Thermal gradients and residual stresses in veneered Y-TZP frameworks

Tholey, M.J.; Swain, Michael V.; Thiel, Norbert

doi:10.1016/j.dental.2011.08.001

Cited by 132 publications

(89 citation statements)

References 11 publications

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“…Similar patterns in fractured zirconia-based prostheses, in which the crack plane never reaches the interface, have also been described clinically (Sailer et al, 2007b) and in in vitro fatigue experiments (Coelho et al, 2009;Rosentritt et al, 2009). Since the cooling-rate influence has been shown to be small, the stress near the interface as a result of CTE mismatch is expected to be tensile, due to radial and hoop stress components (Tholey et al, 2011), explaining the decreased lifetime for the high-mismatch veneer/core combination.…”

Section: Discussionmentioning

confidence: 60%

A Photoelastic Assessment of Residual Stresses in Zirconia-Veneer Crowns

et al. 2012

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Residual stresses within the veneer are linked to the high prevalence of veneer chipping observed in clinical trials of zirconia prostheses. We hypothesized that the thermal mismatch between the zirconia infrastructure and the veneer porcelain, as well as the rate used for cooling zirconia-veneer crowns, would be directly proportional to the magnitude of residual stresses built within the veneer layer. Two porcelains with different coefficients of thermal expansion were used to veneer zirconia copings, to create high or low thermal mismatches. The crowns were cooled according to a fast-or a slowcooling protocol. The retardation of polarized light waves was used to calculate the residual stress magnitude and distribution across the veneer, according to the photoelasticity principle, in 1.0-mm-thick crown sections. While thermal mismatch was an important factor influencing the maximum stress development in the veneer, cooling rate had a minor role. Curved surfaces were preferential sites for stress concentration regardless of thermal mismatch or cooling rate.

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Section: Discussionmentioning

confidence: 60%

A Photoelastic Assessment of Residual Stresses in Zirconia-Veneer Crowns

et al. 2012

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“…For this temperature region, various studies have demonstrated significant changes in the thermal expansion properties which strongly affect thermal stress distribution 30,31) . However, the CTE values given by the manufacturer for the ceramic materials, and which has also been used for calculation of thermal residual stresses in the present and previous studies 14,32,33) , only applies to the temperature range below the glass transition temperature (20-500°C).…”

Section: Discussionmentioning

confidence: 99%

Interfacial adhesion of zirconia/veneer bilayers with different thermal characteristics

et al. 2014

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The aim of this study was to investigate how changes in the thermal characteristics of veneer ceramics with almost identical chemical and mechanical properties but with different coefficients of thermal expansion (CTE) can modify their interfacial adhesion to zirconia. 48 bilayers made of one Y-TZP ceramic and four veneer ceramics were fabricated (n=12). Thermal residual stresses were calculated on the basis of the CTE and glass transition temperatures. After defined notching all specimens were loaded in a four-point bending test and the critical loads were recorded which induced stable crack extension at the adhesion interface. The strain energy release rate (G, J/m 2 ) was calculated and was taken as a measure of interfacial adhesion. The CTE of the veneer ceramics were significantly correlated with their adhesion to Y-TZP (p<0.001). Interfacial adhesion in zirconia/veneer bilayers is predominantly affected by the thermal characteristics of the veneer ceramic.

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“…Because of the high stiffness of ceramics materials, residual stresses are produced and it can increase the probability of porcelain veneer chipping during mastication 18,19 . Moreover, considering that zirconia-based substructures have lower thermal diffusivity and thermal conductivity if compared to metallic substructures for metal-ceramic restorations, several firing cycles with different cooling methods have been proposed, which vary antagonistically since slow cooling 7,11,14,20,21 to fast cooling 6,9,10,12,[20][21][22][23] . However, there is no consensus about an ideal firing cycle.…”

Section: Introductionmentioning

confidence: 99%

“…In the present study, the cooling method did not influence the flexural strength results, which points out the role of the thermal proprieties of the framework in a bilayer complex. In a bilayer porcelain/zirconia, the compressive/ tempering stresses in the porcelain layer under fast cooling can improve the resistance of the surface layer 7 and develop high residual tension at the zirconia/porcelain interface 6,9 . Thus, this phenomenon has great importance to bilayers.…”

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confidence: 99%

Effect of the Cooling Rate on the Properties of Veneer Porcelain for Zirconia Dental Prosthesis

et al. 2017

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To solve chipping of veneer porcelain in zirconia dental prosthesis it has been studied different cooling rates in firing schedules to control residual stresses generated by differences in thermal properties between the ceramics. However, cooling rates may affect the porcelain, irrespectively of interaction with zirconia. This study analyzed the effect of cooling rate on the three-point flexural strength (FS), residual stress, Vickers hardness (VH) and V-notch fracture toughness (SEVNB) on a feldspathic porcelain (Vita VM9) indicated for covering zirconia. Bar-shaped specimens were sintered according manufacturer's schedule firing and cooled at different rates (slow, normal or fast). Specimens were tested for FS (n=30), VH (n=15) and SEVNB tests (n=15). Weibull analysis were performed from FS values to measure reliability and probability of failure (PF). One-way ANOVA was significant for VH (p<0.001), and Tukey's test showed that slow cooling led to higher values. There was no significant difference for FS (p=0.654) and SEVNB (p=0.734). Fast cooling led to the lowest PF, but cooling rate factor was not significant for Weibull modulus. All cooling group showed residual tensile stress (MPa): Slow = 34.81; Normal = 27.04; Fast = 18,98. It was concluded that cooling rate produce minor changes in the porcelain properties.

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Thermal gradients and residual stresses in veneered Y-TZP frameworks

Cited by 132 publications

References 11 publications

A Photoelastic Assessment of Residual Stresses in Zirconia-Veneer Crowns

A Photoelastic Assessment of Residual Stresses in Zirconia-Veneer Crowns

Interfacial adhesion of zirconia/veneer bilayers with different thermal characteristics

Effect of the Cooling Rate on the Properties of Veneer Porcelain for Zirconia Dental Prosthesis

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