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Avalição 'in vitro' da resistência ao cisalhamento de braquetes colados em diferentes sistemas cerâmicos; In vitro short-term evaluation of shear strength of brackets bonded to different porcelain systems

Bonfante, Luiz Fernando
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 24/01/2007 PT
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37.56%
O tratamento ortodôntico em adultos, nos últimos tempos, tem ganhado popularidade na tentativa de melhorar a estética e a função. No entanto, é uma característica comum nestes pacientes, ter os dentes restaurados com facetas de resina, coroas metalo-cerâmicas e/ou porcelana pura. Neste contexto, o ortodontista se defronta com o desafio de colar braquetes em diferentes sistemas cerâmicos, de capacidade desconhecida de resistir às forças de cisalhamento. Portanto, os objetivos deste trabalho foram: 1) Verificar se a força de cisalhamento em braquetes colados em superfícies de porcelana feldspática e AllCeram é afetada por diferentes tempos de ataque com ácido hidrofluorídrico e 2) Observar se existe uma relação direta entre os valores obtidos da força de cisalhamento e o índice remanescente de adesivo (IRA). Sessenta espécimes de porcelana em formato cilíndrico foram aleatoriamente divididos em 3 grupos de 20 espécimes de acordo com o tempo de ataque do ácido hidrofluorídrico de 1 minuto, 30 segundos e 15 segundos (grupos 1, 2 e 3 respectivamente). Outros sessenta espécimes de porcelana AllCeram, com o mesmo formato e divididos da mesma maneira de acordo com o tempo de ataque ácido (grupos 4, 5 e 6 respectivamente). A colagem dos braquetes na superfície cerâmica incluiu aplicação de silano...

Resistência adesiva ao cisalhamento de reparos em porcelana condicionada com laser; Shear bond strenght of porcelain repairs etched with laser

Pedrazzi, Hamilton
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 26/11/2007 PT
Relevância na Pesquisa
37.56%
O objetivo foi avaliar in vitro a resistência ao cisalhamento de reparos em porcelana condicionada com laser e compará-la aos tradicionais métodos de reparo condicionados com ácido hidrofluorídrico e ácido fosfórico. Neste estudo, foram utilizados dois condicionadores químicos de porcelana (ácido hidrofluorídrico a 10% - Dentsply; ácido fosfórico a 37% - 3M ESPE), um agente silano (Rely X Silano - 3M ESPE), um sistema adesivo (Scotchbond Multi-uso - 3M ESPE), um compósito restaurador (Filtek Z250 - 3M ESPE), uma porcelana odontológica (Ceramco 3 - Dentsply) e um laser de alta potência em regime de femtosegundo (Ti:Safira - Libra- S, Coherent). Sessenta pastilhas em porcelana foram confeccionadas e incluídas e anéis de PVC com resina acrílica quimicamente ativada. As pastilhas de porcelana foram polidas com lixas abrasivas em ordem decrescente de abrasividade para o aplainamento da superfície. Foram formados 6 Grupos (n=10) assim divididos: G1 - condicionamento com laser com potência 760mW; G2 - condicionamento com laser com potência de 760mW e aplicação de ácido fosfórico a 37% por 15s; G3: condicionamento com laser com potência de 900mW; G4 - condicionamento com laser com potência de 900mW e aplicação de ácido fosfórico a 37% por 15s; G5 - aplicação de ácido fosfórico 37% por 15s (grupo controle) e G6 - aplicação de ácido fluorídrico a 10% por dois minutos. Após o condicionamento da porcelana...

Estudo da influência das adições de sílica ativa e copolímero estireno acrílico nas propriedades de argamassas para assentamento de porcelanato; Study of the copolymer styrene acrylic and silica fume adittions influence in the properties of mortars to fix porcelain stoneware tiles

Almeida, Alessandra Etuko Feuzicana de Souza
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 16/09/2005 PT
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Apesar de suas excelentes características técnicas e estéticas, a aplicação de porcelanato em fachadas requer especial atenção devido ser um material diferente das cerâmicas convencionais, além de que as fachadas estão sujeitas a diversos agentes capazes de danificar os revestimentos cerâmicos. O baixo índice de absorção de água do porcelanato é a principal causa da perda ou falta de aderência entre o tardoz e a argamassa colante, pois não permite o mecanismo de aderência mecânica existente nas cerâmicas porosas. O presente trabalho visa o estudo de argamassas com adições de látex base estireno acrílico e sílica ativa para o assentamento de porcelanato em fachadas a fim de evitar o aparecimento de patologias decorrentes da falta de aderência. Foram realizados ensaios normalizados para a avaliação das propriedades das argamassas quanto à fixação do porcelanato, além de procedimentos experimentais para a avaliação da microestrutura tais como análises térmicas, difração de raios-X, porosimetria por intrusão de mercúrio, espectroscopia de infravermelho e microscopia eletrônica de varredura associada à espectrografia por dispersão de energia. Os resultados obtidos mostraram que a adição combinada de polímero e sílica ativa às argamassas resultou em elevadas propriedades mecânicas e alta resistência de aderência...

Evaluation of procera/porcelain interface in metal-free prosthesis

Yasuda, S. H.; Guastaldi, A. C.; Vedovato, E.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 606-611
ENG
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Prosthetic substructures for dental application are veneered by porcelain comprising a structure with different elastic modulus and thermal expansion coefficients layers. This structure may present residual stresses in different layers leading to crack propagation and delamination. Although veneering porcelain remains basically on same strength than standard feldspathic porcelains, new ceramic cores have been developed with higher mechanical properties overcoming metal substructures, improving esthetics and biocompatibility. The interface between the Procera dense sintered alumina core and the manufacturer recommended veneering porcelain (AllCeram-Degussa) were evaluated using SEM in coping shaped specimen simulating the standard dental preparation. There were neither crack presences at the interface nor porcelain delamination.

Investigation of the metal/porcelain interface in LASER-welded Ni-Cr-Mo alloy

Ernesto, Vívian Aparecida Ricardo Teixeira; Guastaldi, Antonio Carlos
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 193-199
ENG
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The interface formed between the metal and the porcelain of laser-welded Ni-Cr-Mo alloy was studied on a metallurgical basis. The characterization was carried out by using optical microscope, electron scan microscopy and X-ray dispersive spectroscopy techniques and mechanical three-point flexion tests, in the laser-welded region, with and without porcelain. The union of the porcelain with the alloy is possible only after the oxidation of the metallic surface and the subsequent application of a bonding agent known as opaque. The porcelain applied to the base metal and weld bead showed different behaviours - after the flexion test, the base metal showed cracks, while that in the weld bead broke away completely. It was noted that the region subjected to laser welding had lower adherence to the porcelain than the base metal region, due to microstructural refinement of the weld bead. These results can be shown by the X-ray dispersive spectroscopy carried out on the regions studied. The flexion tests demonstrated that the Ni-Cr-Mo alloy subject to laser welding had significant alterations in its mechanical properties after application of the porcelain.

Influence of buccal cusp reduction when using porcelain laminate veneers in premolars. A comparative study using 3-D finite element analysis

Archangelo, Carlos Marcelo; Rocha, Eduardo Passos; Anchieta, Rodolfo Bruniera; Martin, Manoel; Freitas, Amilcar Chagas; Ko, Ching-Chang; Cattaneo, Paolo M.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 221-227
ENG
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Objectives: Based on a maxillary premolar restored with laminate veneer and using the 3-D finite element analysis (FEA) and mCT data, the aim of this study was to evaluate the influence of different types of buccal cusp reduction on the stress distribution in the porcelain laminate veneer and in the resin luting cement layer. Methods: Two 3-D FEA models (M) of a maxillary premolar were built from mCT data. The buccal cusp reduction followed two configurations: Mt-buccal cusp completely covered by porcelain laminate veneer; and Mp-buccal cusp partially covered by porcelain laminate veneer. The loading (150 N in 458) was performed on the top of the buccal cusp. The finite element software (Ansys Workbench 10.0) was used to obtain the maximum shear stress (σmax) and maximum principal stress (σmax). Results: The Mp showed reduced the stress (σmax) in porcelain laminate veneer (from-2.3 to 24.5 MPa) in comparison with Mt (from-5.3 to 27.4 MPa). The difference between the peak and lower stress values of σmax in Mp (-6.8 to 26.7 MPa) and Mt (-5.3 to 27.4 MPa) was similar for the resin luting cement layer. The structures not exceeded the ultimate tensile strength or the shear bond strength. Conclusions: Cusp reduction did not affect significant increase in σmax and τmax. The Mt showed better stress distribution (τmax) than Mp. © 2011 Published by Elsevier Ireland on behalf of Japan Prosthodontic Society.

Mechanical and chemical analyses across dental porcelain fused to CP titanium or Ti6Al4V

Souza, Julio C. M.; Henriques, Bruno; Ariza, Edith; Martinelli, Antonio E.; Nascimento, Rubens M.; Silva, Filipe S.; Rocha, Luis A.; Celis, Jean-Pierre
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 76-83
ENG
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); The aim of this study was to evaluate the evolution of mechanical properties and chemical variation across veneering dental porcelain fused to different titanium-based substrates. Test samples were synthesized by fusing dental feldspar-based porcelain onto commercially pure titanium grade II or Ti6Al4V alloy. Samples were cross-sectioned at angles of 10 and 90 degrees to the interface plane. Afterwards, nanoindentation tests and Scanning Electron Microscopy (SEM) imaging coupled to an Energy Dispersive Spectroscopy (EDS) system were carried out across interfaces extending from the metal towards the porcelain area. Elemental diffusion profiles across the porcelain-to-metal interfaces were also obtained by EDS analysis. The mismatch in mechanical properties found in porcelain-to-Ti6Al4V interfaces was lower than that of porcelain-to-CP titanium. Cracking was noticed at low-thickness veneering dental porcelain regions after the nanoindentation tests of samples cross-sectioned at low angles to the interface plane. A wide reaction zone between titanium and porcelain as well as higher incidence of defects was noticed at the porcelain-to-CP titanium interfaces. This study confirmed Ti6Al4V as an improved alternative to CF-titanium as it showed to establish a better interface with the veneering dental porcelain considering the slight chemical interaction and the lower mechanical properties mismatch. The elastic modulus of porcelain-to-Ti6Al4V samples showed to be less sensitive to porcelain thickness variations. (C) 2013 Elsevier B.V. All rights reserved.

Strength of 3Y-TZP and feldspathic porcelain subjected to different cooling methods

Almeida-júnior, Antonio Alves De; Longhini, Diogo; Galvão, Beatriz Regalado; Santos, Claudinei Dos; Adabo, Gelson Luis
Fonte: Faculdade de Odontologia de Piracicaba - UNICAMP Publicador: Faculdade de Odontologia de Piracicaba - UNICAMP
Tipo: Artigo de Revista Científica Formato: 124-128
ENG
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); AIM: To investigate the effect of the cooling rate on flexural strength of monolayer and bilayer porcelain/zirconia (Y-TZP) bars. METHODS: Forty-five specimens were made for each design group: (PM) monolithic specimens of veneer porcelain Vita VM9 (Vita, Germany); (ZM) monolithic specimens of zirconia (ZiHP; ProtMat, Brazil); (PB) bilayer specimens zirconia/porcelain with porcelain on lower surface; and (ZB) bilayer specimens porcelain/zirconia with zirconia on lower surface. Each group was cooled by three different methods after porcelain sintering: slow specimens were cooled inside the turned-off furnace; normal specimens were removed from the furnace and cooled in air at room temperature; and fast specimens were removed from the furnace at 910°C and cooled by compressed air for 10 s. Specimens were polished and flexural strength was measured in water at 37 °C (n=15). Maximum load at fracture was recorded, and equations for simple (monolayer) and composite (bilayer) structures were used to calculate the flexural strength. RESULTS were analyzed using one-way ANOVA (p<0.05) and Tukey test separately for each design. RESULTS: The results of one-way ANOVA were statistically significant only for the PB group. The post-hoc Tukey test showed the highest flexural strength for fast cooling and the lowest for slow cooling; the normal cooling was statistically similar to both. CONCLUSIONS: Cooling methods affected only the flexural strength of bilayer specimens with porcelain on low surface (under tension) when the slow cooling method was used.

Análise microestrutural e das propriedades mecânicas e de durabilidade de argamassas e concretos com isoladores elétricos de porcelana; Microstructural analysis and of mechanical and durability properties of mortars and concretes with porcelain electric insulator

Marco Antonio Campos
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 22/11/2011 PT
Relevância na Pesquisa
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Pesquisas para utilização de materiais reciclados e/ou inservíveis da construção civil em seus insumos, concretos e argamassas, é prática recorrente há seis décadas no mundo. No Brasil este uso vem ganhando destaque a cerca de vinte anos principalmente com os entulhos de construção e da cerâmica vermelha. Há uma lacuna a ser preenchida pela cerâmica branca, em especial pelos isoladores elétricos de porcelana, pois seu passivo nacional anual é de 25.000 toneladas proveniente sobretudo da substituição de peças obsoletas. O objetivo deste trabalho foi comprovar a utilização desta porcelana em concretos e argamassas através de sua incorporação com diferentes graus de moagem, variando de granulometria similar ao cimento até aos agregados, miúdo e graúdo, além do estudo referente a influência da camada de esmalte externa aos isoladores através de ensaios mecânicos, de durabilidade e de imagens por MEV e EDS. Para a adição da cerâmica ao cimento nos teores em massa de 5%, 10%, 25%, 50% e 70%, nas argamassas a melhora nos resultados dos ensaios realizados comprovam sua atividade pozolânica e sua potencialidade de uso. Nos ensaios dos concretos com isoladores de porcelana substituindo o agregado miúdo comum ou ambos os agregados...

Evaluation of a plastic clay from the state of Rio de Janeiro as a component of porcelain tile body

Vieira,C. M. F.; Monteiro,S. N.
Fonte: Rede Latino-Americana de Materiais Publicador: Rede Latino-Americana de Materiais
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2007 EN
Relevância na Pesquisa
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The objective of this work was to evaluate the possibility of using a clay from the city of Silva Jardim, State of Rio de Janeiro, Brazil, in the composition of porcelain tile body. The clay investigated was a plastic kaolinitic type with white color. Initially, a typical porcelain body composed of the mixture of this clay with feldspar, quartz, kaolin and talc was prepared. Specimens were then obtained from this porcelain mixture by uniaxially pressing samples until a dry density of 2.0 g/cm3 was achieved. These specimens were then fired at 1180°C in a laboratory furnace. Physical and mechanical properties related to linear shrinkage, water absorption and flexural rupture strength, determined by Weibull statistical method, were evaluated. Microstructural analysis for the experimental body was performed by scanning electron microscopy, X-ray diffraction and mercury porosimetry. The technological properties of the elaborated composition satisfied the porcelain tile standard specifications. The microstructural analysis displayed small pores as well as a glassy matrix. The presence of quartz, mullite and plagioclase were also detected in the fired porcelain tile. These results indicated that the clay presents satisfactory characteristics to be used in porcelain tile body.

Strength of 3Y-TZP and feldspathic porcelain subjected to different cooling methods

Almeida-Júnior,Antonio Alves de; Longhini,Diogo; Galvão,Beatriz Regalado; Santos,Claudinei dos; Adabo,Gelson Luis
Fonte: Faculdade de Odontologia de Piracicaba - UNICAMP Publicador: Faculdade de Odontologia de Piracicaba - UNICAMP
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2014 EN
Relevância na Pesquisa
37.59%
AIM: To investigate the effect of the cooling rate on flexural strength of monolayer and bilayer porcelain/zirconia (Y-TZP) bars. METHODS: Forty-five specimens were made for each design group: (PM) monolithic specimens of veneer porcelain Vita VM9 (Vita, Germany); (ZM) monolithic specimens of zirconia (ZiHP; ProtMat, Brazil); (PB) bilayer specimens zirconia/porcelain with porcelain on lower surface; and (ZB) bilayer specimens porcelain/zirconia with zirconia on lower surface. Each group was cooled by three different methods after porcelain sintering: slow specimens were cooled inside the turned-off furnace; normal specimens were removed from the furnace and cooled in air at room temperature; and fast specimens were removed from the furnace at 910°C and cooled by compressed air for 10 s. Specimens were polished and flexural strength was measured in water at 37 °C (n=15). Maximum load at fracture was recorded, and equations for simple (monolayer) and composite (bilayer) structures were used to calculate the flexural strength. RESULTS were analyzed using one-way ANOVA (p<0.05) and Tukey test separately for each design. RESULTS: The results of one-way ANOVA were statistically significant only for the PB group. The post-hoc Tukey test showed the highest flexural strength for fast cooling and the lowest for slow cooling; the normal cooling was statistically similar to both. CONCLUSIONS: Cooling methods affected only the flexural strength of bilayer specimens with porcelain on low surface (under tension) when the slow cooling method was used.

All-ceramic and porcelain-fused-to-metal fixed partial dentures: a comparative study by 2D finite element analyses

Motta,Andréa Barreira; Pereira,Luiz Carlos; Cunha,Andréia R.C.C da
Fonte: Faculdade De Odontologia De Bauru - USP Publicador: Faculdade De Odontologia De Bauru - USP
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2007 EN
Relevância na Pesquisa
37.51%
All-ceramic fixed partial dentures (FPDs) have an esthetic approach for oral rehabilitation. However, metal-ceramic FPDs are best indicated in the posterior area where the follow-up studies found a lower failure rate. This 2D finite element study compared the stress distribution on 3-unit all-ceramic and metal-ceramic FPDs and identified the areas of major risk of failure. Three FPD models were designed: (1) metal-ceramic FPD; (2) All-ceramic FPD with the veneering porcelain on the occlusal and cervical surface of the abutment tooth; (3) All-ceramic FPD with the veneering porcelain only on the occlusal surface. A 100 N load was applied in an area of 0.5 mm² on the working cusps, following these simulations: (1) on the abutment teeth and the pontic; (2) only on the abutment teeth; and (3) only on the pontic. Relative to the maximum stress values found for the physiological load, all-ceramic FPD with only occlusal veneering porcelain produced the lowest stress value (220 MPa), followed by all-ceramic FPD with cervical veneering porcelain (322 MPa) and metal-ceramic FPD (387 MPa). The stress distribution of the load applied on the abutments was significantly better compared to the other two load simulations. The highest principal stress values were low and limited in a small area for the three types of models under this load. When the load was applied on the pontic...

Orthodontic bonding to porcelain surfaces: in vitro shear bond strength

Guimarães,Magáli Beck; Lenz,Helen Fernandes; Bueno,Rodrigo Salbego; Blaya,Micéli Beck Guimarães; Hirakata,Luciana Mayumi
Fonte: Pontifícia Universidade Católica do Rio Grande do Sul Publicador: Pontifícia Universidade Católica do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 EN
Relevância na Pesquisa
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PURPOSE: To evaluate in vitro the shear bond strength of orthodontic accessories to porcelain, under different porcelain surface treatment protocols, and the resultant failure pattern after debonding. METHODS: The sample consisted of 80 feldspathic porcelain discs, divided into 4 groups: Group 1 - 37% Phosphoric acid etching; Group 2 - 10% fluorhydric acid; Group 3 - 37% Phosphoric acid and silane application; Group 4 - 10% fluorhydric acid and silane application. The samples were submitted to the shear bond strength test in a universal test machine to record the maximum rupture force. RESULTS: Group 1 showed lower results, and Group 4 presented higher results than the other tested groups.There was no statistical difference between Groups 2 and 3. Groups 1 and 3 presented exclusively adhesive failures between porcelain and resin, whereas Groups 2 and 4 showed cohesive failures in porcelain. CONCLUSION: The use of phosphoric acid followed by silane application was the best protocol for bonding orthodontic accessories to porcelain surfaces, since it was capable of resisting the forces applied during orthodontic treatment without causing irreversible failures in restorations.

Interaction between enamel, porcelain and a gold alloy: an in vitro wear study.

Ha, Uyen Tran Kieu
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2011
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In dental practice, wear of the natural dentition is commonly seen in patients of all ages. It can have a mild effect on teeth, or be severe enough to affect patients’ quality of life. Although different indirect restorative materials such as gold alloy or porcelain have been used for many years to restore excessively worn teeth, the procedures are generally complex and challenging to the dentists as well as costly and time-consuming for the patients. A good restorative material should be aesthetic, durable and not be abrasive to the opposing dentition. Gold has been reported to be “enamel-friendly”, but the colour makes it un-aesthetic. On the contrary, porcelain is aesthetic, biocompatible, durable and has become a popular choice for both clinicians and patients. However, previous studies have shown that some of the porcelain systems can be abrasive to the opposing natural enamel. The use of such abrasive porcelain systems would therefore be harmful to a patient’s dentition in the long term. Four porcelain systems and a gold alloy have been selected for this study: - a veneering porcelain normally used in porcelain bonded to metal restorations (PBM-veneering porcelain). - a leucite-reinforced glass ceramic used for veneering (LR-veneering ceramic). - a leucite-reinforced pressable ceramic (LR-pressable ceramic). - a machinable ceramic. - a type III gold alloy (gold). The aims of the study were to determine the wear rates of the selected porcelains and opposing enamel under controlled conditions which simulated two clinical conditions: - heavy attrition at near neutral pH (pH 6.1). - heavy attrition with gastric regurgitation (pH 1.2). In addition...

Haftfestigkeitsmessungen an keramisch verblendeten Galvanogerüsten; Bond strength of porcelain-veneered electroformed crowns

Walter, Corinna Simone
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
DE_DE
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Keramikverblendete Galvanogoldkronen finden aufgrund positiver klinischer Eigenschaften wie gute Passgenauigkeit, Gewebeverträglichkeit und Ästhetik zunehmende Anerkennung. Jedoch ist der Verbund zwischen Metallgerüst und der Keramikverblendung noch Gegenstand von Untersuchungen, da galvanisches Feingold keine Oxide bildet, welchen nach klassischer Erklärung in der Keramikverblendtechnik von Dentallegierungen das Zustandekommen des Metall-Keramik-Verbundes zugeschrieben wird. Ziel dieser in vitro-Untersuchungen an keramisch verblendeten Galvanogoldkronen war, den Einfluß eines zusätzlich beim Verblenden verwendeten Bonders (HF Goldpaste `Spezial´, C. Hafner) zu untersuchen. Zielgröße war die im zyklischen Dauerlastversuch geprüfte Bruchfestigkeit der Keramikverblendungen. Zur Überkronung eines oberen mittleren Schneidezahnes wurden 54 galvanisch hergestellte Feingoldgerüste (C. Hafner) arbiträr in 2 Gruppen eingeteilt und keramisch verblendet (Vita Response, Vita Zahnfabrik): ohne Bonder (Gruppe O) und mit Bonder (Gruppe B). Je eine Krone diente der Herstellung metallographischer Schnitte zur rasterelektronenmikroskopischen und elementanalytischen Untersuchung der Schichtung. Die fertiggestellten Kronen wurden auf Prüfstümpfe...

Indirect Bonding Method: in vitro Comparison of the Shear Bond Strength between Metallic Orthodontic Brackets and Different Porcelain Surface Preparations

Mai, Stéphanie H.
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
EN
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Introduction : La force d’adhésion à l'interface métal-céramique avec les résines auto-polymérisantes destinées au collage indirect des boîtiers orthodontiques n'a pas été évaluée à ce jour et un protocole clinique basé sur la littérature scientifique est inexistant. Objectifs : 1) Comparer la force de cisaillement maximale entre des boîtiers métalliques et des surfaces en porcelaine préparées selon différentes méthodes; 2) Suggérer un protocole clinique efficace et prévisible. Matériel et méthodes : Quatre-vingt-dix disques en leucite (6 groupes; n = 15/groupe) ont été préparés selon 6 combinaisons de traitements de surface : mécaniques (+ / - fraisage pour créer les rugosités) et chimiques (acide fluorhydrique, apprêt, silane). Des bases en résine composite Transbond XT (3M Unitek, Monrovia, California) faites sur mesure ont été collées avec le système de résine adhésive auto-polymérisante Sondhi A + B Rapid Set (3M Unitek, Monrovia, California). Les échantillons ont été préservés (H2O/24hrs), thermocyclés (500 cycles) et testés en cisaillement (Instron, Norwood, Massachusetts). Des mesures d’Index d’adhésif résiduel (IAR) ont été compilées. Des tests ANOVAs ont été réalisés sur les rangs étant donné que les données suivaient une distribution anormale et ont été ajustés selon Tukey. Un Kruskall-Wallis...

Bonding brackets to porcelain: in vitro study

Sant'Anna,Eduardo Franzotti; Monnerat,Maria Evangelina; Chevitarese,Orlando; Stuani,Maria Bernadete Sasso
Fonte: Fundação Odontológica de Ribeirão Preto Publicador: Fundação Odontológica de Ribeirão Preto
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2002 EN
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The aim of this research was to verify, in vitro, the effect of various porcelain surface treatments on the shear strength of orthodontic brackets bonded to porcelain and the mode of fracture after debonding. Eighty-eight samples of metallic supported feldspathic porcelain were randomly divided into four groups according to their surface preparation as follows: the porcelain was maintained intact (GI), roughened with a diamond bur (GII), etched with 10% hydrofluoric acid (GIII), or sandblasted with aluminum oxide (GIV). The specimens were treated with silane (Scothprime) and brackets were bonded with Concise. Each sample was subjected to a shear load at a crosshead speed of 1 mm/min and a recording was made at the point of failure. Bond strengths, adequate to withstand the application of orthodontic forces, were achieved in all groups. The Kruskal-Wallis statistical test showed no significant differences in bond strength between the groups (p>0.05). However, many more porcelain fractures occurred on deglazed porcelain. This study indicates that with the appropriate material selection, the silane/composite procedure alone may be adequate for bonding.

Effect of firing temperature on sintering of porcelain stoneware tiles; Efecto de la temperatura de cocción en la sinterización de baldosas de gres porcelánico

Martín-Márquez, Jorge; Rincón López, Jesús María; Romero, Maximina
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 595598 bytes; application/pdf
ENG
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Porcelain stoneware tile is a non-equilibrium porcelain material produced by a fast firing process of kaolinitic clay, quartz and feldspar mixtures. This building material, generally used in pavements and also as wall covering and ventilated façades, is endowed with high technological properties such as low water absorption, high bending strength and abrasion resistance and excellent chemical and frost resistance. These properties cause that porcelain stoneware tile was actually the material with the highest increase in production and sales over all other ceramic building material. Nevertheless, there is a scarcity of high quality research focused on the effect of mullite growth on technological properties of porcelain stoneware tile and on the effect of different fluxing agents on both mullite growth and evolution of physical and technological properties during firing. In this paper, the behaviour of a potassic porcelain stoneware body during the firing process is investigated. A porcelain stoneware composition was prepared by mixing 50% kaolinitic clay, 40% feldspar and 10% quartz. The samples were sintered following a fast firing process. The sintering behaviour of the fired samples was evaluated by linear shrinkage, water absorption and porosity measurements. Both green powder and fired samples were characterized by means of differential thermal analysis (DTA)...

All-ceramic and porcelain-fused-to-metal fixed partial dentures: a comparative study by 2D finite element analyses

Motta, Andréa Barreira; Pereira, Luiz Carlos; Cunha, Andréia R.C.C da
Fonte: Universidade de São Paulo. Faculdade de Odontologia de Bauru Publicador: Universidade de São Paulo. Faculdade de Odontologia de Bauru
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; Formato: application/pdf
Publicado em 01/10/2007 ENG
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All-ceramic fixed partial dentures (FPDs) have an esthetic approach for oral rehabilitation. However, metal-ceramic FPDs are best indicated in the posterior area where the follow-up studies found a lower failure rate. This 2D finite element study compared the stress distribution on 3-unit all-ceramic and metal-ceramic FPDs and identified the areas of major risk of failure. Three FPD models were designed: (1) metal-ceramic FPD; (2) All-ceramic FPD with the veneering porcelain on the occlusal and cervical surface of the abutment tooth; (3) All-ceramic FPD with the veneering porcelain only on the occlusal surface. A 100 N load was applied in an area of 0.5 mm² on the working cusps, following these simulations: (1) on the abutment teeth and the pontic; (2) only on the abutment teeth; and (3) only on the pontic. Relative to the maximum stress values found for the physiological load, all-ceramic FPD with only occlusal veneering porcelain produced the lowest stress value (220 MPa), followed by all-ceramic FPD with cervical veneering porcelain (322 MPa) and metal-ceramic FPD (387 MPa). The stress distribution of the load applied on the abutments was significantly better compared to the other two load simulations. The highest principal stress values were low and limited in a small area for the three types of models under this load. When the load was applied on the pontic...

Strength of 3Y-TZP and feldspathic porcelain subjected to different cooling methods

Almeida-Júnior, Antonio Alves de; Longhini, Diogo; Galvão, Beatriz Regalado; Santos, Claudinei dos; Adabo, Gelson Luis
Fonte: UNICAMP/FOP Publicador: UNICAMP/FOP
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ;
Publicado em 07/10/2015 POR
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Aim: To investigate the effect of the cooling rate on flexural strength of monolayer and bilayer porcelain/zirconia (Y-TZP) bars. Methods: Forty-five specimens were made for each design group: (PM) monolithic specimens of veneer porcelain Vita VM9 (Vita, Germany); (ZM) monolithic specimens of zirconia (ZiHP; ProtMat, Brazil); (PB) bilayer specimens zirconia/porcelain with porcelain on lower surface; and (ZB) bilayer specimens porcelain/zirconia with zirconia on lower surface. Each group was cooled by three different methods after porcelain sintering: slow – specimens were cooled inside the turned-off furnace; normal – specimens were removed from the furnace and cooled in air at room temperature; and fast – specimens were removed from the furnace at 910°C and cooled by compressed air for 10 s. Specimens were polished and flexural strength was measured in water at 37 °C (n=15). Maximum load at fracture was recorded, and equations for simple (monolayer) and composite (bilayer) structures were used to calculate the flexural strength. Results were analyzed using one-way ANOVA (p<0.05) and Tukey test separately for each design. Results: The results of one-way ANOVA were statistically significant only for the PB group. The post-hoc Tukey test showed the highest flexural strength for fast cooling and the lowest for slow cooling; the normal cooling was statistically similar to both. Conclusions: Cooling methods affected only the flexural strength of bilayer specimens with porcelain on low surface (under tension) when the slow cooling method was used.