comparison between biaxial flexural strength and microstructure of polished and glaze-fired specimens of zirconia lithium silicate glass ceramic

Introduction: there has been a growing interest in glass ceramic systems with good esthetics, high fracture resistance, bonding durability, and simplified fabrication techniques using cad/cam. the aim of this study was to compare flexural strength in polished and glazed and fired specimens of zirconium lithium silicate (zls) cad/cam blocks celtra duo. methods: a total of 14 specimens of celtra duo (dentsply sirona, germany) were designated and equally divided into two groups, including group i (n=7; as polished) and group ii (n=7; as glazed and fired) according to the manufacturers’ instructions. then biaxial flexural strength was tested according to iso 6872 using a universal testing machine and piston-on-three-ball method after polishing, glazing, and firing. the fractured surfaces and microstructure were observed by scanning electron microscope (jeol/gsm5300). data were then statistically analyzed using spss software (version 20.0). results: there were statistically significant differences in biaxial flexural strength between a polished and glaze-fired specimen of zls glass ceramic discs as biaxial flexural strength was lower in polished specimens (mean±standard deviation: 158.7±21.67 mpa), while the glazed specimens showed higher biaxial flexural strength (mean±standard deviation: 261.5±31.89 mpa). conclusion: glazing and firing of celtra duo specimens increased biaxial flexural strength significantly in comparison to polishing with no significant change in the microstructure.