Zirconium dioxide is a material that has been known since the 1960s. Its first application took place in devices used by NASA. Zirconium dioxide is used in the production of all-ceramic and hybrid bearings. Since the 1990s, it has been the most popular application in dentistry, where it is used for crowns, arches and all-ceramic bridges. It is characterized by biocompatibility, translucency and high mechanical strength. Zirconium dioxide is supplied in round blocks with dimensions of 180 × 30 mm, its properties are similar to gypsum. Full mechanical properties are obtained during sintering - baking in the oven at the temperature of 1400 degrees Celsius for 8 hours. During this process, a shrinkage occurs, which is approximately 20%. The article presents three materials from zirconium dioxide from different manufacturers, and the original treatment of zirconium dioxide was presented. Each of the processed materials has been divided into three groups. Each group for a given material was sintered in a different way. The 3-point bending strength tests were carried out using the proprietary holder on the Instron 8874 servo-hydraulic testing machine. The results of the tests were presented on the charts and summarized by the discussion.