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Mechanical properties of a new zinc-reinforced glass ionomer restorative materialAl-Angari, Sarah Sultan January 2012 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Objective: Zinc-reinforced glass ionomer restorative material (ZRGIC) has been proposed as an improved restorative material. The study compared the mechanical properties of a ZRGIC restorative material (ChemFil Rock, (Dentsply)), with three commercially available glass ionomers (GICs); Fuji IX GP Extra (GC America), Ketac Molar (3M ESPE) and EQUIA Fil (GC America). A resin composite, Premise (Kerr), was included as a control group except for fracture toughness. Methods: Fracture toughness (KIC) testing was done according to ISO 13586, using single edge notched-beam specimens (n=10), loaded until failure in a three-point bending test device. Specimens (n=9) for the hardness, roughness and abrasive wear testing were made by mixing and inserting the restorative materials into individual stainless steel molds followed by flattening and polishing. Knoop microhardness (KHN) was performed (25 g, 30 s),on pre-determined areas of the polished surfaces. For toothbrushing wear resistance and roughness, specimens were brushed in an automated brushing machine (200 g) with a suspension of dentifrice and water (1:1, w/v) for 20,000 strokes. Specimen surfaces were scanned in an optical profilometer before and after brushing to obtain surface roughness (Ra) and mean height (surface) loss using image subtraction and dedicated software. Data were analyzed using Wilcoxon Rank Sum tests (α=0.05). Results: ChemFil Rock had the highest change in surface roughness (Ra)(0.79±0.14; p<0.001) and the lowest microhardness (KHN) values (52.39±2.67; p<0.05) among all GICs. Its wear resistance was comparable to other GICs (p>0.05). ChemFil Rock had lower fracture toughness (0.99±0.07, KIC) compared to Equia Fil (p<0.01) and higher compared to the other GICs (p<0.01). Conclusion: The new ZRGIC restorative material showed intermediate fracture toughness, high change in surface roughness, and low microhardness compared to three other commercial GICs. All materials were supplied by respective manufacturers.
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Polyoxymethylene as Material for Removable Partial Dentures—A Literature Review and Illustrating Case ReportSchierz, Oliver, Schmohl, Leonie, Hahnel, Sebastian, Rauch, Angelika 04 May 2023 (has links)
Compared to thermoplastic manufacturing techniques, computer-aided design (CAD) and computer-aided manufacturing (CAM) technologies make it easier to process modern restorative and prosthetic materials with improved material properties. In dentistry, tooth-colored alternatives to metal-based frameworks for application in removable dental prostheses (RDP) emerged. With regard to this aspect, the current article provides an overview of the specific material properties of polyoxymethylene (POM). Furthermore, it reviews scientific literature indexed in PubMed and Web of Science that focuses on RDPs fabricated from POM within the last 10 years. Finally, a prosthetic rehabilitation of a patient with a RDP fabricated from POM is illustrated and observations during a follow-up over 10 months are described. Scientific data and clinical observations indicate that polyoxymethylene is a promising material that bridges gaps in dental therapeutic options. While survival time may be limited due to wear, POM might be a favorable option for application in semi-permanent restorations.
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Desgaste abrasivo de uma resina composta, através de três diferentes métodos (disco retificado, escovação e nanodurômetro) / Abrasive wear of a composite resin, using three different methods (ground disc, toothbrushing and nanodurometer)Freitas, Márcia Furtado Antunes de 16 September 2011 (has links)
Neste estudo, foi avaliada a resistência ao desgaste abrasivo de uma resina composta, através de três diferentes métodos: do disco retificado, por escovação e do nanodurômetro. Nos dois primeiros métodos, foram utilizados 20 espécimes da resina Filtek Z250 (10 da cor Incisal e 10 da cor C4, ambos fotopolimerizados por 30 segundos cada) e 10 de polimetilmetacrilato (PMMA), atuando estes últimos como padrão de referência. Para os ensaios com o nanodurômetro, foi utilizado apenas um espécime de cada cor, assim como um único de PMMA, em cujas superfícies planas foram efetuadas sete medições, o que foi considerado equivalente a sete espécimes. No método do disco retificado, cada espécime de resina composta era confeccionado diretamente numa cavidade semicircular, localizada na periferia de um disco-suporte; os espécimes de PMMA consistiam em discos constituídos exclusivamente por este material; o desgaste de cada espécime era promovido por um disco de porcelana e seu conseqüente deslocamento era detectado por um palpador; assim, a taxa de desgaste era estabelecida, expressa em milímetros cúbicos por newton por segundo (mm3/N.s). No método de escovação, cada espécime cilíndrico ficava preso numa placa metálica, a qual era fixada no interior da máquina de escovação; sua perda de massa (em miligramas) era verificada através de uma balança analítica. No método do nanodurômetro, existiu apenas um espécime ci líndrico para cada condição, em cuja face plana superior eram feitos sete sulcos (equivalentes a sete espécimes); o coeficiente de atrito permitia estabelecer a respectiva resistência ao desgaste. Para cada método utilizado, os dados foram tratados estatisticamente, através de análise de variância (ANOVA) e de teste de Tukey. Pôde-se concluir que, através do disco retificado, a taxa de desgaste (em mm3/N.s) dos materiais foi: Incisal (0,6807) > C4 (0,5012) > PMMA (0,1439); que, através da escovação, a taxa de desgaste (em mg) foi de 5,40 para Incisal, de 9,35 para C4 e de 5,88 para PMMA, sem diferença significante apenas entre Incisal e PMMA, os mais resistentes; e que, através do nanodurômtero, a resistência ao desgaste abrasivo (expressa pelo coeficiente de atrito) foi de 0,207 para Incisal, de 0,214 para C4 e de 0,281 para PMMA, sem diferença significante agora apenas entre Incisal e C4, os menos resistentes. / Abrasive wear of a composite resin, using three different methods (ground disc, toothbrushing and nanodurometer). The aim at this study was to evaluate the resistance to abrasive wear of a composite resin, using three different methods: ground disc, toothbrushing and nanodurometer. At the first two methods were employed 20 specimens of Filtek Z250 composite resin (10 of Incisal and 10 of C4, both the colors cured for 30 seconds each one) and 10 of polymethylmethacrylate (PMMA), the latter acting as a reference standard. For the tests with the nanodurometer it was used only one specimen of each color, as well as just one of PMMA, in whose flat surfaces seven measurements were made, what was considered equivalent to seven specimens. At the ground disc method, each composite resin specimen was directly made on a semicircular cavity located on the periphery of a supporting disc; PMMA specimens consisted of discs made up exclusively with this material; the wear of each specimen was promoted by a ceramic disc and its consequent displacement was detected by a sensor; thus, the wear rate was established, expressed in cubic millimeters per newton per second (mm3/N.s). At the toothbrushing method, each cylindrical specimen was trapped in a metal plate, which was fixed inside the machine brushing; its weight loss (in milligrams) was verified by an analytical balance. At the nanodurometer method, there was only one cylindrical specimen for each condition, in whose flat upper face seven grooves were made (what was equivalent to seven specimens); the coefficient of friction was used to establish its wear resistance. For each method, data were statistically analyzed by ANOVA and Tukey\'s test. It could be concluded that, by ground disc method, materials wear rate (in mm3/N.s) was Incisal (0.6807) > C4 (0.5012) > PMMA (0.1439); by brushing method, materials wear rate (in mg) was 5.40 for Incisal, 9.35 for C4 and 5.88 for PMMA, without significant difference only between Incisal and PMMA (the toughest); by nanodurometer method, abrasive wear resistance (expressed by the coefficient of friction) was 0.207 for Incisal, 0.214 for C4 and 0.281 for PMMA, now without significant difference just between Incisal and C4, the least resistant.
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Aplicação de ondas de ultra-som sobre cimentos de ionômero de vidro : rugosidade superficial e perda de massa após ensaio de escovação /Coldebella, Cármen Regina. January 2007 (has links)
Orientador: Ângela Cristina Cilense Zuanon / Banca: José Luiz Guimarães Figueiredo / Banca: Lourdes Aparecida Martins dos Santos-Pinto / Resumo: Este trabalho teve como objetivo determinar a influência da excitação ultra-sônica aplicada em dois cimentos de ionômero de vidro nos momentos inicias de sua reação de presa, avaliando a rugosidade superficial e a perda de massa após ensaio de escovação. Os materiais foram o Fuji IX GP (GC Corporation) e Ketac Molar Easymix (3M ESPE), manipulados de acordo com as instruções dos fabricantes e inseridos em matriz confeccionada com dente bovino. Foram confeccionados 16 espécimes de cada material, dos quais a metade recebeu excitação com ondas de ultra-som (PROFI III BIOS - Dabi Atlante) por um período de 30 segundos. Todos os corpos foram pesados diariamente, em balança analítica (Sartoruis), até a estabilização de sua massa, a qual foi alcançada após 20 dias da manipulação. Logo após foi realizada a leitura da rugosidade inicial (rugosímetro Surfcorder SE 1700 - Japão). Em seguida os mesmos foram submetidos ao ensaio de escovação, totalizando 30.000 ciclos. Nova leitura de rugosidade superficial e seqüência de pesagem foram realizadas. Para a análise estatística foram utilizados os testes de Análise de Variância (MANOVA) e t-Student onde a diferença estatística foi determinada por p= 0,05. Observou-se diferença estatística significante na rugosidade superficial antes e após o ensaio de escovação (p= 0,00). Porém não houve diferença estatística na rugosidade quando considerada a aplicação de ondas de ultra-som (p= 0,06). A média de rugosidade após ensaio de escovação para o Fuji IX GP foi de 0,767æm e 0,643æm com e sem a aplicação de ondas de ultra-som respectivamente e para o Ketac Molar Easymix esses valores foram de 0,759æm e 0,757æm para as mesmas condições experimentais. Na interação material, excitação ultra-sônica e ensaio de escovação foi observada diferença... Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this work was to determine the influence of ultrasonic excitation in two glass ionomer cements (GICs) evaluating the superficial roughness and mass loss after toothbrushing test. The GICs tested were Fuji IX GP (GC Corporation) and Ketac Molar Easymix (3M ESPE). The cements were manipulated according to the manufacturesþ instructions and inserted in a bovine tooth matrix. For each material 16 specimens were made. Eight specimens of them were excited with ultrasonic waves (PROFI III BIOS - Dabi Atlante) for 30s. All specimens were weighed daily in an analytical balance (Sartoruis) until their mass stabilization which was reached after twenty days. Next, the initial superficial roughness reading was performed (Surfcorder SE 1700 - Japan). After that, toothbrushing test was performed, and 30.000 cycles were applied. Soon after, a new superficial roughness reading and a sequence of weighing were performed. The statistical analysis was made through MANOVA test and t-Student where p= 0.05 determined a significant statistical difference. A difference on the superficial roughness was observed before and after toothbrushing (p=0.00). However, there was no statistical difference when the ultrasonic waves were used (p=0.06). After toothbrushing test Fuji IX GP roughness average was 0.767æm and 0.643æm with and without the use of ultrasound waves respectively while Ketac Molar Easymix showed 0.759æm and 0.757æm in the same experimental conditions. In the interaction: material, ultrasonic excitation, and toothbrushing test, a significant statistical difference was observed (p=0.004) which was due to the toothbrushing test and not to the use of ultrasonic waves. The mean of weigh loss was 0.45mg for Fuji IX GP with ultrasound excitation, and 0.61mg without this procedure; Ketac Molar Easymix showed 0.27mg and 0.16mg respectively. However, there was no statistica... (Complete abstract, click electronic access below) / Mestre
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Degradação de materiais restauradores resinosos e do esmalte deciduo e permanente em soluções simuladoras da dieta / Degradation of resin-based restorative materials and deciduous and permanent enamel in food-simulating mediaCorrer-Nolasco, Gisele Maria 22 February 2007 (has links)
Orientador: Regina Maria Puppin Rontani / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-08T10:33:11Z (GMT). No. of bitstreams: 1
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Previous issue date: 2007 / Resumo: A cavidade bucal é considerada um ambiente agressivo onde a estrutura dentária e os materiais restauradores estão constantemente sujeitos a desafios térmicos, mecânicos e quÃmicos. A associação destes fatores está diretamente relacionada à longevidade/estabilidade das restaurações, bem como à preservação da estrutura dentária. A exposição da estrutura dentária e dos materiais restauradores resinosos aos agentes da dieta pode causar erosão dental, amolecimento e aumento da rugosidade de restaurações resinosas, deixando-as mais susceptÃveis ao desgaste. Dessa forma, os objetivos desta tese fundamentada em três capÃtulos foram: (1) avaliar o efeito do armazenamento em longo prazo em diferentes soluções simuladoras da dieta na rugosidade superficial de materiais restauradores resinosos; (2) avaliar o efeito da associação dos desafios erosivo e abrasivo no desgaste do esmalte decÃduo e permanente; (3) avaliar o efeito da associação dos desafios corrosivo e abrasivo no desgaste de materiais restauradores resinosos. No capÃtulo 1, sessenta amostras de diferentes materiais restauradores (Filtek Z250, Esthet X, Filtek Flow, Dyract AP e Vitremer) foram armazenadas em 5 lÃquidos simuladores da dieta (água destilada, ácido lático, ácido cÃtrico, refrigerante a base de cola (Coca-Cola) e álcool) por até 6 meses. A rugosidade superficial das amostras foi mensurada após o polimento (baseline), 1 semana, 1 mês, 3 meses e 6 meses de armazenamento. Houve aumento significativo na rugosidade superficial apenas para Esthet X armazenado em Coca-Cola e em ácido cÃtrico após 1 e 3 meses, respectivamente; e para Dyract AP armazenado em água destilada após 6 meses. No capÃtulo 2, foram obtidas amostras planas de esmalte decÃduo e permanente (n=10), as quais foram submetidas ao desgaste (100.000 ciclos a 1,9 Hz) em meio neutro (água deionizada) e meio ácido (ácido cÃtrico). Antes e após o desgaste, as amostras foram analisadas em perfilÃ'metro (MTS 3D Profiler). A alteração do volume e a profundidade máxima do desgaste foram quantificadas utilizando o software Ansur 3D. O esmalte decÃduo apresentou maior desgaste que o esmalte permanente, independentemente do meio. O meio ácido proporcionou maior desgaste do que o meio neutro (p<0,05). Diferença significativa entre meio neutro e ácido foi observada apenas para o esmalte decÃduo. No capÃtulo 3, dez amostras de cada material [Filtek Supreme (S), Point 4 (P), Dyract AP (D) e Fuji II LC (F)] foram confeccionadas e submetidas ao desgaste (100.000 ciclos a 1,9 Hz) em meio neutro (água) e meio ácido (ácido cÃtrico). Antes e após o desgaste, as amostras foram analisadas em perfilÃ'metro (MTS 3D Profiler). A alteração do volume e a profundidade máxima do desgaste foram quantificadas utilizando o software Ansur 3D. Diferença significativa no desgaste dos materiais foi observada (S=P<D<F), independentemente do meio. O meio ácido gerou maior desgaste nos materiais comparado ao meio neutro (p<0,05). Não houve diferença significativa entre o meio neutro e meio ácido para todos os materiais quando analisados individualmente. Concluindo, a degradação quÃmica dos materiais restauradores resinosos é material e solução dependente. O desafio ácido aumenta a susceptibilidade ao desgaste dos materiais restauradores resinosos e do esmalte dental, especialmente esmalte decÃduo / Abstract: The oral cavity can be considered a hostil environment. The dental structure and the restorative materials are constantly subjected to thermal, mechanical and chemical stresses. The interplay of these factors is directly related with the longevity/stability of the restorative treatment, and also with the dental structure preservation. The effect of diet constituents on dental structure and restorative materials can be dental erosion, softening and roughening of resin-based restorations. These phenomena increase the susceptibility of tooth and material wear. This way, the objectives of this work are: (1) to evaluate the effect of long-term storage in different food-simulating media on surface roughness of resin-based materials; (2) to evaluate the effect of the association of erosive and abrasive challenges on deciduous and permanent wear; (3) to evaluate the effect of the association of corrosive and abrasive challenges on resin-based materials wear. In the first chapter, sixty specimens of different material categories (Filtek Z250, Esthet X, Filtek Flow, Dyract AP, and Vitremer) were stored in five food-simulating solutions (distilled water, lactic acid, citric acid, carbonated soft drink (Coca-Cola), and ethanol) for 6 months. The surface roughness was measured after polishing (baseline), 1 week, 1, 3, and 6 months of storage. Significant difference was observed for Esthet X specimens stored in Coca-Cola and in citric acid after 1 and 3 months, respectively; and for Dyract AP specimens stored in distilled water after 6 months. In the second chapter, deciduous and permanent flat enamel specimens (n=10) were obtained. The specimens were subjected to the wear test (100,000 cycles at 1.9 Hz) in neutral (water) or acidic (citric acid) media. Specimens were profiled before and after the wear test using the MTS 3D Profiler. Volume loss and maximum depth were quantified by the Ansur 3D software. Deciduous enamel showed more wear than permanent enamel, regardless the media. The acidic media produced more wear than the neutral media (p<0.05). Significant difference was observed between neutral and acidic conditions only for deciduous enamel. In the third chapter, ten specimens were produced from each material [Filtek Supreme (S), Point 4 (P), Dyract AP (D), and Fuji II LC (F)]. The specimens were submitted to the wear test (100,000 cycles at 1.9 Hz) in neutral (water) and acidic (citric acid) media. Specimens were profiled before and after the wear test using the MTS 3D Profiler. Volume loss and maximum depth were quantified by the Ansur 3D software. Significant differences were observed for the material wear (S=P<D<F), regardless the media condition. Acidic media produced more wear than neutral media (p<0,05). There were no significant differences between neutral and acidic condition for all materials, when individually analyzed. Concluding, the chemical degradation of resin-based materials is material and solution dependent. The acidic media produced more material and tooth wear, especially for deciduous enamel / Doutorado / Materiais Dentarios / Doutor em Materiais Dentários
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Desgaste abrasivo de uma resina composta, através de três diferentes métodos (disco retificado, escovação e nanodurômetro) / Abrasive wear of a composite resin, using three different methods (ground disc, toothbrushing and nanodurometer)Márcia Furtado Antunes de Freitas 16 September 2011 (has links)
Neste estudo, foi avaliada a resistência ao desgaste abrasivo de uma resina composta, através de três diferentes métodos: do disco retificado, por escovação e do nanodurômetro. Nos dois primeiros métodos, foram utilizados 20 espécimes da resina Filtek Z250 (10 da cor Incisal e 10 da cor C4, ambos fotopolimerizados por 30 segundos cada) e 10 de polimetilmetacrilato (PMMA), atuando estes últimos como padrão de referência. Para os ensaios com o nanodurômetro, foi utilizado apenas um espécime de cada cor, assim como um único de PMMA, em cujas superfícies planas foram efetuadas sete medições, o que foi considerado equivalente a sete espécimes. No método do disco retificado, cada espécime de resina composta era confeccionado diretamente numa cavidade semicircular, localizada na periferia de um disco-suporte; os espécimes de PMMA consistiam em discos constituídos exclusivamente por este material; o desgaste de cada espécime era promovido por um disco de porcelana e seu conseqüente deslocamento era detectado por um palpador; assim, a taxa de desgaste era estabelecida, expressa em milímetros cúbicos por newton por segundo (mm3/N.s). No método de escovação, cada espécime cilíndrico ficava preso numa placa metálica, a qual era fixada no interior da máquina de escovação; sua perda de massa (em miligramas) era verificada através de uma balança analítica. No método do nanodurômetro, existiu apenas um espécime ci líndrico para cada condição, em cuja face plana superior eram feitos sete sulcos (equivalentes a sete espécimes); o coeficiente de atrito permitia estabelecer a respectiva resistência ao desgaste. Para cada método utilizado, os dados foram tratados estatisticamente, através de análise de variância (ANOVA) e de teste de Tukey. Pôde-se concluir que, através do disco retificado, a taxa de desgaste (em mm3/N.s) dos materiais foi: Incisal (0,6807) > C4 (0,5012) > PMMA (0,1439); que, através da escovação, a taxa de desgaste (em mg) foi de 5,40 para Incisal, de 9,35 para C4 e de 5,88 para PMMA, sem diferença significante apenas entre Incisal e PMMA, os mais resistentes; e que, através do nanodurômtero, a resistência ao desgaste abrasivo (expressa pelo coeficiente de atrito) foi de 0,207 para Incisal, de 0,214 para C4 e de 0,281 para PMMA, sem diferença significante agora apenas entre Incisal e C4, os menos resistentes. / Abrasive wear of a composite resin, using three different methods (ground disc, toothbrushing and nanodurometer). The aim at this study was to evaluate the resistance to abrasive wear of a composite resin, using three different methods: ground disc, toothbrushing and nanodurometer. At the first two methods were employed 20 specimens of Filtek Z250 composite resin (10 of Incisal and 10 of C4, both the colors cured for 30 seconds each one) and 10 of polymethylmethacrylate (PMMA), the latter acting as a reference standard. For the tests with the nanodurometer it was used only one specimen of each color, as well as just one of PMMA, in whose flat surfaces seven measurements were made, what was considered equivalent to seven specimens. At the ground disc method, each composite resin specimen was directly made on a semicircular cavity located on the periphery of a supporting disc; PMMA specimens consisted of discs made up exclusively with this material; the wear of each specimen was promoted by a ceramic disc and its consequent displacement was detected by a sensor; thus, the wear rate was established, expressed in cubic millimeters per newton per second (mm3/N.s). At the toothbrushing method, each cylindrical specimen was trapped in a metal plate, which was fixed inside the machine brushing; its weight loss (in milligrams) was verified by an analytical balance. At the nanodurometer method, there was only one cylindrical specimen for each condition, in whose flat upper face seven grooves were made (what was equivalent to seven specimens); the coefficient of friction was used to establish its wear resistance. For each method, data were statistically analyzed by ANOVA and Tukey\'s test. It could be concluded that, by ground disc method, materials wear rate (in mm3/N.s) was Incisal (0.6807) > C4 (0.5012) > PMMA (0.1439); by brushing method, materials wear rate (in mg) was 5.40 for Incisal, 9.35 for C4 and 5.88 for PMMA, without significant difference only between Incisal and PMMA (the toughest); by nanodurometer method, abrasive wear resistance (expressed by the coefficient of friction) was 0.207 for Incisal, 0.214 for C4 and 0.281 for PMMA, now without significant difference just between Incisal and C4, the least resistant.
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In-vitro wear and hardness of new conventional glass ionomer cement coated with nano-filled resinAlJamhan, Abdullah Saleh January 2011 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Background: Since the introduction of glass ionomer cements (GICs) in the 1970s, many attempts have been made to improve them and expand their application in restorative dentistry. Recently, GC America introduced a new glass ionomer restorative system called EQUIA. The manufacturer claims that this material has improved wear resistance by coating the surface of high-strength GIC with a nano-filled resin coating. Objective: The objective of this study was to measure the wear resistance and hardness of EQUIA and to compare it to other current restorative materials. Materials and Methods: Four different materials were used in this study: EQUIA, Fuji IX GP Extra, Fuji II LC and Z-100. Six specimens of each material were made and then tested in a toothbrush abrasion machine for 20,400 cycles, after which the amount of volume loss was calculated. Eight specimens of each material were made and tested in a three-body Alabama wear testing machine under a load of 75 N for 400,000 cycles. Four surface profiles were obtained from each specimen and volume loss was calculated using computer software. Five specimens of each material were made and Knoop microhardness was determined by using the mean of the three values from the top surface of the specimen. Results of each test were collected and compared with the other materials using one-way analysis of variance (ANOVA) at a significance level of 0.05. Results: Wear-resistance results showed that EQUIA has wear-resistance values comparable to composite resin and higher values than those for the high-strength GIC. The results also showed that Fuji II LC had the highest wear among all tested materials. Microhardness results showed that EQUIA has significantly lower microhardness than Fuji IX GP Extra and Z-100. Conclusion: Based on the results of the present study, it can be concluded that coating the surface of glass ionomer restorations with a nano-filled resin coat results in increasing the wear resistance and decreasing the microhardness of the material. Within the limitations of this study, EQUIA has comparable wear resistance to composite resin.
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The effect of full-contour Y-TZP ceramic surface roughness on the wear of bovine enamel and synthetic hydroxyapatite : an in-vitro studySabrah, Alaá Hussein Aref, 1984- January 2011 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / THE EFFECT OF FULL-CONTOUR Y-TZP CERAMIC SURFACE ROUGHNESS ON THE WEAR OF BOVINE ENAMEL AND SYNTHETIC HYDROXYAPATITE:
AN IN-VITRO STUDY
by
Alaa Hussein Aref Sabrah
Indiana University School of Dentistry
Indianapolis, Indiana
Full-contour yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) restorations have been advocated recently in clinical situations where occlusal/palatal space is limited, or to withstand parafunctional activities. The objectives of this in-vitro study were to investigate the effects of different polishing techniques on the surface roughness of Y-TZP (Ardent Dental, Inc.) and to investigate the effects of different polishing techniques on the wear behavior of synthetic hydroxyapatite (HA) and bovine enamel.
An in-vitro study was conducted by fabrication of 48 Y-TZP sliders (diameter = 2 mm × 1.5 mm in height) using CAD/CAM technique; then the samples were embedded in acrylic resin using brass holders. Samples were then randomly allocated into four groups according to the finishing/polishing procedure: G1-as-machined (n = 8), G2-
glazed (n = 16), G3-diamond bur-finishing (Brasseler, USA) (n = 8) and G4- G3+OptraFine polishing kit (Ivoclar-Vivadent) (n = 16). Thirty-two sintered HA disks (diameter = 11 mm × 2.9 mm in height) and 16 bovine enamel samples with a minimum surface area of 64 mm2 were mounted in brass holders. Baseline surface roughness (Ra and Rq, in μm) were recorded using a non-contact profilometer (Proscan 2000) for all the samples. A two-body pin-on-disk wear test was performed for 25,000 cycles at 1.2 Hz in which the four zirconia groups were tested against HA, and only G2-glazed and G4- G3+OptraFine polishing kit (Ivoclar-Vivadent) were tested against bovine enamel. Vertical substance loss (μm) and volume loss (mm3) of HA were measured (Proscan). Zirconia height loss was measured using a digital micrometer. One-way ANOVA was used for statistical analysis.
The results indicated that surface roughness measurements showed significant differences among the surface treatments with G1 (Ra = 0.84, Rq = 1.13 μm) and G3 (Ra
= 0.89, Rq = 1.2 μm) being the roughest, and G2 (Ra = 0.42, Rq = 0.63 μm) the smoothest. The glazed group showed the highest vertical loss (35.39 μm) suggesting
wear of the glaze layer, while the polished group showed the least vertical loss (6.61 μm). HA antagonist volume loss and vertical height loss for groups (G1, G2 and G3) were similar, while polished group (1.3 mm3, 14.7 μm) showed significant lower (p = 0.0001) values. Antagonist height loss and antagonist volume loss were significantly higher for bovine antagonist than for HA antagonist (197.6 μm/116.2 μm, and 28.5 mm3/17.7 mm3 for bovine against glazed/polished zirconia sliders, respectively) (p < 0.0001).
From the results it can be concluded that glazed zirconia provided an initially smooth surface, but a significant increased antagonist wear compared with the polished surface was seen.
Bovine enamel showed higher wear compared with HA, which suggested that more studies should be performed to validate the use of bovine enamel as a substitute for human enamel in wear studies.
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