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Lidija Ćurković - One of the best experts on this subject based on the ideXlab platform.
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Vickers indentation fracture toughness of Y-TZP Dental Ceramics
International Journal of Refractory Metals & Hard Materials, 2017Co-Authors: Danko Ćorić, Marijana Majić Renjo, Lidija ĆurkovićAbstract:Abstract The purpose of this study was to investigate and analyse the fracture toughness of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) Dental Ceramics by means of the Vickers indentation technique. Indentation tests are commonly used for the evaluation of the fracture toughness of brittle materials, particularly glass and Ceramics, because this technique requires a small sample from which a large number of data points can be generated rapidly. However, a wide variety of equations for the evaluation of the fracture toughness by means of Vickers indentation are available. Therefore, it is important to choose the most appropriate model for the description of this Ceramics' fracture behavior. In the present work, nine different fracture toughness equations are considered and the results are compared with the literature value obtained by a conventional method, single edge V-notched beam (SEVNB) test. The influence of the applied indentation load on fracture toughness was also observed. Tests were conducted under four different loading conditions (29.42 N, 49.03 N, 196.13 N, and 294.20 N). Obtained results indicate that the fracture toughness of Y-TZP Dental Ceramics depends on the indentation load, morphology of indentation cracking as well as on the applied model of fracture resistance.
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Indentation size effect of Y-TZP Dental Ceramics
Dental Materials, 2014Co-Authors: Marijana Majić Renjo, Lidija Ćurković, Sanja Štefančić, Danko ĆorićAbstract:Abstract Objective The purpose of this study was to investigate and analyze the indentation size effect (ISE) in Vickers hardness of monolithic yttria partially stabilized zirconia (Y-TZP) Dental Ceramics without and with the addition of Dental dye A3. The ISE is analyzed using the Mayer law, a proportional specimen resistance (PSR) model and a modified proportional specimen resistance (MPSR) model. Methods Two samples of Y-TZP Dental Ceramics, trade names BruxZir (provided by Glidewell Laboratories, CA, USA), were investigated. The first sample was polished Y-TZP and the second sample was polished Y-TZP with the addition of Dental dye A3, by VITA Classical Shade Guide. The Vickers hardness was measured under the following loads: 0.49 N, 0.98 N, 1.96 N, 4.90, 9.81 N and 29.42 N. Thirty indentations were made on each sample, under each load. Relationships between the applied load, F, and the resulting indentation size, d, have been analyzed by the Mayer law, the PSR model and the MPSR model. Results The Meyer index (n) for both Y-TZP Dental Ceramics is less than 2, which indicates that hardness is dependent on test loads. The PSR model and the MPSR model were used to calculate “true” Vickers hardness or load-independent hardness. Significance All applied mathematical models are suitable for the data analysis, which is confirmed with high correlation coefficients, but the best correlation between measured values and mathematical models was achieved with the MPSR model with a correlation coefficient of 0.9999.
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Investigation of Glazed Y-TZP Dental Ceramics Corrosion by Surface Roughness Measurement
Acta stomatologica Croatica, 2013Co-Authors: Sanja Štefančić, Lidija Ćurković, Gorana Baršić, Marijana Majić-renjo, Ketij MehulićAbstract:Introduction: Among Dental applications, the zirconia based Ceramics are widespread because of their general properties. The changes in superficial surface roughness correspond to the structural changes in the material caused by the influence of corrosion. The aim of this study was to determine chemical stability of glazed Y-TZP using surface roughness measurements. Materials and methods: Five samples of Y-TZP material BruxZir (Glidewell Laboratories © 2012.) with the addition of pigment A3 were sintered, polished and glazed to imitate the finishing process in producing monolithic crowns. After determining the mass of the sample, each sample was immersed in 10 ml of 4 wt. % CH3COOH aqueous solution. The roughness was measured five times before and after immersion. Results: All measured roughness parameters have significantly increased, showing higher penetration depth in all surface areas after immersion in 4 wt. % CH3COOH aqueous solution compared to the initial values. Weight loss of investigated Dental Ceramics samples was 2.45 mg/cm2 ± 0.026. Conclusion: Highly acidic conditions augment surface roughness of Y-TZP glazed Dental Ceramics.
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COPARISON OF SURFACE ROUGHNESS OF Dental Ceramics BEFORE AND AFTER ACID MEDIUM EXPOSURE
2005Co-Authors: Marko Jakovac, Lidija Ćurković, Sanjin Mahović, Jasenka Živko-babićAbstract:Dental Ceramics are considered to be chemically inert. However, influence of oral cavity could change its surface roughness. The aim of this study was to investigate the surface roughness before and after acid medium exposure of two different types of Dental Ceramics. The samples were made of feldspathic ceramic and glass- ceramic. The roughness of each sample was measured on three spots before and after exposure to 4 % solution of acetic acid. The results showed that only feldspathic ceramic had significant difference in surface roughness after acid exposure. The results in this study were very similar to those found in literature. The main reason for different reaction to acid medium is different microstructure of glass- and feldspathic ceramic. It could be concluded that glass-ceramic had better inertness to acid exposure and therefore it is more biocompatible then feldspathic ceramic.
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Estimation of Wear Resistance in Acid Solution of Dental Ceramics by Neural Network
Acta stomatologica Croatica, 2002Co-Authors: Dragutin Lisjak, Jasenka Živko-babić, Lidija Ćurković, Marko JakovacAbstract:It is known that exposure to acid cause damage to the glass surface. The aim of this study was to examine wear resistance, measuring the mass change of Dental Ceramics after contact with 10-3 mol dm-3 HCl at temperature of 50 oC. Four samples of Dental Ceramics were analyzed: feldspatic ceramic, hydrothermal ceramic, glass ceramic for staining and glass ceramic for layering. The mass concentrations of eluted Na+, K+ and Ca2+ were determined by ion chromatography (IC) and mass concentrations of Si4+ and Al3+ by UV/VIS spectrometry. The measurements were conducted after 1, 2, 3, 6 and 12 months of emersion. For the subject issue, using experimental data, the feedforward backpropagation neural network for estimation of wear resistance of Dental Ceramics has been modeled. The results of 1, 2 and 12 months of emersion were used for the training 13-20-5 model of neural network. Comparison of experimental data and data obtained by estimation (results of 3 and 6 months interval time) of neural network shows that applied network model provides very good prediction of wear behavior of Dental Ceramics with high correlation coefficient (R) and low sum of squared error (SSE) between measurement and estimated output values.
Danko Ćorić - One of the best experts on this subject based on the ideXlab platform.
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Critical evaluation of indentation fracture toughness measurements with Vickers indenter on yttria‐stabilized zirconia Dental Ceramics
Materialwissenschaft Und Werkstofftechnik, 2017Co-Authors: Danko Ćorić, Marijana Majić Renjo, Irena ŽmakAbstract:The purpose of this study was to investigate and analyze fracture toughness (KIc) of yttria stabilized tetragonal zirconia (Y-TZP) Dental Ceramics by the Vickers indentation fracture test. In order to determine fracture toughness, the Vickers indenter was used under the load of 294.20 N (HV30). The cracks, which occur from the corners of a Vickers indentation, were measured and used for fracture toughness determination, through five mathematical models according to (I) Anstis, (II) Evans and Charles, (III) Tanaka, (IV) Niihara, Morena and Hasselman and (V) Lankford. Morphology of indentation cracking was determined by scanning electron microscope. The most adequate model for determination of fracture toughness (KIc) of yttria stabilized tetragonal zirconia Dental Ceramics by the Vickers indentation fracture test is Lankford model.
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Vickers indentation fracture toughness of Y-TZP Dental Ceramics
International Journal of Refractory Metals & Hard Materials, 2017Co-Authors: Danko Ćorić, Marijana Majić Renjo, Lidija ĆurkovićAbstract:Abstract The purpose of this study was to investigate and analyse the fracture toughness of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) Dental Ceramics by means of the Vickers indentation technique. Indentation tests are commonly used for the evaluation of the fracture toughness of brittle materials, particularly glass and Ceramics, because this technique requires a small sample from which a large number of data points can be generated rapidly. However, a wide variety of equations for the evaluation of the fracture toughness by means of Vickers indentation are available. Therefore, it is important to choose the most appropriate model for the description of this Ceramics' fracture behavior. In the present work, nine different fracture toughness equations are considered and the results are compared with the literature value obtained by a conventional method, single edge V-notched beam (SEVNB) test. The influence of the applied indentation load on fracture toughness was also observed. Tests were conducted under four different loading conditions (29.42 N, 49.03 N, 196.13 N, and 294.20 N). Obtained results indicate that the fracture toughness of Y-TZP Dental Ceramics depends on the indentation load, morphology of indentation cracking as well as on the applied model of fracture resistance.
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Indentation size effect of Y-TZP Dental Ceramics
Dental Materials, 2014Co-Authors: Marijana Majić Renjo, Lidija Ćurković, Sanja Štefančić, Danko ĆorićAbstract:Abstract Objective The purpose of this study was to investigate and analyze the indentation size effect (ISE) in Vickers hardness of monolithic yttria partially stabilized zirconia (Y-TZP) Dental Ceramics without and with the addition of Dental dye A3. The ISE is analyzed using the Mayer law, a proportional specimen resistance (PSR) model and a modified proportional specimen resistance (MPSR) model. Methods Two samples of Y-TZP Dental Ceramics, trade names BruxZir (provided by Glidewell Laboratories, CA, USA), were investigated. The first sample was polished Y-TZP and the second sample was polished Y-TZP with the addition of Dental dye A3, by VITA Classical Shade Guide. The Vickers hardness was measured under the following loads: 0.49 N, 0.98 N, 1.96 N, 4.90, 9.81 N and 29.42 N. Thirty indentations were made on each sample, under each load. Relationships between the applied load, F, and the resulting indentation size, d, have been analyzed by the Mayer law, the PSR model and the MPSR model. Results The Meyer index (n) for both Y-TZP Dental Ceramics is less than 2, which indicates that hardness is dependent on test loads. The PSR model and the MPSR model were used to calculate “true” Vickers hardness or load-independent hardness. Significance All applied mathematical models are suitable for the data analysis, which is confirmed with high correlation coefficients, but the best correlation between measured values and mathematical models was achieved with the MPSR model with a correlation coefficient of 0.9999.
C. Treadwell - One of the best experts on this subject based on the ideXlab platform.
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Rotary Ultrasonic Machining of Alumina Dental Ceramics: A Preliminary Experimental Study on Surface and Subsurface Damages
Journal of Manufacturing Science and Engineering-transactions of The Asme, 2012Co-Authors: Yasser Ahmed, Zhijian Pei, C. Treadwell, Weilong Cong, Matthew R. Stanco, Y. L. ZhuAbstract:This paper presents a preliminary study about effects of ultrasonic vibration on machined surface and subsurface damages in rotary ultrasonic machining (RUM). The surface and subsurface damages are compared for machining of Dental Ceramics (Al2O3) with and without ultrasonic vibration. The surface chippings are evaluated and the subsurface cracks are observed under scanning electron microscope (SEM).
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Rotary Ultrasonic Machining of Dental Ceramics: A Preliminary Study on Subsurface Cracks
Journal of Medical Devices-transactions of The Asme, 2010Co-Authors: Weilong Cong, Zhijian Pei, Matthew R. Stanco, C. TreadwellAbstract:Commercially available Dental computer aided design/computer aided manufacture (CAD/CAM) systems usually use abrasive machining processes such as diamond grinding and milling. One of the major disadvantages of abrasive machining processes is subsurface cracks. In the present paper, rotary ultrasonic machining (RUM) technology is introduced into machining of alumina Dental Ceramics. The subsurface cracks are observed under scanning electron microscope. Effects of ultrasonic vibration on the subsurface cracks are also investigated. Results show that RUM is a very promising process to significantly reduce subsurface cracks in CAD/CAM of Dental Ceramics.
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Rotary ultrasonic machining of Dental Ceramics
International Journal of Machining and Machinability of Materials, 2009Co-Authors: N. J. Churi, Zhijian Pei, D.c. Shorter, C. TreadwellAbstract:Dental Ceramics are used for a number of aesthetic and prostheses applications due to their high compressive strength, superior wear resistance and natural aesthetical appearance. However, their cost-effective machining still remains a challenge. This paper reports an experimental study on machining of one type of Dental Ceramics (macor) with rotary ultrasonic machining (RUM). Effects of process parameters (spindle speed, feed rate and ultrasonic vibration power) on the cutting force, surface roughness, and chipping size are obtained.
Marijana Majić Renjo - One of the best experts on this subject based on the ideXlab platform.
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Critical evaluation of indentation fracture toughness measurements with Vickers indenter on yttria‐stabilized zirconia Dental Ceramics
Materialwissenschaft Und Werkstofftechnik, 2017Co-Authors: Danko Ćorić, Marijana Majić Renjo, Irena ŽmakAbstract:The purpose of this study was to investigate and analyze fracture toughness (KIc) of yttria stabilized tetragonal zirconia (Y-TZP) Dental Ceramics by the Vickers indentation fracture test. In order to determine fracture toughness, the Vickers indenter was used under the load of 294.20 N (HV30). The cracks, which occur from the corners of a Vickers indentation, were measured and used for fracture toughness determination, through five mathematical models according to (I) Anstis, (II) Evans and Charles, (III) Tanaka, (IV) Niihara, Morena and Hasselman and (V) Lankford. Morphology of indentation cracking was determined by scanning electron microscope. The most adequate model for determination of fracture toughness (KIc) of yttria stabilized tetragonal zirconia Dental Ceramics by the Vickers indentation fracture test is Lankford model.
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Vickers indentation fracture toughness of Y-TZP Dental Ceramics
International Journal of Refractory Metals & Hard Materials, 2017Co-Authors: Danko Ćorić, Marijana Majić Renjo, Lidija ĆurkovićAbstract:Abstract The purpose of this study was to investigate and analyse the fracture toughness of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) Dental Ceramics by means of the Vickers indentation technique. Indentation tests are commonly used for the evaluation of the fracture toughness of brittle materials, particularly glass and Ceramics, because this technique requires a small sample from which a large number of data points can be generated rapidly. However, a wide variety of equations for the evaluation of the fracture toughness by means of Vickers indentation are available. Therefore, it is important to choose the most appropriate model for the description of this Ceramics' fracture behavior. In the present work, nine different fracture toughness equations are considered and the results are compared with the literature value obtained by a conventional method, single edge V-notched beam (SEVNB) test. The influence of the applied indentation load on fracture toughness was also observed. Tests were conducted under four different loading conditions (29.42 N, 49.03 N, 196.13 N, and 294.20 N). Obtained results indicate that the fracture toughness of Y-TZP Dental Ceramics depends on the indentation load, morphology of indentation cracking as well as on the applied model of fracture resistance.
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Indentation size effect of Y-TZP Dental Ceramics
Dental Materials, 2014Co-Authors: Marijana Majić Renjo, Lidija Ćurković, Sanja Štefančić, Danko ĆorićAbstract:Abstract Objective The purpose of this study was to investigate and analyze the indentation size effect (ISE) in Vickers hardness of monolithic yttria partially stabilized zirconia (Y-TZP) Dental Ceramics without and with the addition of Dental dye A3. The ISE is analyzed using the Mayer law, a proportional specimen resistance (PSR) model and a modified proportional specimen resistance (MPSR) model. Methods Two samples of Y-TZP Dental Ceramics, trade names BruxZir (provided by Glidewell Laboratories, CA, USA), were investigated. The first sample was polished Y-TZP and the second sample was polished Y-TZP with the addition of Dental dye A3, by VITA Classical Shade Guide. The Vickers hardness was measured under the following loads: 0.49 N, 0.98 N, 1.96 N, 4.90, 9.81 N and 29.42 N. Thirty indentations were made on each sample, under each load. Relationships between the applied load, F, and the resulting indentation size, d, have been analyzed by the Mayer law, the PSR model and the MPSR model. Results The Meyer index (n) for both Y-TZP Dental Ceramics is less than 2, which indicates that hardness is dependent on test loads. The PSR model and the MPSR model were used to calculate “true” Vickers hardness or load-independent hardness. Significance All applied mathematical models are suitable for the data analysis, which is confirmed with high correlation coefficients, but the best correlation between measured values and mathematical models was achieved with the MPSR model with a correlation coefficient of 0.9999.
Zhijian Pei - One of the best experts on this subject based on the ideXlab platform.
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Rotary Ultrasonic Machining of Alumina Dental Ceramics: A Preliminary Experimental Study on Surface and Subsurface Damages
Journal of Manufacturing Science and Engineering-transactions of The Asme, 2012Co-Authors: Yasser Ahmed, Zhijian Pei, C. Treadwell, Weilong Cong, Matthew R. Stanco, Y. L. ZhuAbstract:This paper presents a preliminary study about effects of ultrasonic vibration on machined surface and subsurface damages in rotary ultrasonic machining (RUM). The surface and subsurface damages are compared for machining of Dental Ceramics (Al2O3) with and without ultrasonic vibration. The surface chippings are evaluated and the subsurface cracks are observed under scanning electron microscope (SEM).
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Rotary Ultrasonic Machining of Dental Ceramics: A Preliminary Study on Subsurface Cracks
Journal of Medical Devices-transactions of The Asme, 2010Co-Authors: Weilong Cong, Zhijian Pei, Matthew R. Stanco, C. TreadwellAbstract:Commercially available Dental computer aided design/computer aided manufacture (CAD/CAM) systems usually use abrasive machining processes such as diamond grinding and milling. One of the major disadvantages of abrasive machining processes is subsurface cracks. In the present paper, rotary ultrasonic machining (RUM) technology is introduced into machining of alumina Dental Ceramics. The subsurface cracks are observed under scanning electron microscope. Effects of ultrasonic vibration on the subsurface cracks are also investigated. Results show that RUM is a very promising process to significantly reduce subsurface cracks in CAD/CAM of Dental Ceramics.
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Rotary ultrasonic machining of Dental Ceramics
International Journal of Machining and Machinability of Materials, 2009Co-Authors: N. J. Churi, Zhijian Pei, D.c. Shorter, C. TreadwellAbstract:Dental Ceramics are used for a number of aesthetic and prostheses applications due to their high compressive strength, superior wear resistance and natural aesthetical appearance. However, their cost-effective machining still remains a challenge. This paper reports an experimental study on machining of one type of Dental Ceramics (macor) with rotary ultrasonic machining (RUM). Effects of process parameters (spindle speed, feed rate and ultrasonic vibration power) on the cutting force, surface roughness, and chipping size are obtained.