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Her-hsiung Huang - One of the best experts on this subject based on the ideXlab platform.

  • improvement in Dental Porcelain bonding to milled noncast titanium surfaces by gold sputter coating
    Journal of Prosthodontics, 2014
    Co-Authors: Her-hsiung Huang
    Abstract:

    PURPOSE: This study evaluated the adherence of Dental Porcelain to a milled, noncast titanium (Ti) surface with a gold sputter coating to evaluate a possible new practical surface treatment for enhancing the bond strength between Ti and Porcelain. MATERIALS AND METHODS: Milled, noncast Ti strips were created by computer-aided design and manufacturing processes. The milled, noncast Ti strips were sandblasted with alumina particles and were then sequentially subjected to gold sputter coating treatments of 150- and 300-second duration. Low-fusion Dental Porcelain was then sintered onto the surface-treated Ti strips. The bond strengths of the Ti/Porcelain specimens were evaluated using a three-point bending test (ISO 9693). Surface characterizations of the specimens were carried out with X-ray photoelectron spectrometry, scanning electron microscopy, and energy dispersive X-ray spectroscopy. RESULTS: The results indicated that the bond strengths of all the Ti/Porcelain groups were greater than the minimum requirement (25 MPa) as prescribed by ISO 9693. The gold sputter coating increased the oxidation resistance (or decreased the oxide content) of the Ti surface during Porcelain sintering, which positively affected the bond strength of Ti/Porcelain (approximately 36 MPa) compared to the untreated Ti/Porcelain specimen (approximately 29 MPa). The fracture morphologies of all the Ti/Porcelain groups revealed an adhesive bond failure as the interfacial fracture mode between the Ti and the Porcelain. CONCLUSIONS: A practical and simple sandblasting/gold sputter coating treatment of Ti surfaces prior to Porcelain sintering significantly strengthens the bond between the milled, noncast Ti and the Dental Porcelain.

  • Bonding of Dental Porcelain to non-cast titanium with different surface treatments.
    Dental Materials Journal, 2012
    Co-Authors: Kuo-lung Tung, Her-hsiung Huang
    Abstract:

    : This study investigated the bonding of Dental Porcelain to non-cast Ti surface with different treatments. Mechanically ground non-cast Ti strips, simulating surface conditions produced by CAD/CAM, were Al(2)O(3)-sandblasted, then subjected to different surface treatments, including immersion in HNO(3)-containing acid, NaOH-containing alkaline, and NaOH-containing alkaline then HNO(3)-containing acid. Ti-Porcelain specimens preparations and their bend strength measurements were based on ISO 9693. Ti surface treatment changed not only surface roughness but also surface chemistry, leading to influence on bond strength. Bond strengths of all Ti-Porcelain groups were higher than ISO 9693 minimum requirement. The sandblasted/acid-treated Ti surface showed the highest bond strength (34.60 MPa) with Porcelain; no significant difference in bond strength (27.92-29.63 MPa) was found among other TiPorcelain groups. All Ti-Porcelain specimens showed adhesive bond failure. Bonding between non-cast Ti and Dental Porcelain was strengthened by a simple and practical sandblasting/acid-etching treatment of the Ti surface prior to Porcelain sintering.

Amalia L Evans - One of the best experts on this subject based on the ideXlab platform.

  • quantitative x ray diffraction determination of leucite thermal instability in Dental Porcelain
    Journal of the American Ceramic Society, 1991
    Co-Authors: Rodway J Mackert, Amalia L Evans
    Abstract:

    Alterations in the leucite content of Dental Porcelain during thermal treatments required for fabrication of Dental restorations produce proportional changes in the thermal expansion coefficient. Such thermal expansion changes can create a thermal expansion mismatch with the metal to which it is fused and can result in the fracture of the Porcelain during fabrication. The purpose of this study was to determine whether changes in the leucite content of a Dental Porcelain resulting from thermal treatments could be detected via quantitative X-ray diffraction. The thermal treatments investigated were isothermal soaks for 0, 4, 8, and 16 min at 500° and 750°C, or multiple firings of 1, 2, 4, 8, and 16 times. Quantitative X-ray diffraction was performed on the heat-treated Porcelain specimens, and the data were subjected to linear regression analysis. A significant negative correlation (r=−0.92, p < 0.001) was found between leucite volume fraction and the number of firings. A significant positive correlation (r= 0.88, p < 0.001) was obtained between leucite volume fraction and duration of heat soak at 750°C. No relationship was found (r= 0.40, p= 0.127) between the leucite content and the duration of the heat soak at 500°C. Such leucite variations could be responsible for changes in Porcelain—metal thermal compatibility.

  • Quantitative X‐ray Diffraction Determination of Leucite Thermal instability in Dental Porcelain
    Journal of the American Ceramic Society, 1991
    Co-Authors: J. Rodway Mackert, Amalia L Evans
    Abstract:

    Alterations in the leucite content of Dental Porcelain during thermal treatments required for fabrication of Dental restorations produce proportional changes in the thermal expansion coefficient. Such thermal expansion changes can create a thermal expansion mismatch with the metal to which it is fused and can result in the fracture of the Porcelain during fabrication. The purpose of this study was to determine whether changes in the leucite content of a Dental Porcelain resulting from thermal treatments could be detected via quantitative X-ray diffraction. The thermal treatments investigated were isothermal soaks for 0, 4, 8, and 16 min at 500° and 750°C, or multiple firings of 1, 2, 4, 8, and 16 times. Quantitative X-ray diffraction was performed on the heat-treated Porcelain specimens, and the data were subjected to linear regression analysis. A significant negative correlation (r=−0.92, p < 0.001) was found between leucite volume fraction and the number of firings. A significant positive correlation (r= 0.88, p < 0.001) was obtained between leucite volume fraction and duration of heat soak at 750°C. No relationship was found (r= 0.40, p= 0.127) between the leucite content and the duration of the heat soak at 500°C. Such leucite variations could be responsible for changes in Porcelain—metal thermal compatibility.

Mariusz Walczak - One of the best experts on this subject based on the ideXlab platform.

  • the influence of sio2 and sio2 tio2 intermediate coatings on bond strength of titanium and ti6al4v alloy to Dental Porcelain
    Dental Materials, 2009
    Co-Authors: Jaroslaw Bieniaś, Barbara Surowska, Anna Stoch, Halina Matraszek, Mariusz Walczak
    Abstract:

    Abstract Objectives The purpose of this study was to evaluate the bond strength of commercially pure CPTi and Ti6Al4V alloy with SiO 2 and SiO 2 –TiO 2 intermediate coatings to Triceram low-fusing Dental Porcelain. Methods The multilayered systems were characterized from the standpoint of microstructure analysis (SEM), the mode of failure, the nature of bonding and the influence of intermediate coatings on the improvement of bond strength. The SiO 2 and SiO 2 –TiO 2 intermediate coatings were applied on the substrate materials by the sol–gel dipping technique. The metal–ceramic bond strength was investigated according to ISO 9693 standards using the three-point flexure bond test. Results Statistically significant higher bond strength of the metal–Porcelain for Ti6A14V alloy (28.24 MPa), Ti6Al4V/SiO 2 (32.17 MPa) and Ti6Al4V/SiO 2 –TiO 2 (36.09 MPa) was noted in comparison to CPTi (23.04 MPa), CPTi/SiO 2 (27.98 MPa) and CPTi/SiO 2 –TiO 2 (28.84 MPa), respectively. The nature of metal-intermediate coating–Porcelain bonding was both mechanical and chemical. The failure in all systems was cohesive and adhesive, mainly adhesive. Significance The application of SiO 2 and SiO 2 –TiO 2 intermediate coatings, produced by the sol–gel method, to both CPTi and Ti6Al4V alloy significantly improves the bond strength of metal–Porcelain systems in comparison to the metal substrate only after sandblasting, and may have clinical use.

Paulo Francisco Cesar - One of the best experts on this subject based on the ideXlab platform.

  • effect of fiber addition on slow crack growth of a Dental Porcelain
    Journal of The Mechanical Behavior of Biomedical Materials, 2015
    Co-Authors: M D Araujo, H N Yoshimura, Ranulfo Benedito De Paula Miranda, Catia Fredericci, Paulo Francisco Cesar
    Abstract:

    Abstract Aims To evaluate the effect of the processing method (conventional sintering, S, and heat-pressing, HP) and addition of potassium titanate fibers, PTF, on the microstructure, mechanical properties (flexural strength, σ f , and Weibull parameters, m and σ 5% ), slow crack growth parameters n (stress corrosion susceptibility coefficient), and optical properties (translucency parameter, TP, and opalescence index, OI) of a feldsphatic Dental Porcelain. Methods Disks ( n =240, O12×1 mm) of Porcelain (Vintage-Halo, Shofu) were produced using S and HP methods with and without addition of 10 wt% (conventional sintering) or 5 wt% (heat-pressing) of PTF. For the S method, Porcelain was sintered in a conventional furnace. In the HP technique, refractory molds were produced by lost wax technique. The Porcelain slurry was dry-pressed (3 t/30 s) to form a cylinder with 12 mm (diameter) and 20 mm (height), which was heat-pressed for 5 min/3.5 bar into the mold. Specimens were tested for biaxial flexural strength in artificial saliva at 37 °C. Weibull analysis was used to determine m and σ 5% . Slow crack growth (SCG) parameters were determined by the dynamic fatigue test, and specimens were tested in biaxial flexure at five stress rates: 10 −2 , 10 −1 , 10 0 , 10 1 and 10 2  MPa/s ( n =10), immersed in artificial saliva at 37 °C. Parameter n was calculated and statistically analyzed according to ASTM F394-78. Optical properties were determined in a spectrophotometer in the diffuse reflectance mode. Results The highest n value was obtained by the combination of heat-pressing with fiber addition (37.1) and this value was significantly higher than those obtained by both sintered groups (26.2 for control group and 27.7 for sintered with fiber). Although heat-pressing alone also resulted in higher n values compared to the sintered groups, there were no significant differences among them. Fiber addition had no effect on mechanical strength, but it resulted in decreased TP values and increased OI values for both processing methods. Heat-pressing alone was able to reduce the porosity level of the Porcelain. Conclusions Addition of PTF combined with heat-pressing can reduce strength degradation of a Dental Porcelain compared to sintered materials with or without fibers. Heat-pressing (HP) alone should be considered as a good alternative for clinical cases where high translucency is required.

  • effect of ion exchange on r curve behavior of a Dental Porcelain
    Journal of Materials Science, 2011
    Co-Authors: Paulo Francisco Cesar, H N Yoshimura, Vinicius Rosa, Marcelo Mendes Pinto, Luoyu Roy Xu
    Abstract:

    The objective of this study was to evaluate the effect of the ion exchange treatment on the R-curve behavior of a leucite-reinforced Dental Porcelain, testing the hypothesis that the ion exchange is able to improve the R-curve behavior of the Porcelain studied. Porcelain disks were sintered, finely polished, and submitted to an ion exchange treatment with a KNO3 paste. The R-curve behavior was assessed by fracturing the specimens in a biaxial flexure design after making Vickers indentations in the center of the polished surface with loads of 1.8, 3.1, 4.9, 9.8, 31.4, and 49.0 N. The results showed that the ion exchange process resulted in significant improvements in terms of fracture toughness and flexural strength as compared to the untreated material. Nevertheless, the rising R-curve behavior previously observed in the control group disappeared after the ion exchange treatment, i.e., fracture toughness did not increase with the increase in crack size for the treated group.

  • al2o3 gdalo3 fiber for Dental Porcelain reinforcement
    Journal of The Mechanical Behavior of Biomedical Materials, 2009
    Co-Authors: Igor Studart Medeiros, H N Yoshimura, Paulo Francisco Cesar, A C Hernandes
    Abstract:

    Abstract The aim of this study was to test the hypothesis that the addition of continuous or milled GdAlO 3 /Al 2 O 3 fibers to a Dental Porcelain increases its mechanical properties. Porcelain bars without reinforcement (control) were compared to those reinforced with long fibers (30 vol%). Also, disk specimens reinforced with milled fibers were produced by adding 0 (control), 5 or 10 vol% of particles. The reinforcement with continuous fibers resulted in significant increase in the uniaxial flexural strength from 91.5 to 217.4 MPa. The addition of varied amounts of milled fibers to the Porcelain did not significantly affect its biaxial flexural strength compared to the control group. SEM analysis showed that the interface between the continuous fiber and the Porcelain was free of defects. On the other hand, it was possible to note the presence of cracks surrounding the milled fiber/Porcelain interface. In conclusion, the reinforcement of the Porcelain with continuous fibers resulted in an efficient mechanism to increase its mechanical properties; however the addition of milled fibers had no significant effect on the material because the Porcelain was not able to wet the ceramic particles during the firing cycle.

  • effect of ion exchange on strength and slow crack growth of a Dental Porcelain
    Dental Materials, 2009
    Co-Authors: Vinicius Rosa, H N Yoshimura, Marcelo Mendes Pinto, Catia Fredericci, Paulo Francisco Cesar
    Abstract:

    Abstract Objectives To determine the effect of ion exchange on slow crack growth (SCG) parameters (n, stress corrosion susceptibility coefficient, and σf0, scaling parameter) and Weibull parameters (m, Weibull modulus, and σ0, characteristic strength) of a Dental Porcelain. Methods 160 Porcelain discs were fabricated according to manufacturer's instructions, polished through 1 μm and divided into two groups: GC (control) and GI (submitted to an ion exchange procedure using a KNO3 paste at 470 °C for 15 min). SCG parameters were determined by biaxial flexural strength test in artificial saliva at 37 °C using five constant stress rates (n = 10). 20 specimens of each group were tested at 1 MPa/s to determine Weibull parameters. The SPT diagram was constructed using the least-squares fit of the strength data versus probability of failure. Results Mean values of m and σ0 (95% confidence interval), n and σf0 (standard deviation) were, respectively: 13.8 (10.1 − 18.8) and 60.4 (58.5 − 62.2), 24.1 (2.5) and 58.1 (0.01) for GC and 7.4 (5.3 − 10.0) and 136.8 (129.1 − 144.7), 36.7 (7.3) and 127.9 (0.01) for GI. Fracture stresses (MPa) calculated using the SPT diagram for lifetimes of 1 day, 1 year and 10 years (at a 5% failure probability) were, respectively, 31.8, 24.9 and 22.7 for GC and 71.2, 60.6 and 56.9 for GI. Significance For the Porcelain tested, the ion exchange process improved strength and resistance to SCG, however, the material's reliability decreased. The predicted fracture stress at 5% failure probability for a lifetime of 10 years was also higher for the ion treated group.

Noriyuki Wakabayashi - One of the best experts on this subject based on the ideXlab platform.

  • evaluation of the shear bond strength of Dental Porcelain and the low magnetic susceptibility zr 14nb alloy
    Journal of The Mechanical Behavior of Biomedical Materials, 2016
    Co-Authors: Yuka Kajima, Atsushi Takaichi, Tohru Yasue, Hidekazu Takahashi, Takao Hanawa, Noriyuki Wakabayashi
    Abstract:

    Abstract The aim of this study was to investigate the bond strength of Dental Porcelain and the preheated Zr–14Nb alloy, and compare this strength with that of titanium. White oxide layers, which were predominantly composed of monoclinic zirconia, were formed on the preheated sample groups, and exhibited a greater roughness than the control samples. At the metal–ceramic interface, a greater Nb diffusion range was observed than in the control samples. The bond strengths of the samples subjected to 20 min preheating treatment were the lowest (33.6±3.2 MPa), which may be ascribed to the formation of a brittle thick oxide layer under excessive heat treatment. The samples subjected to this heat treatment for 5 min exhibited the highest mean bond strength (43.7±5.9 MPa), which was significantly higher than that of titanium (35.3±3.5 MPa). Thus, the Zr–14Nb alloy is a promising candidate for fixed Dental prosthesis, as long as the appropriate treatment conditions are adopted.