Comparative study on fracture resistance and post-sintering shrinkage of multiple zirconia blocks produced domestically

Comparative study on fracture resistance and post-sintering shrinkage of multiple zirconia blocks produced domestically Purpose.The purpose of this study was to investigate the fracture resistance and shrinkage rate after sintering according to the type of zirconia block manufactured by a domestic company available in Korea.Materials and methods.A total of three zirconia blocks (Estar-Z HT, Osstem Implant; E, Luxen Enamel, DentalMax; L, Razor W1100, UNC International; R) were compared and evaluated.Group E and L were manufactured using Japanese Tosoh powder, and group R was manufactured using Chinese Sinocera powder.To observe the microstructure of the sintered body, 60 specimens were prepared for each group, and the average grain size, defect density and defect size were measured using a scanning electron microscope.To measure the 4-point bending strength of the sintered body, 35 specimens for each group were manufactured in the form of a bar (3 4 45 mm 3 ) and measured using a universal testing machine.To measure the fracture strengths of single crowns, cantilever bridges, and three-unit bridges, 10 (single crown) and 5 (cantilever bridges, three-unit bridges) specimens were produced for each group and the fracture strengths were measured using a universal testing machine.To measure the shrinkage rate of the sintered body, four rectangular parallelepiped (12 11 10 mm 3 ) specimens were produced for each group, and the shrinkage rate was calculated by measuring with a micrometer before and after sintering.One-way analysis of variance and t-test were performed.Results.As a result of microstructure observation, the grain size, defect density and defect size, were increased in the order of groups L,E and R, while the 4-point bending strength, fracture strength of single crown, cantilever bridge, and 3-unit bridge were decreased in the order of groups E,L and R. The shrinkage rate of the x and y axis was the lowest in group E, and there was no significant difference in the shrinkage rate of the z axis among the three groups.Conclusion.When selecting a zirconia block in clinical practice, the microstructure, fracture strength and the