The effect of melt infiltration of borosilicate glass on biaxial flexural strength of porcelain-veneered zirconia

To evaluate the effect of melt infiltration on the biaxial flexural strength of porcelain-bonded zirconia, borosilicate glasses were used in this study. Presintered yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) blocks were milled and used for disc specimens. Prior to veneering of porcelain, the infiltration of borosilicate glass on zirconia was performed at 1,100 °C for 1 h. After a biaxial flexural test with the crosshead speed of 0.1 mm/min, fractured surfaces and interfaces between zirconia and veneer porcelain were observed with a Scanning Electron Microscope (SEM). The fracture strength of sintered zirconia and veneer porcelain was significantly increased by the melt infiltration of borosilicate glass (P < 0.05). The melt infiltration process of borosilicate glass greatly improved the Weibull modulus of sintered zirconia. However, the Weibull modulus of porcelain increased slightly. The sintered zirconia group showed a smooth fracture surface containing many pores, but the glass-infiltrated zirconia group showed a rough fracture surface.