COMPARATIVE STUDY OF THE MICROHARDNESS OF RUSSIAN AND FOREIGN CAD/CAM COMPOSITE BLOCKS FOR THE MANUFACTURE OF CROWNS

This study provides a comparative analysis of the microhardness of three composite CAD/CAM blocks widely used in modern orthopaedic dentistry for the fabrication of permanent crowns. The Russian material Nolatek, along with two foreign analogues—Tetric CAD and a composite block manufactured by 3M ESPE—were selected as the objects of study. The relevance of this study stems from the need for an objective and evidence-based assessment of the mechanical properties of composite materials used in digital prosthetics and modern restorative technologies. Microhardness is considered one of the most informative parameters reflecting a material's resistance to localized mechanical loads, surface deformation, abrasive wear, and damage during clinical use. Microhardness was determined using the Vickers method on pre-standardized samples, ensuring high reproducibility of the obtained data and the validity of intergroup statistical comparisons. The study found that all analyzed materials exhibit a similar range of microhardness values, although Tetric CAD is characterized by moderately higher values. The Russian Nolatek composite demonstrated microhardness comparable to foreign models, demonstrating its high technological level and clinical competitiveness. The obtained results confirm that the studied CAD/CAM blocks possess sufficient resistance to mechanical stress and can be recommended for use in digital orthopaedic protocols. However, it should be noted that, in addition to microhardness, other physical and mechanical parameters of materials, including flexural strength, elastic modulus, and other parameters under long-term functional loading, significantly influence the success of orthopaedic treatment. A comprehensive assessment of these characteristics allows for a more objective prediction of the clinical performance of restorations, optimizes material selection, and increases the durability of orthopaedic structures in digital dentistry. This also substantiates the need for further experimental and clinical studies aimed at an in-depth study of composite CAD/CAM materials.