Orientador: Rafael Leonardo Xediek Consani / Texto em português e inglês / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-25T06:50:42Z (GMT). No. of bitstreams: 1 Bacchi_Atais_D.pdf: 1480731 bytes, checksum: de48bd5276e26a7e24f1506dd970897a (MD5) Previous issue date: 2014 / Resumo: O objetivo neste estudo foi formular cimentos resinosos a partir de oligômeros tiouretanos, com o propósito de melhorar as propriedades mecânicas do material e minimizar a contração e a tensão de polimerização. Materiais fotopolimerizados e de ativação dupla foram avaliados. Dois oligômeros foram sintetizados ao combinar 1,6-hexanodiol-diisocianato (HDDI) (alifático) com pentaeritritol tetra-3-mercaptopropionato (PETMP) ou 1,3-bis(isocianato-1-metiletil) benzeno (BDI) (aromático) com trimetilol-tris-3-mercaptoproprianato (TMP), na proporção de 1:2 de isocianato e tiol, mantendo grupos tiol pendentes. Inicialmente, 10-30% em peso de ambos os tiouretanos foram adicionados à matriz orgânica formada por BisGMA-UDMA-TEGDMA (nas proporções 50-30-20%, em peso) para o cimento experimental fotopolimerizado. A este, 25% em peso de partículas inorgânicas foram adicionadas. Para o cimento de cura dual, composto pela mesma matriz orgânica e partículas de carga, e para dois materiais comerciais ¿ RelyX Veneer e RelyX Ultimate (3M Espe) - apenas a versão aromática em 10 e 20% em peso foi avaliada. Para todos os materiais, as propriedades mecânicas foram avaliadas através do teste de flexão por três pontos (ISO 4049) para a resistência à flexão (RF), módulo de elasticidade (E) e tenacidade (T). A tenacidade à fratura (KIc) foi avaliada em amostras entalhadas (ASTM Standard E399-90). A tensão de polimerização (TP) foi avaliada usando o aparelho Bioman. Os materiais fotopolimerizados foram avaliados quanto à contração de polimerização (CP) pelo método do disco aderido e a cinética de polimerização (grau de conversão (GC), taxa máxima de polimerização (Rpmax) e vitrificação) avaliadas por infravermelho. A união de uma cerâmica vítrea e um compósito restaurador indireto à dentina foi avaliada com o cimento comercial dual com 0, 10 e 20 % de tiouretano. Os resultados foram submetidos à Análise de Variância e teste de Tukey (?=5%). Quanto ao GC, ocorreu aumento pela utilização da versão alifática nos cimentos experimentais fotoativados; entretanto, a versão aromática não promoveu alteração relevante no GC final dos materiais. Rpmax foi menor nos grupos tiouretanos sendo também significantemente menor para os alifáticos quando comparados aos aromáticos. Apesar de os tiouretanos influenciarem a vitrificação (p=0,035) no cimento experimental, os resultados não foram conclusivos pela análise de Tukey. No cimento comercial foi observado aumento da vitrificação pelo uso do oligômero. Nos cimentos experimentais, RF aumentou com o oligômero aromático e 20% em peso do alifático nos cimentos fotopolimerizados; para E, a versão aromática no cimento com ativação dupla e 10% em peso no material fotopolimerizado causou aumento nos valores. Os materiais comerciais tiveram redução de E com 20% em peso de oligômero, decorrente da redução da proporção de carga inorgânica da matriz. Aumento significante em tenacidade ocorreu nos grupos alifáticos no material fotopolimerizado e para 20% em peso de aromático no cimento dual. K1c aumentou significativamente em ambos os materiais experimentais contendo tiouretano em ambas as concentrações, sendo mais pronunciada em alifáticos na versão fotopolimerizada. Ainda, KIc aumentou com 20% em peso do oligômero em materiais comerciais. A CP reduziu significantemente nos grupos tiouretanos, especialmente para o oligômero alifático no cimento experimental fotopolimerizado. A TP reduziu com os oligômeros de maneira mais acentuada para alifáticos no cimento experimental fotopolimerizado. O uso dos aromáticos em cimentos de ativação dupla também causou redução na TP, e quando com 20% em peso nos materiais comerciais. A modificação do cimento comercial de ativação dupla com 20% em peso do oligômero aromático aumentou a adesão do compósito indireto e da cerâmica vítrea à dentina coronária. Em geral, oligômeros tiouretanos melhoraram as propriedades dos cimentos resinosos avaliados / Abstract: The aim of this study was to formulate resin cements with thio-urethane oligomers to improve mechanical properties and minimize shortcomings related to the volumetric shrinkage and polymerization stress. Light- and dual-cured materials were evaluated. Oligomers were synthesized by combining 1,6-Hexanediol-diissocyante (aliphatic) with pentaerythritol tetra-3-mercaptopropionate (PETMP) or 1,3-bis(1-isocyanato-1-methylethyl)benzene (aromatic) with trimethylol-tris-3-mercaptopropionate (TMP), at 1:2 isocyanate:thiol, leaving pendant thiols. Oligomers were added at 10-30wt% to BisGMA-UDMA-TEGDMA (5:3:2). 25wt% silanated inorganic fillers were added. The dual-cured cement, composed by the same organic matrix and filler particles, and for two commercial cements (RelyX Veneer e RelyX Ultimate; 3M Espe) were only evaluated with the addition of the aromatic version in 10 and 20 wt%. For all materials, the mechanical properties were evaluated by the three-point bending test (ISO 4049) for the flexural strength (FS) elastic modulus (E) and toughness (T). The fracture toughness was evaluated with notched specimens (ASTM Standard E399-90). The polymerization stress (PS) was evaluated in the Bioman. For the light-cured materials, the volumetric shrinkage (VS) was evaluated by the bonded-disc method and the polymerization kinetics ¿ degree of conversion (DC), maximum rate of polymerization (Rpmax) and vitrification ¿ evaluated by near-infrared (NIR). The bonding of a glass ceramic and an indirect composite to dentin were evaluated with the dual-cured commercial cement with 0, 10 and 20 wt% of thio-urethane. Data were analyzed with ANOVA and Tukey¿s test (?=5%). Regarding the DC, an increase was observed in the light-cured materials containing the aliphatic version. The aromatic oligomer did not promote relevant influence the materials. Rpmax was lower for thio-urethane groups being also significantly lower for the aliphatic group when compared to the aromatic. ANOVA has shown the thio-urethane influencing the vitrification (p=0.035) in the experimental cement, but the results were not conclusive by the Tukey¿s test. For the commercial cement, an increase in the vitrification was observed in the thio-urethane-modified group. For experimental cements, FS increased with the use of 10-30 wt% aromatic oligomer and with 20 wt% of aliphatic for light-cured cements. E was only higher for the aromatic version at 10 wt%. The commercial cements presented a reduction in E with 20 wt% of oligomer caused by the reduction in the filler proportion. A significant increase in T occurred in the aliphatic groups for the light-cured group and for 20 wt% of aromatic in the dual-cured cement. KIc significantly increased in both experimental materials formulated with thio-urethane for both concentrations, being more evident for the aliphatic group in the light-cured version. KIc also increased with the aromatic oligomer in commercial materials. The VS was significantly reduced in the thio-urethane groups, mainly for the aliphatic version in the light-cured cement. The PS decreased in the groups formulated with oligomers in the light-cured experimental materials, being also significant for aliphatics. The use of aromatic oligomer also reduced the PS when added to a 20 wt% proportion of organic matrix. The modification of a dual-cured commercial cement with 20wt% of aromatic oligomer led to an increase in the bond strength of an indirect composite and a glass ceramic to the coronal dentin. Thus, it can be concluded that thio-urethane oligomers improved the properties of resin cements / Doutorado / Protese Dental / Doutor em Clínica Odontológica

Magister Chirurgiae Dentium - MChD / The purpose of this study was to investigate the stress produced around the angled distal implants under simulated occlusal loading in the All-on-Fourª concept by means of two-dimensional photoelastic stress models. / South Africa

Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains vii, 47 p. : ill. (some col.) Vita. Includes abstract. Includes bibliographical references (p. 41-46).

No description available.

<p>Both light-cured (LC) and chemically-cured (CC) acrylic resin custom tray materials are used at the Oral Health Centre, Faculty of Dentistry, University of the Western Cape. At present, the CC acrylic is the standard for formal undergraduate teaching and training. The LC material is not part of routine didactic teaching as little evidence-based scientific information is available with regards to its properties and its usage in the clinical environment. Negative effects have caused researchers to focus on alternatives and to research for other materials with more advantageous properties. The objectives of this study was to determine the linear dimensional shrinkage and fracture toughness of light-cured acrylic custom tray materials and compare it to the chemically-cured type. Also to evaluate the acceptance of light-cured acrylic resin custom trays by undergraduate students.</p>

Objective: To determine the long-term prosthodontic maintenance requirements of mandibular unsplinted, two-implant overdentures, using different attachment systems and loading protocols. Materials and Methods: An original total of 106 participants were randomly allocated to one of four different implant systems (Brånemark, Steri-Oss, Straumann and Southern Implant systems). Three different loading strategies were used (2-weeks, 6-weeks and 12-weeks). A total of six different unsplinted attachment systems for mandibular two-implant overdentures were used with the four implant systems. These attachment systems included; the Brånemark gold matrix, Straumann gold matrix, Straumann titanium matrix, Southern Implants plastic matrix, Southern Implants palladium matrix and the Steri-Oss rubber matrix. Each matrix group was allocated to one or more loading strategies and data related to prosthodontic maintenance events was collected prospectively from overdenture insertion (baseline) to year eight, according to predefined categories. Data were analysed using SPSS, and levels of statistical significance were set at P < 0.05. To test for significance between multiple groups, ANOVA was used. Where a statistically significant difference existed, a one way ANOVA with Post Hoc tests was performed. Results: A total of 90 participants from all matrix groups were followed for six-years and loading comparisons could only be made up to this time. The Southern palladium matrix was followed for only six-years therefore it could not be included in the eight year analysis. A total of 69 participants remained in the randomised controlled trial after eight years. Mandibular two-implant overdentures fitted with the Steri-Oss rubber matrix displayed the highest mean number of maintenance events at 32.2 (SD 14.5) followed by the Brånemark matrix group at 28.8 (SD 12.6), the Straumann titanium matrix group at 24.9 (SD 10.7) and the Straumann gold matrix group at 12.8 (SD 8.2), over an eight year period. The Southern plastic matrix group had the lowest average number of maintenance events (8.7 SD 4.2) over the eight-year period and this was significant compared with all other groups (P < 0.05). Over six years, there were no significant differences found between the number of prosthodontic maintenance events and the loading strategy used. On average, the Straumann gold matrix lasted for 3.9 (SD 2.1) years which was significantly longer than all other matrices (P < 0.05) over six years. The Southern palladium (3.1 SD 1.7), Brånemark gold (2.7 SD 1.5) and Southern plastic (2.5 SD 1.4) matrices all lasted significantly longer than the Straumann titanium (1.7 SD 0.8) and the Steri-Oss rubber (1.4 SD 0.7) matrices over six years. Conclusions: Mandibular two-implant overdentures using the Southern Implants plastic cap required significantly less prosthodontic maintenance events compared with all other matrix groups. The Straumann gold matrix required significantly less prosthodontic maintenance compared with the Steri-Oss rubber matrix (P<0.05). The Straumann gold matrix also demonstrated the greatest longevity compared with all other matrices (P<0.05). There was no significant difference in the number of prosthodontic maintenance events of two-implant overdentures when loaded at 2, 6 or 12-weeks after implant placement. The prosthodontic maintenance requirements of unsplinted mandibular two-implant overdentures are dependant upon the attachment system chosen.

Thesis (M.Sc.(Odontology))--University of Pretoria, 2009. / Includes bibliographical references (leaves 75-101).

<p>One of the most critical aspects of successful crown and bridgework is temporary restorations. Failure of temporary restoratins often affects the patient's confidence and mau result in unscheduled appointments for repair. This study compared the the fracture toughness of two materials commonly used to fabricate provisional restorations, namely Coldpac, a polymethyl methacrylate and Protemp 3 Garant, a bis-acryl composite. It also compard the fracture toughness of the two materials when reinforced with stainless steel wire, glass fibers and polythylene fibers.</p>

<p>Both light-cured (LC) and chemically-cured (CC) acrylic resin custom tray materials are used at the Oral Health Centre, Faculty of Dentistry, University of the Western Cape. At present, the CC acrylic is the standard for formal undergraduate teaching and training. The LC material is not part of routine didactic teaching as little evidence-based scientific information is available with regards to its properties and its usage in the clinical environment. Negative effects have caused researchers to focus on alternatives and to research for other materials with more advantageous properties. The objectives of this study was to determine the linear dimensional shrinkage and fracture toughness of light-cured acrylic custom tray materials and compare it to the chemically-cured type. Also to evaluate the acceptance of light-cured acrylic resin custom trays by undergraduate students.</p>

<p>One of the most critical aspects of successful crown and bridgework is temporary restorations. Failure of temporary restoratins often affects the patient's confidence and mau result in unscheduled appointments for repair. This study compared the the fracture toughness of two materials commonly used to fabricate provisional restorations, namely Coldpac, a polymethyl methacrylate and Protemp 3 Garant, a bis-acryl composite. It also compard the fracture toughness of the two materials when reinforced with stainless steel wire, glass fibers and polythylene fibers.</p>