Objectives: The aim of this in vitro study was to investigate the influence of speed sintering protocol on the fracture resistance of the translucent zirconia.
Materials and Methods:Forty intact maxillary premolars were used in this study. All teeth were divided according to the type of zirconia into two main groups (n=20): Group K receiving KATANA HTML zirconia and Group Z receiving Zolid fx ML zirconia, Then, each group subdivided according to sintering protocol into two subgroups (n=10): KC and KS refer to KATANA HTML sintered by conventional and speed sintering protocols, respectively, while ZC and ZS refer to Zolid fx ML sintered by conventional and speed sintering protocols, respectively. The teeth were prepared by the aid of dental surveyor. After cementation with self-adhesive resin, the specimens were subjected to thermal cycling for 5000 cycles and mechanically loaded for 120,000 cycles.Then, the specimens were loaded to fracture. Mode of failure was assisted using stereoscopy and scanning electron microscope micrographs.
Results: The highest mean value of fracture resistance was recorded in KC subgroup (3083.79 ±844.88) followed byKS subgroup (2864.41 ±692.15)vs ZC (2342.85 ±434.04) and ZS (1829.18 ±299.38) subgroups. Two-way ANOVA showed no interactions between variables (P=.448).
Conclusions:Increasing the yttria content had negative impact on zirconia fracture resistance. Although, the sintering protocols did not influence the fracture resistance of the tested zirconia, Zolid fx ML was affected by the speed sintering protocol. Despite of the present results, the tested zirconia can be used safely at premolar area.