Thermal-induced residual stresses affect the lifetime of zirconia–veneer crowns

Influence of thermal expansion mismatch on residual stress profile in veneering ceramic layered on zirconia: Measurement by hole-drilling

“…Results of the present study support the development of veneering ceramics with a CTE inferior but close to the Y-TZP CTE (+0.2 ppm/ • C ˛). They are confirmed by Belli et al who tested zirconia-based crown resistance to cyclic fatigue and recommended a +0.3 ppm/ • C ˛ [37], by Aboushelib et al who performed disc biaxial flexure tests and showed that nul ˛ promotes failure resistance, and also by Hallman et al who recommended veneer ceramic with a coefficient of thermal expansion closely matching that of zirconia to suppress the t-m phase transformation at the veneer-zirconia interface and improve the mechanical properties [36].…”

Characterization of residual stresses in zirconia veneered bilayers assessed via sharp and blunt indentation

“…In low CTE mismatch combinations, in contrast, crack propagation has shown not to be influenced by residual stresses, running in a straight path through the veneer [7], just as observed for the LAVA group in this study. Crack propagation behaviors due to differences in stress gradients reflect therefore on the lifetime of veneer-ZrO 2 dental prostheses, such that higher CTE mismatches may significantly reduce the time for chipping [53].…”

Effect of repeated firings on flexural strength of veneered zirconia

“…For this reason, to obtain an appropriate esthetics, once the zirconia framework is machined the feldspathic ceramic has to be layered with a traditional veneering technique. However, chipping and delamination of the veneering ceramic have been reported to occur in a higher rate than PFM [17][18][19][20][21][22][23][24].…”

“…To reduce the residual thermal stresses the use a veneering ceramic with a CTE as close as possible to that of the framework has been advised. This aspect has been investigated for zirconia/ceramic restorations as well [20,[49][50][51][52][53] and it has been reported that the processes of slow heating and slow cooling increase chipping resistance [20][21][22][23]. The possible effect of multiple firings has also been investigated.…”