abutments when data is collapsed over cement (p>0.74). Data evaluation as a function of cement type demonstrated the superiority of resin-based cements relative to provisional and glass-ionomer groups (p<0.01). Retentiveness data as a function of both factors demonstrated similar force to dislodgment between tall and short abutments for all within cement comparisons (p>0.42), except for U200 (p=0.032). Also, tall abutments cemented with Ultimate evidenced higher pull out values than U200 (p=0.043), and both were significantly more retentive than tall provisional and meron (p<0.001). No significant difference was observed between U200 and Ultimate cements for short abutments (p=0.758), and both presented statistically higher pullout values than provisional and glass-ionomer (p=0.001). Conclusions: While Ti-base abutment height have not influenced zirconia superstructure retentiveness, resin-based cements significantly evidenced higher retention than glass ionomer and temporary cements. / Objetivo: Avaliar o efeito de diferentes alturas de interface de Titânio (Ti) e diferentes tipos de cimento na retenção de coroas de zircônia. Métodos: Coroas idênticas foram projetadas em um software de CAD capaz de adaptar duas alturas diferentes do pilar de interface de Ti: cada grupo foi composto de 10 amostras conforme se segue: (i) interface de Ti de 4 mm de altura (alto) e (ii) interface de 2,5 mm de altura (curto). Foram selecionados quatro tipos de cimento: (i) cimento temporário (Provisional); (ii) Cimento de ionômero de vidro (Meron); (iii) cimento resinoso auto-adesivo (U200) e (iv) cimento resinoso convencional (Ultimate) com adesivo universal para tratamento de substratos de titânio e zircônia. O teste de tração foi realizado em uma máquina de ensaio universal. Os dados foram avaliados estatisticamente através de análise de variância a dois critérios, após comparações pós-hoc pelo teste de Tukey. Resultados: As interfaces de Ti demonstraram retenção semelhante aos pilares curtos quando os dados foram colapsados sobre o cimento (p> 0,74). A avaliação dos dados em função do tipo de cimento demonstrou a superioridade dos cimentos à base de resina em relação aos grupos de cimentos temporário e de ionômero de vidro (p <0,01). Os dados de retenção em função de ambos os fatores demonstraram força semelhante ao deslocamento, entre pilares altos e curtos, para todos dentro das comparações de cimento (p> 0,42), exceto para U200 (p = 0,032). Além disso, os pilares altos cimentados com Ultimate evidenciaram maiores valores de tração do que os cimentados com U200 (p = 0,043), e ambos foram significativamente mais retentivos do que o pilar alto cimentado com cimento Provisional e o Meron (p <0,001). Não foi observada diferença significativa entre os cimentos U200 e Ultimate para pilares curtos (p = 0,758) e ambos apresentaram valores de tração estatisticamente mais elevados que os cimentos de ionômero de vidro e cimento temporário (p = 0,001). Conclusões: Embora a altura da interface de Ti não tenha influenciado a retenção das coroas de zircônia, os cimentos resinosos resultaram em maior retenção do que o ionômero de vidro e cimentos temporários.
28

Resistência à tração entre componentes de pilar híbrido Conexão® submetido a teste de fadiga termomecânica / Tension strength between the two pieces of the hybrid abutment Conexão® after thermomechanical fatigue test

Bonachela, Clara Fassoni 21 September 2018 (has links)
Os pilares de próteses sobre implantes são determinantes para o sucesso final da restauração. Dentre os mais variados disponíveis no mercado, os pilares híbridos são uma proposta atual que propõe associar otimização da estética com performance biomecânica de qualidade à longo prazo. Sendo assim, o objetivo desse estudo foi verificar a resistência à tração entre os componentes do pilar híbrido parafusado Precision Link® (Conexão®) após ensaio de fadiga térmica e mecânica, através de uma metodologia inovadora proposta pelos autores. Foram utilizados 33 Conjuntos Precision Link 3,5 NP + Coping de Zircônia Base para Acrescentar 3,5 (Conexão), distribuídos em 3 grupos de 11 espécimes, nomeados de acordo com o número de ciclos mecânicos aos quais foram submetidos durante o teste de fadiga (Grupo Controle [G CONTROLE], Grupo de 240 000 ciclos [G1] e Grupo de 480 000 ciclos [G2]). Após o ensaio de fadiga termomecânica, os pilares foram submetidos a teste de tração, por meio de um dispositivo desenvolvido exclusivamente para esse trabalho, adaptado em uma máquina de ensaios universal. Os dados de resistência a tração foram submetidos à análise estatística através da análise de variância a 1 critério e Teste de Tukey para comparações individuais, mediante à qual foi identificada diferença estatisticamente significativa entre G1 e G CONTROLE e G1 e G2, tendo G1 demonstrado valores de resistência a tração menores que os outros grupos (Valores médios: G CONTROLE= 58,172 N, G1= 46,181 N, G2= 64,725 N). Pode-se concluir que a metodologia proposta para esse estudo, com o desenvolvimento de um dispositivo específico de tração é efetiva para identificar os valores de resistência à tração dos componentes de pilares híbridos parafusados Precision Link® (Conexão®) e a exposição aos ciclos termomecânicos testados no ensaio de fadiga influencia nos valores de tração entre os mesmos, primeiro diminuindo-os e depois aumentando-os de volta possivelmente por conta do fenômeno de degradação em baixa temperatura nos componentes de zircônia. / Implant abutments have a key role in the success of dental reabilitations. Among other options, hybrid abutments are a new option that can associate esthetic achievements with efficient long-term biomechanical performance. The purpose of this study was to verify the tension strenght between the components of the screw-retained hybrid abutment Precision Link® (Conexão®) after thermomechanical fatigue test, using an innovative approach. Thirty-three samples of Precision Link (d)3,5 NP + Zirconia Coping Add Base (d)3,5 (Conexão) were divided in three groups of eleven specimens each. The groups were divided by the number of mechanical cycles (Control Group [CONTROL G], Group of 240 000 cycles [G1] and Group of 480 000 cycles [G2]). After the thermomechanical fatigue test, the abutments were submitted to a tension strenght test in a specific device designed by the authors for this study. The referred device was coupled to an universal testing machine. Statistic analysis (ANOVA-1 e Tukey Test) showed G1 had statistical significative lower values of tension strenght than CONTROL G and also than G2. (Mean values: CONTROL G= 58,172 N, G1= 46,181 N, G2= 64,725 N) In conclusion, the methodology proposed for this study was effective in identifying the tension strenght values between the components of the screw-retained hybrid abutment Precision Link® (Conexão®). Also, the thermomechanical fatigue test influenced in the tension strenght values, first reducing the values of tension strenght, then increasing them back, by the transformation of phase of zirconia exposed to a wet environement.
29

Análise fotoelástica da distribuição de tensões em prótese fixa unitária posterior com conexões hexágono externo, hexágono interno e cone morse / Photoelastic stress analysis for implant-supported single fixed posterior crowns with external hexagon, internal hexagon and morse taper implant/abutment connections

Martha Margarita González Esquerra 28 November 2014 (has links)
O objetivo deste estudo foi avaliar a distribuição de tensões na região peri-implantar de próteses fixas unitárias cimentadas com conexões protéticas em hexágono externo (HE), hexágono interno (HI) e cone morse (CM), substituindo o 2° pré-molar mandibular; utilizando análise fotoelástica. Foram confeccionados 3 modelos fotoelásticos com implantes de diferentes conexões protéticas (HE, HI e CM) suportando coroas metalocerâmicas unitárias, com dentes adjacentes (1° molar e 1° pré-molar mandibular). Foram aplicados 2 tipos de cargas com diferentes intensidades, oclusal fisiológica (15, 20 e 25 Kgf) e pontual (10 e 15 Kgf) na fossa mesial das coroas implantossuportadas. As imagens obtidas foram inseridas no programa Fringes® (Laboratório de Projetos Mecânicos, Universidade Federal de Uberlândia, Uberlândia, Brasil), e selecionados 12 pontos a serem analisados. Foram realizadas análises quantitativa e qualitativa das tensões observadas. Os resultados das tensões (KPa) medias da região peri-implantar, para cada tipo e intensidade de carga, foram: Cargas fisiológicas: 1) 15 Kgf: HE 107,42; HI 88,81; CM 182,63; 2) 20 Kgf: HE 185,60; HI 123,77; CM 226,44; e 3) 25 Kgf: HE 207,90; HI 176,88; CM 320,65; Cargas pontuais: 1) 10 Kgf: HE 115,94; HI 108,14; CM 64,78; e 2) 15 Kgf: HE 147,25; HI 143,88; CM 177,87. Foi observado que para os carregamentos fisiológicos a HI apresentou os menores valores de tensão e melhor distribuição entre implante e dentes adjacentes; a CM apresentou os maiores valores de tensão, contudo a distribuição entre implante e dentes adjacentes também foi adequada; a HE mostrou a distribuição menos favorável com tensões na crista mesial do implante. Nos carregamentos pontuais a CM apresentou melhor distribuição de tensões ao longo do implante seguido pela HI e HE. Conclui-se que a distribuição de tensões foi influenciada pelo tipo de conexão protética; sendo que as tensões foram melhor distribuídas na carga oclusal fisiológica. O HI apresentou melhor distribuição de tensões para a carga fisiológica e o CM para a carga pontual, evidenciando melhor desempenho das conexões internas / This study aimed to evaluate the peri-implant stress fields generated from 3 different implant- abutment interfaces external hexagon (EH), internal hexagon (IH) and morse taper (MT); supporting single crowns corresponding to the 2nd mandibular pré-molar via photoelastic analysis. 3 photoelastic models with different implant-abutment connections (HE, HI, CM) supporting metal-ceramic single crowns with adjacent teeth (mandibular 1st molar and 2nd pre-molar) were fabricated. The models were submitted to different loads: physiologic occlusion (15, 20, 25Kgf) and punctual (10, 15Kgf) in the implant-supported crown at the mesial fossa region. The images obtained were inserted in the software Fringes® (Laboratório de Projetos Mecânicos, Universidade Federal de Uberlândia, Uberlândia, Brasil). The maximum stresses were determined and observed at 12 selected points, qualitative and quantitative analysis were performed. The results of the stress (KPa) average of peri-implant regions with the 2 different loads and their respective intensities (Kgf) were: Physiologic occlusion: 1) 15 Kgf: HE 107,42; HI 88,81; CM 182,63; 2) 20 Kgf: HE 185,60; HI 123,77; CM 226,44; and 3) 25 Kgf: HE 207,90; HI 176,88; CM 320,65; Punctual loads: 1) 10 Kgf: HE 115,94; HI 108,14; CM 64,78; and 2) 15 Kgf: HE 147,25; HI 143,88; CM 177,87. With the physiological load the IH showed the lowest stress values and a favorable distribution among implant and adjacent teeth; the MT showed the highest stress values, however a favorable distribution with the adjacent teeth; the EH showed stress values in the cervical mesial point of the implant. For the punctual load the MT showed the best stress distribution within the implant, followed by the IH and EH. It was concluded that stress patterns were influenced by the connection design and were more favorable with the physiological occlusion load for all connections. The IH showed better stress distribution with the physiological occlusion load and the MT with the punctual load, showing better performance for internal connections
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Outcomes of mandibular Kennedy class I and II prosthetic rehabilitation

Chamoko, Joanna Yeukai January 2018 (has links)
Magister Scientiae Dentium - MSc(Dent) (Restorative Dentistry) / Loss of teeth has a negative impact on appearance, nutrition, function and diet. Rehabilitation of tooth loss is an important function of oral health care. Rehabilitation with removable prosthesis of mandibular terminal edentulous areas has been associated with more negative outcomes than of tooth-bounded regions.

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