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Albert J. Feilzer - One of the best experts on this subject based on the ideXlab platform.
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Microtensile bond strength and impact energy of fracture of CAD-veneered Zirconia restorations
Journal of Prosthodontics, 2009Co-Authors: Moustafa N Aboushelib, Marcel De Kler, Jef M. Van Der Zel, Albert J. FeilzerAbstract:PURPOSE: With state-of-the-art CAD/CAM technology, the fabrication of large and complex Zirconia frameworks is just a click away. On the other hand, veneering of the frameworks is still operator-dependent. The aim of this work was to evaluate CAD veneering of Zirconia restorations in terms of Zirconia veneer bond strength and impact energy of fracture in a step towards complete automation of the fabrication process. MATERIALS AND METHODS: A new CAD/CAM system was used to fabricate a resin replica of the esthetic ceramic required to veneer a Zirconia framework. The replica was seated on the Zirconia framework and further processed using press-on technology. The bond strength between Zirconia and the CAD veneer was evaluated using microtensile bond strength test. The impact energy of fracture of the specimens was also investigated. Manually layered Zirconia specimens served as a control (alpha= 0.05). RESULTS: There was no significant difference in the microtensile bond strength between Zirconia and either of the used veneers (39 MPa). Even though the impact energy of fracture of the CAD-veneered and manually layered specimens was almost identical (0.13 J), the former demonstrated a cohesive fracture of the veneer, while the latter failed by delamination of the veneer ceramic. CONCLUSION: CAD veneering is a reliable method for veneering Zirconia restorations.
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Effect of Zirconia type on its bond strength with different veneer ceramics
Journal of Prosthodontics, 2008Co-Authors: Moustafa N Aboushelib, Cornelis J Kleverlaan, Albert J. FeilzerAbstract:Purpose: The bond strength between veneer ceramic and the Zirconia framework is the weakest component in the layered structure. This bond was proven to be sensitive to the surface finish of the framework material and to the type of the veneer ceramic and its method of application. New colored Zirconia frameworks were introduced to enhance the final esthetics of the layered all-ceramic restoration. The aim of this study was to investigate the effect of Zirconia type, white or colored, and its surface finish on the bond strength to two veneer ceramics. Materials and Methods: Five commercial Zirconia framework materials (Cercon white and yellow, Lava white and yellow, Procera Zirconia) received either of the following surface treatments: CAD/CAM milled surface, airborne-particle abrasion, and liner application. Two veneering ceramics were used to veneer the specimens: Noble Rondo and Ceram Express. The disc-shaped layered specimens were cut into microbars, and microtensile bond strength (MTBS) test was conducted. Structural and chemical differences between the white and colored frameworks were evaluated using scanning electron microscopy (SEM) and energy dispersive analysis. Two-way ANOVA and Tukey post hoc tests were used to analyze the data (p < 0.05 was considered significant). Results: The type of Zirconia framework had a significant effect on the core-veneer bond strength, which was material dependent. The bond strength to colored Zirconia was significantly weaker compared to white Zirconia frameworks. Different surface treatments had different effects on the core-veneer bond strength according to the Zirconia material used. Although no marked chemical differences between the examined Zirconia materials could be found, there were structural differences, especially between white and colored Zirconia and for different Zirconia frameworks of different manufacturers, which significantly affected core-veneer bond strength values. Conclusion: The addition of coloring pigments to Zirconia frameworks resulted in structural changes that require different surface treatment before veneering. To prevent delamination and chipping failures of Zirconia veneered restorations, careful selection of both framework and veneer ceramic materials, in addition to proper surface treatment, are essential for maintaining good bond strength. © 2008 by The American College of Prosthodontists.
Moustafa N Aboushelib - One of the best experts on this subject based on the ideXlab platform.
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Microtensile bond strength and impact energy of fracture of CAD-veneered Zirconia restorations
Journal of Prosthodontics, 2009Co-Authors: Moustafa N Aboushelib, Marcel De Kler, Jef M. Van Der Zel, Albert J. FeilzerAbstract:PURPOSE: With state-of-the-art CAD/CAM technology, the fabrication of large and complex Zirconia frameworks is just a click away. On the other hand, veneering of the frameworks is still operator-dependent. The aim of this work was to evaluate CAD veneering of Zirconia restorations in terms of Zirconia veneer bond strength and impact energy of fracture in a step towards complete automation of the fabrication process. MATERIALS AND METHODS: A new CAD/CAM system was used to fabricate a resin replica of the esthetic ceramic required to veneer a Zirconia framework. The replica was seated on the Zirconia framework and further processed using press-on technology. The bond strength between Zirconia and the CAD veneer was evaluated using microtensile bond strength test. The impact energy of fracture of the specimens was also investigated. Manually layered Zirconia specimens served as a control (alpha= 0.05). RESULTS: There was no significant difference in the microtensile bond strength between Zirconia and either of the used veneers (39 MPa). Even though the impact energy of fracture of the CAD-veneered and manually layered specimens was almost identical (0.13 J), the former demonstrated a cohesive fracture of the veneer, while the latter failed by delamination of the veneer ceramic. CONCLUSION: CAD veneering is a reliable method for veneering Zirconia restorations.
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Effect of Zirconia type on its bond strength with different veneer ceramics
Journal of Prosthodontics, 2008Co-Authors: Moustafa N Aboushelib, Cornelis J Kleverlaan, Albert J. FeilzerAbstract:Purpose: The bond strength between veneer ceramic and the Zirconia framework is the weakest component in the layered structure. This bond was proven to be sensitive to the surface finish of the framework material and to the type of the veneer ceramic and its method of application. New colored Zirconia frameworks were introduced to enhance the final esthetics of the layered all-ceramic restoration. The aim of this study was to investigate the effect of Zirconia type, white or colored, and its surface finish on the bond strength to two veneer ceramics. Materials and Methods: Five commercial Zirconia framework materials (Cercon white and yellow, Lava white and yellow, Procera Zirconia) received either of the following surface treatments: CAD/CAM milled surface, airborne-particle abrasion, and liner application. Two veneering ceramics were used to veneer the specimens: Noble Rondo and Ceram Express. The disc-shaped layered specimens were cut into microbars, and microtensile bond strength (MTBS) test was conducted. Structural and chemical differences between the white and colored frameworks were evaluated using scanning electron microscopy (SEM) and energy dispersive analysis. Two-way ANOVA and Tukey post hoc tests were used to analyze the data (p < 0.05 was considered significant). Results: The type of Zirconia framework had a significant effect on the core-veneer bond strength, which was material dependent. The bond strength to colored Zirconia was significantly weaker compared to white Zirconia frameworks. Different surface treatments had different effects on the core-veneer bond strength according to the Zirconia material used. Although no marked chemical differences between the examined Zirconia materials could be found, there were structural differences, especially between white and colored Zirconia and for different Zirconia frameworks of different manufacturers, which significantly affected core-veneer bond strength values. Conclusion: The addition of coloring pigments to Zirconia frameworks resulted in structural changes that require different surface treatment before veneering. To prevent delamination and chipping failures of Zirconia veneered restorations, careful selection of both framework and veneer ceramic materials, in addition to proper surface treatment, are essential for maintaining good bond strength. © 2008 by The American College of Prosthodontists.
Hideo Matsumura - One of the best experts on this subject based on the ideXlab platform.
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fracture resistance of single tooth implant supported Zirconia based indirect composite layered molar restorations
Clinical Oral Implants Research, 2014Co-Authors: Kohei Taguchi, Futoshi Komine, Ryosuke Fushiki, Shingo Kamio, Markus B Blatz, Hideo MatsumuraAbstract:Objectives This study evaluated the fracture resistance of single-tooth implant-supported Zirconia-based indirect composite-layered molar restorations. Material and methods Forty-four titanium abutments (GingiHue Post) were placed on dental implants (Osseotite Implant). Standardized single-tooth cement-retained implant-supported mandibular molar restorations were fabricated for each of four test groups (n = 11) as follows: porcelain-fused-to-metal crowns (PFM), Zirconia-based all-ceramic crowns (ZAC), Zirconia-based indirect composite-layered crowns primed with Estenia Opaque Primer for Zirconia frameworks (ZIC-E), and Zirconia-based indirect composite-layered crowns (ZIC). The crowns were luted with a glass-ionomer cement (Ketac Cem Easymix). Fracture resistance (N) was determined by force application of a perpendicular load to the crowns with a universal testing machine. One-way analysis of variance (ANOVA) and the Tukey's HSD test were used to assess differences in fracture resistance values (α = 0.05). Results Mean fracture resistances (SD) were 3.09 (0.22) kN, 3.11 (0.34) kN, 2.84 (0.21) kN, and 2.50 (0.36) kN for the PFM, ZAC, ZIC-E, and ZIC groups, respectively. Fracture resistance in the ZIC specimens was significantly lower (P < 0.044) than that in the other groups, which did not significantly differ. Conclusions The fracture resistance of single-tooth implant-supported Zirconia-based indirect composite-layered molar crowns primed with Estenia Opaque Primer for Zirconia frameworks (ZIC-E) is comparable to that of porcelain-fused-to-metal (PFM) and Zirconia-based all-ceramic (ZAC) restorations. Application of Estenia Opaque Primer to Zirconia ceramic framework provides superior fracture resistance in implant-supported Zirconia-based indirect composite-layered molar crowns.
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current status of Zirconia restoration
Journal of Prosthodontic Research, 2013Co-Authors: Takashi Miyazaki, Hideo Matsumura, Takashi Nakamura, Taira KobayashiAbstract:Abstract During the past decade, Zirconia-based ceramics have been successfully introduced into the clinic to fabricate fixed dental prostheses (FDPs), along with a dental computer-aided/computer-aided manufacturing (CAD/CAM) system. In this article (1) development of dental ceramics, (2) the current status of dental CAD/CAM systems, (3) CAD/CAM and Zirconia restoration, (4) bond between Zirconia and veneering ceramics, (5) bond of Zirconia with resin-based luting agents, (6) surface finish of Zirconia restoration and antagonist enamel wear, and (7) clinical evaluation of Zirconia restoration are reviewed. Yttria partially stabilized tetragonal Zirconia polycrystalline (Y-TZP) showed better mechanical properties and superior resistance to fracture than other conventional dental ceramics. Furthermore, ceria-stabilized tetragonal Zirconia polycrystalline and alumina nanocomposites (Ce-TZP/A) had the highest fracture toughness and had resistance to low-temperature aging degradation. Both Zirconia-based ceramics have been clinically available as an alternative to the metal framework for fixed dental prostheses (FDPs). Marginal adaptation of Zirconia-based FDPs is acceptable for clinical application. The most frequent clinical complication with Zirconia-based FDPs was chipping of the veneering porcelain that was affected by many factors. The mechanism for the bonding between Zirconia and veneering ceramics remains unknown. There was no clear evidence of chemical bonding and the bond strength between Zirconia and porcelain was lower than that between metal and porcelain. There were two alternatives proposed that might avoid chipping of veneering porcelains. One was hybrid-structured FDPs comprising CAD/CAM-fabricated porcelain parts adhering to a CAD/CAM fabricated Zirconia framework. Another option was full-contour Zirconia FDPs using high translucent Zirconia. Combined application of silica coating and/or silane coupler, and 10-methacryloyloxydecyl dihydrogen phosphate is currently one of the most reliable bonding systems for Zirconia. Adhesive treatments could be applied to luting the restorations and fabricating hybrid-structured FDPs. Full-contour Zirconia FDPs caused concern about the wear of antagonist enamel, because the hardness of Y-TZP was over double that of porcelain. However, this review demonstrates that highly polished Zirconia yielded lower antagonist wear compared with porcelains. Polishing of Zirconia is possible, but glazing is not recommended for the surface finish of Zirconia. Clinical data since 2010 are included in this review. The Zirconia frameworks rarely got damaged in many cases and complications often occurred in the veneering ceramic materials. Further clinical studies with larger sample sizes and longer follow-up periods are required to investigate the possible influencing factors of technical failures.
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Current status of Zirconia-based fixed restorations
Journal of Oral Science, 2010Co-Authors: Futoshi Komine, Markus B Blatz, Hideo MatsumuraAbstract:Zirconium dioxide (Zirconia) ceramics are currently used for fixed restorations as a framework material due to their mechanical and optical properties. This review article describes the current status of Zirconia-based fixed restorations, including results of current in vitro studies and the clinical performance of these restorations. Adaptation of Zirconia-based restorations fabricated with CAD/CAM technology is within an acceptable range to meet clinical requirements. In terms of fracture resistance, Zirconia-based fixed partial dentures (FPDs) have the potential to withstand physiological occlusal forces applied in the posterior region, and therefore provide interesting alternatives to metal-ceramic restorations. Clinical evaluations have indicated an excellent clinical survival of Zirconia-based FPDs and crown restorations. However, some clinical studies have revealed a high incidence of chipping of veneered porcelain. Full-coverage Zirconia-based restorations with adequate retention do not require resin bonding for definitive cementation. Resin bonding, however, may be advantageous in certain clinical situations and is a necessity for bonded restorations, such as resin-bonded FPDs. Combined surface treatment using airborne particle abrasion and specific adhesives with a hydrophobic phosphate monomer are currently reliable for bonding to Zirconia ceramics. Further clinical and in vitro studies are needed to obtain long-term clinical information on Zirconia-based restorations.
Tak W. Chow - One of the best experts on this subject based on the ideXlab platform.
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Effect of Surface Treatment on Shear Bond Strength of Zirconia to Human Dentin
Journal of Prosthodontics, 2011Co-Authors: John Chai, Frederick C.s. Chu, Tak W. ChowAbstract:PURPOSE: The effect of surface treatment using tribochemical silica coating/silane coupling on the shear bond strengths of (1) a glass-infiltrated, Zirconia-reinforced alumina (In-Ceram Zirconia) and (2) a yttria-stabilized Zirconia ceramic (YZ Zirconia) to human dentin was studied.\n\nMATERIALS AND METHODS: Twelve specimens of each ceramic were randomly assigned to one of three surface treatments: (1) no surface treatment (control group); (2) a chairside tribochemical silica coating/silane coupling system (CoJet group); and (3) a laboratory tribochemical silica coating/silane coupling system (Rocatac group). The mode of failure of each specimen was determined under magnification.\n\nRESULTS: The shear bond strengths (mean ± SD) of In-Ceram Zirconia of the control, CoJet and Rocatec groups were 5.7 ± 4.3 MPa, 11.4 ± 5.4 MPa, and 6.5 ± 4.8 MPa, respectively. The corresponding figures for YZ Zirconia were 8.2 ± 5.4 MPa, 9.8 ± 5.4 MPa, and 7.8 ± 4.7 MPa. Two-way ANOVA revealed significant differences in bond strength due to the difference in surface treatment (p= 0.02), but the bond strengths between the two ceramics were not significantly different (p= 0.56). Post hoc tests showed that In-Ceram Zirconia treated with CoJet had significantly higher shear bond strengths than those untreated (p < 0.05) or treated with Rocatec (p < 0.05). Surface treatment did not affect the shear bond strength of YZ Zirconia significantly (p > 0.05).\n\nCONCLUSION: The bonding of In-Ceram Zirconia can be improved by the chairside surface treatment system.
Yu Zhang - One of the best experts on this subject based on the ideXlab platform.
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novel Zirconia materials in dentistry
Journal of Dental Research, 2018Co-Authors: Yu Zhang, Brian R LawnAbstract:Zirconias, the strongest of the dental ceramics, are increasingly being fabricated in monolithic form for a range of clinical applications. Y-TZP (yttria-stabilized tetragonal Zirconia polycrystal) is the most widely used variant. However, current Y-TZP ceramics on the market lack the aesthetics of competitive glass-ceramics and are therefore somewhat restricted in the anterior region. This article reviews the progressive development of currently available and next-generation Zirconias, representing a concerted drive toward greater translucency while preserving adequate strength and toughness. Limitations of efforts directed toward this end are examined, such as reducing the content of light-scattering alumina sintering aid or incorporating a component of optically isotropic cubic phase into the tetragonal structure. The latest fabrication routes based on refined starting powders and dopants, with innovative sintering protocols and associated surface treatments, are described. The need to understand the several, often complex, mechanisms of long-term failure in relation to routine laboratory test data is presented as a vital step in bridging the gaps among material scientist, dental manufacturer, and clinical provider.
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Effects of different sterilization methods on surface characteristics and biofilm formation on Zirconia in vitro
Dental Materials, 2018Co-Authors: Aifang Han, Jukka Pekka Matinlinna, James Kit Hon Tsoi, Yu Zhang, Zhuofan ChenAbstract:Objective: The current laboratory study was to investigate the effect of different sterilization treatments on surface characteristics of Zirconia, and biofilm formation on Zirconia surface after exposure to these sterilization treatments. Methods: Commercially available Zirconia discs (Cerconbase, Degu-Dent, Hanau, Germany) were prepared and polished to the same value of surface roughness. The discs were treated with one of the following sterilization methods steam autoclave sterilization, dry heat sterilization, ultraviolet C (UVC) irradiation, and gamma (γ) ray irradiation. The characteristics of Zirconia surfaces were evaluated by scanning electron microscopy (SEM), surface roughness, surface free energy (SFE), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) measurements. Then, Staphylococcus aureus (S.a.) and Porphyromonas gingivalis (P.g.) bacteria were used and cultured on the respective sterilized Zirconia surfaces. The amount of biofilm formation on Zirconia surface was quantified by colony forming unit (CFU) counts. Results: Significant modifications were detected on the colour and SFE of Zirconia. The colour of Zirconia samples after UVC irradiation became light yellow whilst dark brown colour was observed after gamma ray irradiation. Moreover, UVC and gamma ray irradiation increased the hydrophilicity of Zirconia surface. Overall, dry heat sterilized samples showed the significantly lowest amount of bacteria growth on Zirconia, while UVC and gamma ray irradiation resulted in the highest. Significance: It is evident that various sterilization methods could change the surface which contribute to different biofilm formation and colour on Zirconia.
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on the interfacial fracture resistance of resin bonded Zirconia and glass infiltrated graded Zirconia
Dental Materials, 2015Co-Authors: Herzl Chai, Marina R Kaizer, Asima Chughtai, Hui Tong, Carina Tanaka, Yu ZhangAbstract:Abstract Objective A major limiting factor for the widespread use of Zirconia in prosthetic dentistry is its poor resin-cement bonding capabilities. We show that this deficiency can be overcome by infiltrating the Zirconia cementation surface with glass. Current methods for assessing the fracture resistance of resin-ceramic bonds are marred by uneven stress distribution at the interface, which may result in erroneous interfacial fracture resistance values. We have applied a wedge-loaded double-cantilever-beam testing approach to accurately measure the interfacial fracture resistance of adhesively bonded Zirconia-based restorative materials. Methods The interfacial fracture energy G C was determined for adhesively bonded Zirconia, graded Zirconia and feldspathic ceramic bars. The bonding surfaces were subjected to sandblasting or acid etching treatments. Baseline G C was measured for bonded specimens subjected to 7 days hydration at 37 °C. Long-term G C was determined for specimens exposed to 20,000 thermal cycles between 5 and 55 °C followed by 2-month aging at 37 °C in water. The test data were interpreted with the aid of a 2D finite element fracture analysis. Results The baseline and long-term G C for graded Zirconia was 2–3 and 8 times greater than that for Zirconia, respectively. More significantly, both the baseline and long-term G C of graded Zirconia were similar to those for feldspathic ceramic. Significance The interfacial fracture energy of feldspathic ceramic and graded Zirconia was controlled by the fracture energy of the resin cement while that of Zirconia by the interface. G C for the graded Zirconia was as large as for feldspathic ceramic, making it an attractive material for use in dentistry.
