Residual stresses in bilayer dental ceramics

Taskonak, Burak; Mecholsky, John J.; Anusavice, Kenneth J.

doi:10.1016/j.biomaterials.2004.08.025

Cited by 114 publications

(92 citation statements)

References 12 publications

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“…When porcelain is fused to the bulk substructure material attention must be paid to the matching of the CTE values. A large mismatch between the porcelain veneer and core materials can cause residual stresses and result in chipping of the veneer [31,32]. In our study, no large chippings but delamination of the wash or glaze coating were seen after mechanical testing in Scanning Electron Microscope.…”

Section: Discussionmentioning

confidence: 42%

The Effect of Heat Treatment and Feldspathic Glazing on Some Mechanical Properties of Zirconia

Hjerppe

Fröberg

Lassila

et al. 2010

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Purpose In dental practice, zirconia substructures for crowns and fixed partial dentures are veneered with feldspathic porcelain for better aesthetical properties. The purpose of this study was to evaluate the effect of heat treatment during the veneering process on the mechanical properties of zirconia. Methods 105 zirconia (ICE Zirkon, Zirkonzahn, Italy) disc shaped specimens were divided into seven groups (n=15/ group) and sintered at 1500°C. Control specimens (group 1) were left as such. Specimens in the study groups were: 2) one heat treatment in a porcelain firing furnace; 3) a heat treatment with two firing cycles; 4) one heat treatment with a thin coating of feldspathic glazing on the tension side; 5) two heat treatments with a thin coating of feldspathic wash and glazing on the tension side; 6) one heat treatment with a thin coating of feldspathic glazing on the compression side; 7) two heat treatments with a thin coating of feldspathic wash and glazing on the compression side. Biaxial flexural strength and surface microhardness of the specimens (diameter 19 mm, thickness 1.2 mm) were measured. The effect of heat treatment and feldspathic glazing on the phase transformations of zirconia was determined by XRD-analysis. The data were calculated using ANOVA-analysis.Results Repeated heat treatment did not influence the mechanical properties of zirconia (p>0.05). No difference (p>0.05) was found in terms of the surface microhardness between the groups. Some transformation from the tetragonal to the monoclinic phase was seen on the surface of the specimens after heat treatment and feldspathic glazing coating. Conclusions Repeated heat treatment does not affect the strength of zirconia milled in the green-stage form.

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Section: Discussionmentioning

confidence: 42%

The Effect of Heat Treatment and Feldspathic Glazing on Some Mechanical Properties of Zirconia

Hjerppe

Fröberg

Lassila

et al. 2010

Silicon

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“…Residual stresses generated due to differential cooling should not be neglected. The mismatch of CTE between the framework and the veneer ceramic yields to increased interfacial failures as a result of increased tensile stresses at the interface and compressive stresses within the veneer ceramic [32]. It has been also reported that the mismatch of CTE causes high tensile pre-stress at the frameworkveneer interface [6,43].…”

Section: Sbs Tests Provide Valuable Information About the Materials Tmentioning

confidence: 99%

A study of compressive strength between zirconia framework and veneering ceramic as a function of thermal expansion coefficient using Shell–Nielsen test method

Gökçe

Çötert

Özcan

2015

Journal of Adhesion Science and Technology

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This study investigated the bond strength between a zirconia framework and four veneering ceramic materials with varying coefficients of thermal expansions (CTE) using the Shell Nielsen bond strength test. Zirconia rods (N=40) (ICE Zirkon) (diameter: 4 mm, height: 20 mm) were milled in green state and sintered. After firing, the zirconia rods were air-abraded, ultrasonically and steam cleaned. They were randomly assigned to receive four veneering ceramic materials (n=10/group), namely a) Vita VM9 (VZ; 9-9.2x10 -6 K -1 ), b) Cerabien ZR (CZ; 9.1x10 -6 K -1 ), c) Matchmaker ZR (MM; 9.4x10 -6 K -1 ) and d) IceZirconia Ceramic (IZ; 9.6x10 -6 K -1 ). The veneering ceramics were then fired onto zirconia discs (height: 2 mm, thickness: 2 mm) circumferentially and were thermocycled for 6.000 times (5/55 0 C, dwell time: 30 s).Specimens were loaded from the top of the zirconia rods (crosshead speed: 0.5 mm/min) in a universal failure type between the framework and veneering ceramic followed by mixed failures. Veneering ceramics with a greater mismatch of CTE with the zirconia framework exhibited similar Shell Nielsen bond strength to those with fewer mismatches. Shell Nielsen bond strength test used in this study subjecting the zirconia framework-veneering ceramic assemblies to circumferential shear forces did not show the effect of CTE mismatch between the veneering ceramics accept those between CZ (9.1x10 -6 K -1 ) and IZ (9.6x10 -6 K -1 ).

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“…Such residual stresses may arise from the thermal expansion mismatch between the porcelain veneer and the zirconia framework as well as from the rapid cooling after sintering, owing to the low thermal diffusivity of zirconia. In an attempt to estimate the magnitude of residual stresses, theoretical [15] and experimental [16][17][18][19] work have been conducted on flat models of PFZ bilayer systems. However, dental crowns and bridges have complex geometries with varying thickness of veneer and core.…”

Section: Introductionmentioning

confidence: 99%

“…The Vickers indentation method (VIM) was first used to determine surface residual stresses in brittle materials by Marshall and Lawn 35 years ago [20]. In this method, surface residual stresses can be estimated by comparing the indentation crack length in stressed samples to that in unstressed samples [17,18,[24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

“…The disadvantage of the VIM is, as with many other mechanical testing methods such as hole-drilling, the requirement of a relatively smooth surface to assure an accurate measurement of indentation crack length. The VIM has been used to estimate the residual stresses in bilayer dental ceramics [17,18]. However, all previous studies have used flat models of bilayer systems.…”

Section: Introductionmentioning

confidence: 99%

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Residual stresses in porcelain-veneered zirconia prostheses

2012

The Journal of Prosthetic Dentistry

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Objectives-Compressive stress has been intentionally introduced into the overlay porcelain of zirconia-ceramic prostheses to prevent veneer fracture. However, recent theoretical analysis has predicted that the residual stresses in the porcelain may be also tensile in nature. This study aims to determine the type and magnitude of the residual stresses in the porcelain veneers of fullcontour fixed-dental prostheses (FDPs) with an anatomic zirconia coping design and in control porcelain with the zirconia removed using a well-established Vickers indentation method.Methods-Six 3-unit zirconia FDPs were manufactured (NobelBiocare, Gothenburg, Sweden). Porcelain was hand-veneered using a slow cooling rate. Each FDP was sectioned parallel to the occlusal plane for Vickers indentations (n = 143; load = 9.8 N; dwell time = 5 s). Tests were performed in the veneer of porcelain-zirconia specimens (bilayers, n = 4) and porcelain specimens without zirconia cores (monolayers, n = 2).Results-The average crack lengths and standard deviation, in the transverse and radial directions (i.e. parallel and perpendicular to the veneer/core interface, respectively), were 67 ± 12 μm and 52 ± 8 μm for the bilayers and 64 ± 8 μm and 64 ± 7 μm for the monolayers. These results indicated a major hoop compressive stress (~40 to 50 MPa) and a moderate radial tensile stress (~10 MPa) in the bulk of the porcelain veneer.Significance-Vickers indentation is a powerful method to determine the residual stresses in veneered zirconia systems. Our findings revealed the presence of a radial tensile stress in the overlay porcelain, which may contributed to the large clinical chip fractures observed in these prostheses.

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Residual stresses in bilayer dental ceramics

Cited by 114 publications

References 12 publications

The Effect of Heat Treatment and Feldspathic Glazing on Some Mechanical Properties of Zirconia

The Effect of Heat Treatment and Feldspathic Glazing on Some Mechanical Properties of Zirconia

A study of compressive strength between zirconia framework and veneering ceramic as a function of thermal expansion coefficient using Shell–Nielsen test method

Residual stresses in porcelain-veneered zirconia prostheses

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