The use of slow heating and slow cooling regimens to strengthen porcelain fused to zirconia

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

“…It is known that residual stresses can occur due to a thermal mismatch between the zirconia core and the porcelain veneer, or due to an inadequate cooling rate after the last firing of the porcelain veneer applied on zirconia 11,12,17,23 . However, considering solely porcelain, stresses may also be generated due to a non-uniform solidification resultant from thermal gradients from the surface to the center of the porcelain 7,12 , once the ceramic materials have low thermal diffusivity and low thermal conductivity.…”

“…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.…”

Efecto del liner en la resistencia adhesiva de cerámica feldespática a la zirconia utilizando protocolo de enfriamiento lento

“…17,18 The present study evaluated and compared a ceramic veneer bond strength to zirconia blocks by different manufacturers (Ecco Amann Girrbach Zirconia -Ivoclar e.max ZirCAD) and the convenience of using a liner through a slow cooling protocol as suggested by some authors. 8,9,[19][20][21] The use of liners has been proposed to improve the aesthetic characteristics of restorations with zirconia structures. 11 However, some authors suggest that using a liner can affect the bond strength of the ceramic veneer to zirconia.…”

“…8,9,[19][20][21] El manejo de estos protocolos disminuyen significativamente la tensión residual que se genera en la cerámica de recubrimiento con estructuras en zirconia. 24,25 Algunos autores sugieren que una tensión residual excesiva en la cerámica de recubrimiento sometida a cargas oclusales podría ser uno de los factores que propician la aparición de chipping o delaminación de la cerámica de recubrimiento con estructuras a base de zirconia.…”

“…8,9,[19][20][21] La utilización del liner se ha propuesto para mejorar las características estéticas de las restauraciones con estructuras en zirconia. 11 Sin embargo, algunos autores sugieren que al utilizar un liner se puede afectar la resistencia adhesiva de la cerámica de recubrimiento a la zirconia.…”