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In vivo biological performance of a novel highly bioactive glass-ceramic (Biosilicate (R)): A biomechanical and histomorphometric study in rat tibial defects

GRANITO, Renata N.; RENNO, Ana Claudia; RAVAGNANI, Christian; BOSSINI, Paulo S.; MOCHIUTI, Daniel; JORGETTI, Vanda; DRIUSSO, Patricia; PEITL, Oscar; ZANOTTO, Edgar D.; PARIZOTTO, Nivaldo A.; OISHI, Jorge
Fonte: WILEY-BLACKWELL Publicador: WILEY-BLACKWELL
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.52%
This study aimed to investigate bone responses to a novel bioactive fully crystallized glass-ceramic of the quaternary system P(2)O(5)-Na(2)O-CaO-SiO(2) (Biosilicates (R)). Although a previous study demonstrated positive effects of Biosilicate (R) on in vitro bone-like matrix formation, its in vivo effect was not studied yet. Male Wistar rats (n = 40) with tibial defects were used. Four experimental groups were designed to compare this novel biomaterial with a gold standard bioactive material (Bioglass (R) 45S5), unfilled defects and intact controls. A three-point bending test was performed 20 days after the surgical procedure, as well as the histomorphometric analysis in two regions of interest: cortical bone and medullary canal where the particulate biomaterial was implanted. The biomechanical test revealed a significant increase in the maximum load at failure and stiffness in the Biosilicate group (R) (vs. control defects), whose values were similar to uninjured bones. There were no differences in the cortical bone parameters in groups with bone defects, but a great deal of woven bone was present surrounding Biosilicate (R) and Bioglass (R) 45S5 particulate. Although both bioactive materials supported significant higher bone formation; Biosilicate (R) was superior to Bioglass (R) 45S5 in some histomorphometric parameters (bone volume and number of osteoblasts). Regarding bone resorption...

Dosimetric properties of UV irradiated calcium co-doped borate glass-ceramic

ROJAS, S. S.; YUKIMITU, K.; HERNANDES, Antonio Carlos
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.66%
The thermoluminescence (TL) response of Dy and Li doped 20CaB(4)O(7)-80CaB(2)O(4) (Wt%) glass-ceramic irradiated with ultraviolet (UV) radiation was studied. In order to act as TL activator ions, the Dy and Li ions were included in the matrix during the melting process to increase its TL efficiency. A single crystalline CaB2O4 phase was present in the glass-ceramic as determined by X-ray diffraction (XRD). The glass-ceramic 20CaB(4)O(7)-80CaB(2)O(4):Dy,Li wt% (named 20CBO7:Dy,Li) is a newly prepared TL material. Its thermoluminescent dosimetric characteristics have shown a linear response under UV radiation exposure and a good TL signal reproducibility, thus proving to be a promising material for using as an ultraviolet radiation dosimeter. (C) 2007 Elsevier B.V. All rights reserved.

Propriedades e adesão de cimentos de ionômero de vidro modificados por resina e vitrocerâmicas bioativas; Properties and adhesion of glass ionomer cements modified by resin and bioactive glass-ceramic

Fagundes, Ticiane Cestari
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 17/02/2009 PT
Relevância na Pesquisa
66.79%
As vitrocerâmicas bioativas são materiais sintéticos capazes de aderirem quimicamente aos minerais presentes na estrutura dentária. A união dos cimentos de ionômero de vidro modificados por resina (CIVMRs) à dentina pode ser influenciada por diferentes tipos de tratamentos prévios à restauração. Os objetivos deste estudo foram: avaliar a resistência à compressão, a rugosidade e a adesão à dentina de CIVMRs (Fuji II LC e Vitremer) após a incorporação de partículas de vitrocerâmicas bioativas (Biosilicato®); foi ainda, avaliar a resistência à degradação da adesão à dentina dos CIVMRs, utilizando-se EDTA como pré-tratamento dentinário. Para o teste de resistência à compressão foram confeccionados cilindros sendo que 2, 5 e 10 % em peso de partículas de vitrocerâmica bioativa foram incorporadas aos pós dos CIVMRs, armazenados em água destilada por 24h a 37°C até a realização dos testes. A rugosidade dos cimentos experimentais (2% de vitrocerâmica bioativa) e controles foi avaliada por microscopia de força atômica (MFA) após armazenamento a seco e em 100 % de umidade por 1 mês. Para os testes de microtração, as superfícies das cavidades foram tratadas seguindo-se as instruções dos fabricantes ou utilizando-se EDTA. Os espécimes foram restaurados com os CIVMRs experimentais (2% de vitrocerâmica) e controles. Após as restaurações...

Síntese e caracterização de nanocompósitos vitrocerâmicos transparentes a base de SiO2-ZrO2 dopados com íons Eu3+ e Er3+ via processo sol-gel; Synthesis and characterization of Eu3+ and Er3+ doped SiO2-ZrO2 based transparent glass ceramic nanocomposites via sol-gel process

Remonte, Ádamo Rossano Vicentini
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 27/11/2008 PT
Relevância na Pesquisa
66.47%
A preparação de vitrocerâmicas transparentes a base de SiO2-ZrO2 dopado com íons Eu3+ e Er3+ através da metodologia sol-gel foi o objetivo desta dissertação. São apresentados resultados estruturais e óticos deste sistema, em função de temperatura, tempo e composição (variando-se a concentração de zircônia). Os sóis foram preparados em meio ácido e deixados em repouso até evaporação total do solvente, obtendo-se assim monolitos amorfos, os quais foram submetidos a tratamentos a 900, 1000 e 1100ºC durante 2, 4 e 8 horas visando eliminação de resíduos orgânicos, moléculas de água, grupos hidroxilas e densificação do material. O processo de densificação com os tratamentos leva a formação inicial da fase tetragonal de ZrO2. Foi observado o crescimento de nanopartículas de ZrO2 com dimensão dependente do tempo e temperatura de tratamento térmico, além da composição do nanocompósito. As nanopartículas obtidas apresentam tamanho que variam entre 3,1 a 5,5 nm, observadas por microscopia eletrônica de transmissão. A partir da adição de 20% de óxido de zircônio é possível observar uma mistura de fases entre tetragonal e monoclínica, resultado este evidenciado principalmente por espectroscopia Raman. Neste trabalho...

Osteogênese in vitro sobre vitrocerâmica 100% cristalina e altamente bioativa (Biosilicato®): efeitos do condicionamento de superfície e dos produtos de dissolução iônica; In vitro osteogenesis on a highly bioactive glass ceramic (Biosilicate®): effects of surface conditioning and of its ionic dissolution products

Raucci, Larissa Moreira Spinola de Castro
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 29/05/2009 PT
Relevância na Pesquisa
66.61%
O objetivo deste estudo foi avaliar o efeito do condicionamento de superfície de uma vitrocerâmica 100% cristalina e altamente bioativa (Biosilicato®) e de seus produtos de dissolução iônica sobre diferentes parâmetros do desenvolvimento do fenótipo osteogênico in vitro. Previamente ao plaqueamento de células osteogênicas de calvárias de ratos, discos de Biosilicato® foram condicionados, por 3 dias, em meio de cultura suplementado, com ou sem soro fetal bovino a 10%. Células osteogênicas expostas aos produtos de dissolução iônica do Biosilicato® foram também cultivadas sobre lamínulas de vidro bioinerte. Discos de Biosilicato e lamínulas de vidro foram utilizados como controles. Os resultados mostraram que o tratamento de superfície de Biosilicato® aumenta expressivamente a concentração de silício e cálcio no meio de cultura. Em 1, 3 e 7 dias, foram determinados os maiores valores de viabilidade celular em superfícies de Biosilicato® condicionado, enquanto que entre os grupos de lamínulas de vidro, observou-se menor viabilidade em culturas expostas aos produtos de dissolução iônica do Biosilicato®. Em 3 dias, células sobre todas as superfícies de Biosilicato® apresentavam-se menos espraiadas quando comparadas àquelas sobre lamínulas de vidro; neste período...

Avaliação de um vitrocerâmico elaborado a partir do genérico do biovidro 45S5 em perfurações de tíbias de ratos, e seu comportamento sob influência da radiação laser de baixa intensidade; Evaluation of a glass ceramic produced from the generic of bioglass 45S5 in drilling of tibias of rats, and their behavior under the influence of low-intensity laser radiation

Arruda, Emiliano Rodrigo de Barros
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 26/08/2008 PT
Relevância na Pesquisa
66.8%
O presente trabalho avaliou os efeitos provocados pela laserterapia de baixa intensidade (LTBI) no 'lâmbda' 780 nm, 30 mW de potência e tempo de exposição de 150 segundos, resultando em uma fluência de 112,5 J/'CM POT.2' e energia total de 4,5 J, sobre o comportamento osteocondutor da vitrocerâmica elaborada a partir do genérico do biovidro de composição: 45% 'SI'O IND.2', 24,5% 'NA IND.2'O', 24,5% 'CA'O' e 6% 'P IND.2'O IND.5' em perfurações ósseas em tíbias de ratos. O biovidro foi recozido em cuba de inox acima de sua temperatura de transição vítrea, a 620 graus Celsius por 30 minutos e mantido a 790 graus Celsius por 60 minutos, em seguida foi realizada a espectroscopia Raman para verificar a cristalinidade. Foram realizadas perfurações abaixo da tuberosidade da tíbia direita de 64 machos de ratos da raça Wistar (Rattus norvegicus albinus) na idade adulta. Os mesmos foram divididos aleatoriamente em 4 grupos sendo eles: um controle e três submetidos à procedimento experimental de implante e/ou irradiação laser de baixa intensidade. Em todos os grupos foram utilizados 16 indivíduos. Posteriormente, os animais de cada grupo foram subdivididos em dois subgrupos cada, de acordo com o tempo de vida antes da eutanásia...

Análise da diferenciação osteoblástica in vitro sobre superfícies de materiais vítreos e vitrocerâmicos bioativos; In vitro osteoblastic differentiation on bioactive glass and glassceramic surfaces

Alves, Olivia Cherubin
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 17/08/2012 PT
Relevância na Pesquisa
56.76%
Materiais vítreos e vitrocerâmicos bioativos podem ser usados particulados ou como scaffolds em diferentes tratamentos de defeitos ósseos. Tratamentos térmicos que possibilitam o desenvolvimento de scaffolds a partir de composições de vidros bioativos introduzem fases cristalinas em sua estrutura amorfa com potencial impacto na bioatividade e biocompatibilidade do material. O objetivo do presente estudo foi avaliar, qualitativa e quantitativamente, o desenvolvimento do fenótipo osteogênico de culturas de células osteoblásticas sobre substratos vítreos e vitrocerâmicos bioativos. Células MC3T3-E1 foram cultivadas em condições osteogênicas por períodos de até 21 dias sobre superfícies de Bioglass® 45S5, de duas preparações de vitrocerâmica bioativa e altamente cristalina, Biosilicato® e Biosilicato® para scaffold, e de borosilicato (vidro bioinerte). Foram avaliados, nos períodos de 7, 12 e 21 dias, morfologia celular, formação de matriz mineralizada e expressão de genes relacionados à osteogênese. Os resultados mostraram confluência das culturas sobre as superfícies de vidros e vitrocerâmicas, com progressiva formação de multicamadas celulares. A quantificação de vermelho de Alizarina revelou aumento de mineralização para culturas sobre materiais bioativos...

Vitrocerâmica à base de silicato de lítio para uso como material dentário utilizando casca de arroz como fonte alternativa de silica; Lithium disilicate glass-ceramic used as dental material with silica from rice husk, an alternative source

Santos, Felipe Antunes
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 21/02/2013 PT
Relevância na Pesquisa
66.62%
O presente trabalho sugere a substituição da sílica comercial pela sílica obtida da casca de arroz como fonte alternativa para obtenção do dissilicato de lítio, material que pode ser utilizado em aplicações odontológicas. Para esse fim foram desenvolvidos materiais com estequiometria base de 33,33%mol. Li2O e 66,67%mol. SiO2 com e sem adição de óxidos complementares, visando à obtenção de vitrocerâmicas de maior tenacidade, por meio das duas fontes de sílica, comercial e da casca de arroz. Como caracterizações iniciais, foram realizadas difrações de raios X (DRX) para as misturas iniciais das matérias-primas antes e após a fusão para obtenção dos vidros. Para o caso dos materiais sem adição dos óxidos, a caracterização quanto à sua devitrificação, foi realizada por análise térmica diferencial (ATD), utilizando diferentes taxas de aquecimento e granulometrias, para ambas as fontes de sílica. Valores de temperatura de pico de cristalização (Tp), sem adição dos óxidos, ficaram na faixa de 640°C para os materiais de ambas as fontes de sílica. Também por ATD foi analisado o fenômeno de devitrificação dos materiais com adição dos óxidos. Além disso, para observar a existência de fases intermediárias no sistema...

Dosimetric properties of UV irradiated calcium co-doped borate glass-ceramic

Rojas, S. S.; Yukimitu, K.; Hernandes, A. C.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 653-657
ENG
Relevância na Pesquisa
66.66%
The thermoluminescence (TL) response of Dy and Li doped 20CaB(4)O(7)-80CaB(2)O(4) (Wt%) glass-ceramic irradiated with ultraviolet (UV) radiation was studied. In order to act as TL activator ions, the Dy and Li ions were included in the matrix during the melting process to increase its TL efficiency. A single crystalline CaB2O4 phase was present in the glass-ceramic as determined by X-ray diffraction (XRD). The glass-ceramic 20CaB(4)O(7)-80CaB(2)O(4):Dy,Li wt% (named 20CBO7:Dy,Li) is a newly prepared TL material. Its thermoluminescent dosimetric characteristics have shown a linear response under UV radiation exposure and a good TL signal reproducibility, thus proving to be a promising material for using as an ultraviolet radiation dosimeter. (C) 2007 Elsevier B.V. All rights reserved.

Osteoconductivity of modified fluorcanasite glass-ceramics for bone tissue augmentation and repair

Bandyopadhyay-Ghosh, S.; Faria, P. E. P.; Johnson, A.; Felipucci, D. N. B.; Reaney, I. M.; Salata, L. A.; Brook, I. M.; Hatton, P. V.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 760-768
ENG
Relevância na Pesquisa
56.71%
Modified fluorcanasite glasses were fabricated by either altering the molar ratios of Na 2O and CaO or by adding P 2O 5 to the parent stoichiometric glass compositions. Glasses were converted to glass-ceramics by a controlled two-stage heat treatment process. Rods (2 mm x 4 mm) were produced using the conventional lost-wax casting technique. Osteoconductive 45S5 bioglass was used as a reference material. Biocompatibility and osteoconductivity were investigated by implantation into healing defects (2 mm) in the midshaft of rabbit femora. Tissue response was investigated using conventional histology and scanning electron microscopy. Histological and histomorphometric evaluation of specimens after 12 weeks implantation showed significantly more bone contact with the surface of 45S5 bioglass implants when compared with other test materials. When the bone contact for each material was compared between experimental time points, the Glass-Ceramic 2 (CaO rich) group showed significant difference (p = 0.027) at 4 weeks, but no direct contact at 12 weeks. Histology and backscattered electron photomicrographs showed that modified fluorcanasite glass-ceramic implants had greater osteoconductivity than the parent stoichiometric composition. Of the new materials...

Valorization of sugarcane bagasse ash: Producing glass-ceramic materials

Teixeira, Silvio Rainho; Magalhaes, Renata da Silva; Arenales, Amanda; Souza, Agda Eunice de; Romero, M.; Rincon, J. M.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 15-19
ENG
Relevância na Pesquisa
66.66%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Processo FAPESP: 08/04368-4; Some aluminosilicates, for example mullite and wollastonite, are very important in the ceramic and construction industries. The most significant glass-ceramic for building applications has wollastonite as the main crystal phase. In this work we report on the use of sugarcane bagasse ash (SCBA) to produce glass-ceramics with silicates as the major crystalline phases. The glasses (frits) were prepared by mixing ash, limestone (calcium and magnesium carbonates) and potassium carbonate as the fluxing agent. X-ray fluorescence was used to determine the chemical composition of the glasses and their crystallization was assessed by using thermal analysis (DTA/DSC/TGA) and X-ray diffraction. The results showed that glass-ceramic material can be produced with wollastonite as the major phase, at a temperature lower than 900 degrees C. (C) 2014 Elsevier Ltd. All rights reserved.

Multilayered interface in Ti/macor machinable glass-ceramic joints

Guedes, A.; Pinto, A. M. P.; Vieira, M. F.; Viana, Filomena
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2001 ENG
Relevância na Pesquisa
66.58%
Macor® machinable glass-ceramic and commercially pure (cp.) titanium were joined by active metal brazing, using a 64Ag–34.5Cu–1.5Ti (wt.%) filler alloy. The influence of the brazing temperature and holding stage on the microstructure and hardness profile of the interface, as well as on the shear strength of the joint, were assessed. Brazing was performed in a high vacuum furnace at 850, 890 and 930°C for 10 and 30 min. The reaction between the braze alloy and both materials led to the formation of a multilayered interface. The interfacial microstructure was analysed in a scanning electronic microscope (SEM) and the composition of each reaction layer was investigated by energy dispersive X-ray scans (EDS). The interfacial hardness profile was determined by a series of microhardness tests on each reaction layer. The mechanical strength of the joint was assessed from shear tests conducted at room temperature. Brazing at 850°C with a 10 min holding stage produced stronger joints, with an average shear strength of more than 85% of the glass-ceramic bulk strength.

Preparation and in vitro characterization of scaffolds of poly(L-lactic acid) containing bioactive glass ceramic nanoparticles

Hong, Z.; Reis, R. L.; Mano, J. F.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2008 ENG
Relevância na Pesquisa
66.47%
Porous nanocomposite scaffolds of poly(L-lactic acid) (PLLA) containing different quantities of bioactive glass ceramic (BGC) nanoparticles (SiO2:CaO:P2O5 ! 55:40:5 (mol)) were prepared by a thermally induced phase-separation method. Dioxane was used as the solvent for PLLA. Introduction of less than 20 wt.% of BGC nanoparticles did not remarkably affect the porosity of PLLA foam. However, as the BGC content increased to 30 wt.%, the porosity of the composite was observed to decrease rapidly. The compressive modulus of the scaffolds increased from 5.5 to 8.0 MPa, while the compressive strength increased from 0.28 to 0.35 MPa as the BGC content increased from 0 to 30 wt.%. The in vitro bioactivity and biodegradability of nanocomposites were investigated by incubation in simulated body fluid (SBF) and phosphate-buffered saline, respectively. Scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy and X-ray diffraction were employed to monitor the surface variation of neat PLLA and PLLA/ BGC porous scaffolds during incubation. PLLA/(20 wt.%)BGC composite exhibited the best mineralization property in SBF, while the PLLA/(10 wt.%)BGC composite showed the highest water absorption ability.

Preparation and in vitro characterization of novel bioactive glass ceramic nanoparticles

Hong, Z.; Reis, R. L.; Mano, J. F.
Fonte: John Wiley & Sons Publicador: John Wiley & Sons
Tipo: Artigo de Revista Científica
Publicado em //2009 ENG
Relevância na Pesquisa
66.47%
SiO2-CaO-P2O5 ternary bioactive glass ceramic (BGC) nanoparticles with different compositions were prepared via a three-step sol-gel method. Polyethylene glycol was selected to be used as the surfactant to improve the dispersion of the nanoparticles. The morphology and composition of these BGC nanoparticles were observed by ESEM and EDX. All the BGC particles obtained in this method were about 20 nm in diameter. XRD analysis demonstrated that the different compositions can result in very different crystallinities for the BGC nanoparticles. Bioactivity tests in simulated body fluid solution (SBF), and degradability in phosphate buffer solution (PBS), were performed in vitro. SEM, EDX, and XRD were employed to monitor the surface variation of neat poly(L-lactic acid), PLLA, foam and PLLA/BGC porous scaffolds during incubation. The BGC nanoparticles with lower phosphorous and relative higher silicon content exhibited enhanced mineralization capability in SBF and a higher solubility in PBS medium. Such novel nanoparticles may have potential to be used in different biomedical applications, including tissue engineering or the orthopedic field.

Surface reactivity enhancement of silica-based glass-ceramic scaffolds; Aumento da reactividade superficial de suportes porosos vitroceramicos à base de sílica

Davim, Erika Judith Cardoso Rodrigues
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
66.84%
A paradigm shift is taking place from using transplanting tissue and synthetic implants to a tissue engineering approach that aims to regenerate damaged tissues by combining cells from the body with highly porous scaffold biomaterials, which act as templates, guiding the growth of new tissue. The central focus of this thesis was to produce porous glass and glass-ceramic scaffolds that exhibits a bioactive and biocompatible behaviour with specific surface reactivity in synthetic physiological fluids and cell-scaffold interactions, enhanced by composition and thermal treatments applied. Understanding the sintering behaviour and the interaction between the densification and crystallization processes of glass powders was essential for assessing the ideal sintering conditions for obtaining a glass scaffolds for tissue engineering applications. Our main goal was to carry out a comprehensive study of the bioactive glass sintering, identifying the powder size and sintering variables effect, for future design of sintered glass scaffolds with competent microstructures. The developed scaffolds prepared by the salt sintering method using a 3CaO.P2O5 - SiO2 - MgO glass system, with additions of Na2O with a salt, NaCl, exhibit high porosity, interconnectivity...

Conversion of sandy tailing from banded iron formation exploitation into glass-ceramic materials

Melo,Valéria Alves Rodrigues de; Lameiras,Fernando Soares; Tolentino,Evandro
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2012 EN
Relevância na Pesquisa
66.66%
Glass-ceramic materials made of 40.0 wt. (%) of sandy tailing from banded iron formation exploitation and 60 wt. (%) of slag from steelwork were analyzed. Vitrification was obtained by heating the batch samples up to 1400 °C for 1 hour and quenching the melt on a stainless steel plate. Devitrification was obtained by heat-treating the as-quenched glass samples in isothermal conditions at 750 and 1000 °C for 2 hours. FTIR spectroscopy analysis on the devitrified samples indicates a peak shift towards higher wave number with respect to the as-quenched glass because of the crystallization. XRD analysis revealed the presence of crystalline diopside CaMgSi2O6 as the major phase in the glass samples isothermally heat-treated at 1000 °C. Results also indicated that the devitrification at 1000 °C and an incipient devitrification at 750 °C resulted into harder glass-ceramic materials.

Surface/Interface morphology and bond strength to glass ceramic etched for different periods

Naves, Lucas Z.; Soares, Carlos J.; Moraes, Rafael Ratto de; Gon??alves, Luciano S.; Sinhoreti, M??rio Alexandre C.; Correr Sobrinho, Louren??o
Fonte: University of S??o Paulo Publicador: University of S??o Paulo
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
66.61%
This study evaluated the influence of etching periods on the surface/interface morphology and bond strength to glass ceramic with or without application of an unfilled resin after silane. Ceramic discs were divided into 12 groups, defined by etching time with 10% hydrofluoric acid: G1/G7 ??? etching for 10 seconds, G2/G8 ??? 20 seconds; G3/G9 ??? 40 seconds; G4/G10 ??? 60 seconds; G5/G11 ??? 120 seconds and G6/G12???60 + 60 seconds. All the groups were silanated after etching and G7 ??? G12 received a layer of unfilled resin after silane. Microshear testing using resin cement was performed, with 12 resin cylinders tested per group. The data was submitted to two-way ANOVA and the Student-Newman-Keuls??? test (p<0.05). Evaluation of the etching pattern and bonding interfaces was conducted by SEM. The bond strength means (MPa) were: 19.4 ?? 3.5, 22.3 ?? 5.1, 22.2 ?? 3.2, 17.8 ?? 2.1, 15.3 ?? 3.0 and 14.3 ?? 1.8 for G1???G6 and 17.4 ?? 4.8, 21.3 ?? 2.1, 21.1 ?? 2.3, 24.7 ?? 5.8, 20.4 ?? 2.2 and 18.5 ?? 4.6 for G7???G12. Poor etching was detected after 10 seconds of conditioning; whereas deep channels were extensively observed on surfaces etched for 120 and 60 + 60 seconds. Unfilled voids underlying the ceramiccement interface were detected when only silane was applied. Full completion of the irregularities on G11 was detected using unfilled resin. When only silane was applied...

Hard machining, glaze firing and hydrofluoric acid etching: Do these procedures affect the flexural strength of a leucite glass-ceramic?

Fraga, Sara; Valandro, Luiz F.; Bottino, Marco A.; May, Liliana G.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: E131-E140
ENG
Relevância na Pesquisa
66.61%
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Objective. To evaluate the effects of hard machining, glaze firing and hydrofluoric acid etching on the biaxial flexural strength and roughness of a CAD/CAM leucite glass-ceramic; to investigate if ceramic post-machining surface roughness is influenced by the machining order and by the pair of burs used for it.Methods. A hundred forty four discs were machined by six nominally identical pairs of burs and divided into groups (n = 24): (1) machining-M, (2) machining and glaze firing-MG, (3) machining and hydrofluoric acid etching-MA, (4) machining, glaze firing and hydrofluoric acid etching-MGA, (5) machining followed by polishing, as a control-MP, (6) machining, polishing and hydrofluoric acid etching-MPA. The roughness after each treatment (R-a, and R-z) was measured. The discs were submitted to a piston-on-three ball flexure test (ISO 6872/2008) and strength data analyzed through Weibull statistics (95% CI).Results. M resulted in lower characteristic strength (sigma(0)) (128.2 MPa) than MP (177.2 MPa). The glaze firing reduced sigma(0) (109 MPa), without affecting roughness. Hydrofluoric acid etching increased the roughness without affecting sigma(0) Spearman's coefficient (r(s)) indicated strong and significant correlation between machining order and roughness (r(s)R(a) = -0.66; r(s)R(Z)...

Effect of hydrofluoric acid etching duration on the roughness and flexural strength of a lithium disilicate-based glass ceramic

Zogheib,Lucas Villaça; Bona,Alvaro Della; Kimpara,Estevão Tomomitsu; Mccabe,John F.
Fonte: Fundação Odontológica de Ribeirão Preto Publicador: Fundação Odontológica de Ribeirão Preto
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2011 EN
Relevância na Pesquisa
66.68%
The aim of this study was to examine the effect of different acid etching times on the surface roughness and flexural strength of a lithium disilicate-based glass ceramic. Ceramic bar-shaped specimens (16 mm x 2 mm x 2 mm) were produced from ceramic blocks. All specimens were polished and sonically cleaned in distilled water. Specimens were randomly divided into 5 groups (n=15). Group A (control) no treatment. Groups B-E were etched with 4.9% hydrofluoric acid (HF) for 4 different etching periods: 20 s, 60 s, 90 s and 180 s, respectively. Etched surfaces were observed under scanning electron microscopy. Surface profilometry was used to examine the roughness of the etched ceramic surfaces, and the specimens were loaded to failure using a 3-point bending test to determine the flexural strength. Data were analyzed using one-way ANOVA and Tukey's test (?=0.05). All etching periods produced significantly rougher surfaces than the control group (p<0.05). Roughness values increased with the increase of the etching time. The mean flexural strength values were (MPa): A=417 ± 55; B=367 ± 68; C=363 ± 84; D=329 ± 70; and E=314 ± 62. HF etching significantly reduced the mean flexural strength as the etching time increased (p=0.003). In conclusion...

Development of mica glass-ceramic glazes

Romero, Maximina; Rincón López, Jesús María; Acosta, Anselmo
Fonte: Blackwell Publishing Publicador: Blackwell Publishing
Tipo: Artículo Formato: 1171752 bytes; application/pdf
ENG
Relevância na Pesquisa
66.47%
The effect of iron content on crystallization of a mica glaze as coating for fast firing stoneware substrates has been investi¬gated. Measurements by differential thermal analysis (DTA) combined with X-ray diffraction (XRD) and scanning electron microscopy (SEM) have shown the development of preferential crystal orientation in the mica glass-ceramic glaze. By com¬parison with amorphous and partly crystalline glazes, an enhancement of the mechanical properties of coatings with aligned and interlocked crystals of mica has been observed.; Peer reviewed