Introduction: The occurrence of cracks and stratifications is the most common cause of the failure of zirconium-dioxide restorations, where the rate of cracks is significantly more frequent than compared to metallic porcelain restorations. It has been proven that cracks are formed due to number of factors. This may be due to inadequate adhesion between the ZrO2 framework and the layer of porcelain mass, forces generated by the coefficients of the thermal expansion of two materials, shrinkage of ceramics in sintering, difference in thickness between the core and the coating of the material in the inadequate design of the structure. Purpose: The purpose and scope of this diploma work is to present the influence of various methods of surface treatment of zirconium dioxide on the strength of the bond with the porcelain mass. We will test, analyze and present the analysis of the sample. The binding strength will be determined by a shear test. Methods: We used in this work the descriptive and analytical methods. The diploma work is based on a review of professional literature. Practical work and preparation of samples were done in dental laboratories in Rijeka. The test was done at the Institute of Technology Materials at the Faculty of Mechanical Engineering in Maribor. Results: In the case of a shear test, there was a connection between zirconium dioxide and porcelain. The device for carrying out mechanical tests the Zwick Roell Z010 produced a F- Δl diagram to determine the force by which the test pieces were broken. Based on experimentally obtained values of breaking forces, we determined the shear strength of the test pieces depending on the composition and surface treatment of the zirconium dioxide frame. Discussion and conclusion: The results of the experiment to determine the binding strength between the zirconium dioxide and porcelain were expected. They also comply with the manufacturer's instructions. Understanding the combination of functionality, aesthetics and durability of materials is a key to a good product. For the sake of ensuring all three elements, we need a material that meets all the requirements. Zirconium dioxide is one of such materials, however, it is still the subject of researches and, despite of its disadvantages, has excellent preconditions.
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