Mestrado em Odontologia (FO)
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Item Efeito do pré-aquecimento e da pós-polimerização nas propriedades mecânicas e grau de conversão de um compósito experimental reforçado com fibra de vidro(Universidade Federal de Goiás, 2016-02-25) Almeida, Letícia Nunes de; Fonseca, Rodrigo Borges; http://buscatextual.cnpq.br/buscatextual/visualizacv.do?metodo=apresentar&id=K4770435A0; Fonseca, Rodrigo Borges; Souza, João Batista de; Menezes, Murilo de SouzaThe pre-heating and post-curing can improve the mechanical properties of composites, even though there be no studies of fiber reinforced composites. The aim of this study was to evaluate the effect of pre-heating and post-curing autoclave and microwave in flexural strength (FS), diametral tensile strength (DTS), knoop microhardness (KHN) and degree of conversion (DC) of a experimental fiber- reinfoced composite. The experimental material was prepared with 30% glass fibers (3 mm), 22.5% of the resin matrix (40/60 Bis-GMA / TEGDMA) and 47.5% barium silicate particles. Six experimental groups were created by the interaction between the factors under study: heating, on two levels (without heating and heating at 60°C) and post-curing in 3 levels (conventional curing without post-curing, autoclave (120°C for 15 minutes) and microwaves (540 W for 5 minutes) The groups were: F - curing at 1500 mW/cm2 for 40 seconds; F + M - curing and post- polymerization in microwave; F + A - curing and post-curing in an autoclave , AQ + F - the composite heating prior to curing, AQ + F + M - heating prior to curing and post-curing in microwave;. AQ + F + A - heating prior to curing and post-curing and autoclave heating was conducted digital oven for 5 minutes at 60°C. Ten samples of the RF dimensions 25 x 2 x 2 mm and DTS in dimensions of 3 x 6 mm were tested in a universal testing machine Instron 5965, 0.5 mm/min. the KHN test was performed on samples of 3 x 6 mm with a load of 50 g for 30 sec, totaling 50 indentations per group. GC was obtained by Spectroscopy Fourier Transform Infrared (FTIR) on 5 samples. Data were analyzed by a factorial 2x3 and general linear model ANOVA and Tukey tests (α = 0.05). Factor analysis showed significant interaction between the factors just for RTD (p = 0.0001); preheating was significant factor for RF (p = 0.0001), RTD (p = 0.020) and KHN (p = 0.0001); post-curing factor for KHN was significant (p = 0.0001). ANOVA and Tukey tests showed statistically significant differences between groups for DTS (p = 0.001: AQ + F ≥ AQ + F + M = F + A = AQ + F + A = F + M ≥ F), FS (p = 0.016: AQ + F + M ≥ AQ + F + A + F = AQ = AQ + A + M ≥ F ≥ F) and KHN (p = 0.0001: AQ + F + M ≥ AQ + A + F = F = F + A + M ≥ F ≥ M + AQ). GC results showed no statistically significant difference. Through the Pearson correlation coefficient was observed significant positive correlation between the GC and RTD (r = 0.473, p = 0.008) and between DTS and FS (r = 0.263, p = 0.042). The pre-heating and post- polymerization were shown to be favorable to promote better mechanical properties of fiber reinforced composite by studied, specific for each property being analyzed.Item Influência da proporção de partículas de reforço nas propriedades mecânicas de um compósito experimental(Universidade Federal de Goiás, 2015-03-24) Andrade, Rodrigo Rocha; Fonseca, Rodrigo Borges; http://lattes.cnpq.br/8629552867290605; Fonseca, Rodrigo Borges; http://lattes.cnpq.br/8629552867290605; Gonçalves, Alberto Magno; Reges, Rogério VieiraPrevious studies show that there is effective interaction between silanized glass fiber and resin matrix formed by methacrylates; However, there is no information on the use of milled glass fiber and the resin incorporated as a filler particle in order to obtain better mechanical properties in composites for the manufacture of intraradiculares pins. The objectives of this study were to evaluate the influence of different types (barium silicate and / or glass fiber powder) and charged particle concentrations in flexural strength, resistance to diametrical and Knoop microhardness traction, an experimental composite composed of 47.5% loading of particles, 30 % glass fiber and resin matrix of 22.5% (BISGMA and TEGDMA (1: 1)); evaluate the morphology of the filler particles and their interaction with the experimental composite in scanning electron microscopy. For producing glass fiber powder, fibers were milled in a mortar grinder / pestle, and then six experimental groups (N = 10) were prepared, varying the ratio of the kind of charged particle: CONTROL - 47.5% barium silicate and 0.0% glass fiber powder; G7.5 - 40.0% barium silicate and 7.5% glass fiber powder; G17.5 - barium silicate 30.0% and 17.5% glass fiber powder; G27.5 - barium silicate 20.0% and 27.5% glass fiber powder; G37.5% - 10.0% barium silicate and 37.5% glass powder vibrates; G47.5% - 0.0% barium silicate and 47.5% glass fiber powder. Cylindrical samples (3 mm x 6 mm) were produced for the diametral tensile strength test, and samples in bar format (25 mm x 2 mm x 2 mm) for flexural and microhardness knoop throws. Resistance tests were performed at 0.5 mm / min on a universal testing machine (Instron 5965). The Knoop microhardness test was made 0.2 KHN (200 g) for 40 seconds at a hardness tester (Shimadzu HMV2). After verification of normality and homogeneity of data distribution with the Kolmogorov-Smirnov test, the data were submitted to ANOVA and Tukey tests (α = 0.05). Statistical analysis demonstrated (p = 0.001): flexural strength: CONTROL - 259.91 ± 26.01a; G7.5 - 212.48 ± 35.91b; G17.5 - 177.63 ± 24.88bc; G27.5 - 166.58 ± 30.84c; G37.5 - 92.08 ± 6.46d; G47.5 - 80.60 ± 17.89d; Diametral tensile strength: CONTROL - 31.05 ± 2.98a; G7.5 - 14.55 ± 3.70b; G27.5 - 12.65 ± 3.34bc; G17.5 - 8.62 ± 3.51cd; G47.5 - 8.04 ± 1.63d; G37.5 - 6.63 ± 2.85d; Knoop microhardness: CONTROL - 75.69 ± 12.19a; G37.5 - 67.62 ± 1.79ab; G27.5 - 65.72 ± 2.01b; G47.5 - 64.06 ± 1.61b; G7.5 - 62.79 ± 2.79b; G17.5 - 59.87 ± 2.33b. The gradual substitution a percentage of the barium silicate glass fiber powder in a glass fiber reinforced composite trial resulted in a decrease in the results of flexural strength, diametral tensile strength and Knoop hardness. Morphologically, glass fiber powder made up of particles with heterogeneous and larger than the particle of barium silicate. The interaction of the glass fiber powder to the resin matrix and fiber reinforcement have not proved effective.Item Influência da composição monomérica e da presença de sal difenil-iodônio nas propriedades mecânicas de resinas experimentais reforçadas com fibras de vidro(Universidade Federal de Goiás, 2017-03-31) Carvalho, Pedro Ivo de; Menezes, Murilo de Souza; http://lattes.cnpq.br/6878077505572368; Fonseca, Rodrigo Borges; http://lattes.cnpq.br/8629552867290605; Fonseca, Rodrigo Borges; Lopes, Lawrence Gonzaga; Lima, Adriano Fonseca deSeveral researches aim to discover a best development of new glass-fiber-reinforced composite resins for the manufacture of intraradicular posts with better mechanical properties has been the aim of several researches lately. The reinforcement of composite resin with glass fibers can improve the mechanical properties, such as flexural strength, fracture resistance and compressive strength. Considering that the resin matrix monomers, the photoinitiator system and the interaction with the glass fibers interfere in the homogenization of the composite and in the degree of polymer conversion, the present work had as Objective: To evaluate the influence of different proportions of the monomers Bis-EMA / Bis-GMA / TEGDMA and photoactivator systems based on DFI and camphorquinone on the mechanical properties of a experimental fiberglass reinforced composite resin. Methodology: Ten groups were created (n = 10) using an experimental resin based on methacrylate, having as study factors: 1. Different matrices according to the proportions of monomers Bis-GMA (BG), TEGDMA (TE) and Bis-EMA (BE): And 2. The photoinitiator system: without DFI (SD) salt or DFI (CD) salt. The samples were prepared for the flexural strength (RF) and diametral tensile strength (RTD) tests. Statistical analysis showed that for RF (Mpa) there was significance in the interaction between the factors under study (p = 0.047). The highest result occurred for Group 10 (267.815 ± 45.05) c, followed by Group 9 (242.440 ± 44.83) bc; Group 8 (241.05 ± 44.83) b Group 3 (236.152 ± 26.42) abc. The lowest result occurred in Group 9 (192.450 ± 12.60) a, followed by Group 7 (202.35 ± 28.36) ab; Group 6 (207,240 ± 30,07) ab; Group 2 (209.530 ± 23.16) ab; Group 5 (216,760 ± 30,14); And Gruop 1 (218,880 ± 41,49). For RTD only the presence of DFI salt showed statistical significance (p = 0.001). The addition of the DFI salt in the composite significantly increased results for flexural strength and diametral tensile strength, while the increase of Bis-EMA was significant for better flexural strength results.Item Estudo das propriedades mecânicas e análise da resistência à fratura de resina de metacrilato reforçada com fibra de vidro e partículas de carga utilizada para confecção de pinos intrarradiculares(Universidade Federal de Goiás, 2014-02-06) Favarão, Isabella Negro; Fonseca, Rodrigo Borges; http://lattes.cnpq.br/8629552867290605; Barata, Terezinha de Jesus Esteves; Gonçalves, Luciano de SouzaThe aim of this study was to characterize the mechanical properties (Flexural strength, Diametral tensile strength, Knoop hardness, Young`s modulus, and Poisson's ratio) of a new experimental composite reinforced with glass fiber, and evaluate the fracture resistance and failure mode of bovine roots post-restored with a new experimental composite produce in direct or indirect (laboratory) mode and compare them with prefabricated fiber glass posts. Experimental composite specimens (22.5% resin, 30% 3mm-short silanized glass fibers, and 47.5% of filler particles) were prepared and tested in a universal testing machine according to the particular methodology of each test, scanning electron microscopy analysis was performed on samples fractured in bending test. Thirty endodontically treated bovine roots were divided into 3 groups (n = 10): PFP: prefabricated fiber glass posts EXP-DIR: posts made of experimental material directly polymerised into the root canal EXP-IND: posts made of experimental material indirectly polymerised. Specimens were subjected to compression load (0.5 mm/min), maximum load recorded in Newton, and fracture ranked as the failure mode. Descriptive analyzes showed averages: 259.91 ± 26.01 MPa (Flexural strength); 31.05 ± 2.97 MPa (Diametral Tensile strength); 135.6 ± 24.8 KHN (Knoop Hardness), 5.6 ± 0.95 GPa (Young`s modulus), 0.34 ± 0.02 (Poisson's ratio). ANOVA and Tukey analyzes showed statistical difference for fracture resistance (p <0.05): PFP (620.72 ± 59.29)A, EXP-IND (506.54 ± 27.07)B, EXP-DIR (157.76 ± 32.34)C. The developed composite showed appropriate mechanical properties and feasibility for production of intracanal posts, however dependent on the method of production, being the indirect method the best.Item Influência do material de reembasamento e do tipo de pino de fibra na distribuição de tensões e resistência à fratura em raízes bovinas(Universidade Federal de Goiás, 2014-02-07) Kasuya, Amanda Vessoni Barbosa; Fonseca, Rodrigo Borges; http://lattes.cnpq.br/8629552867290605; Fonseca, Rodrigo Borges; Batata, Terezinha de Jesus Esteves; Soares, Paulo ViníciusThe aim of this study was to analyze the stress distribution and fracture resistance of personalized posts made of an experimental composite, created by mixing short (3 mm) glass fiber with methacrylate matrix and filler particles and also, to compare personalized post to industrialized and anatomic ones. Four FEA models were created according to the restorative techniques: (FG) teeth restored with industrialized fiber post; (FG+RC) teeth restored with anatomic fiber post reline with resin; (FG+EXP) teeth restored with anatomic fiber post reline with experimental composite; (EXP) teeth restored with personalized post made of experimental composite. σvM and σmax criteria were determinated for stress assessment and specific regions were quantitative analyzed (post/dentin interface, core/dentin interface and post median longitudinal line for σvM, and buccal dentin and palatal dentin for σmax). Forty bovine incisors were divided in the same four groups (N=10). After being post-restored specimens were subjected to compressive-load (Intron 5965) at a 135-degree angle, applied by a 6mm-sphere tip. Failure modes was determined as it follows: (F1) core fracture; (F2) post fracture; (F3) root fracture; (F4) post/core/root set fracture. Stress mesurements and fracture resistance data were submitted to one-way ANOVA, followed by Tukey honestly significant difference test (α=.05). Failure mode were submitted to Kruskal Wallis (α=.05). EXP group showed more homogeneous stress distribution. Significant differences were found among the mean fracture resistance values (p=.000): FG+EXP(669.55±107.71)A; FG(620.72±59.29)A; EXP(506.54±27.07)B; FG+RC(452.75±81.63)B. No differences were found for failure mode (p=.595). The experimental composite significantly increases fracture resistance when used to reline industrialized fiber posts, and irrespenctive of its use, presented a lower σvM stress concentration in FEA models.Item Influência do pH de géis clareadores e do tempo de aplicação em esmalte pré dessensibilizado na topografia e cor dental(Universidade Federal de Goiás, 2016-02-29) Mendes, Gustavo Adolfo Martins; Fonseca, Rodrigo Borges; http://lattes.cnpq.br/8629552867290605; Fonseca, Rodrigo Borges; Barata, Terezinha de Jesus Esteves; Alto, Raphael Vieira MonteTooth bleaching is one of the procedures with the greatest increase in demand, and the number of products and publications in recent years. However, regardless of the technique to be used bleaching, bleaching agents can cause various changes in tooth structure. Some whitening agents have a pH drop over its response action, which can cause changes in the mineral content of the enamel. These changes may be higher when the time of contact between the bleaching agent and the tooth surface is increased. The aim of this study was to investigate the influence of time of application of whitening gel and its effects on tooth structure in pre-desensitized enamel samples with arginine bicarbonate. Eighty enamel blocks (5.5 x 5.5 mm) were obtained from 40 third molar teeth. These were randomly divided into 16 experimental groups (n = 5). Samples were pre-desensitized with arginine bicarbonate (Colgate Pro-Relief) and then bleached as experimental groups, varying the method of application of whitening gels (Opalescence Boost - Ultradent; Total Blanc - DFL) versus time. The pH range of the gel over the application time, the color variation obtained and roughness of the sample surface were evaluated. Results were subjected to statistical analysis with a significance level of 5%, showed similarity between the gels as the bleaching efficiency and roughness standards and longer application times tend to generate higher roughness values. It was concluded that shorter times of application of the whitening gel are more efficient since they cause less damage to enamel and are able to lighten equally and that the use of desensitizing toothpaste Arginine bicarbonate base prior to bleaching does not affect the whitening effect.