Abstract:

Cobalt-chromium (Co-Cr) alloys are widely used in PFM restorations due to their favorable mechanical properties and biocompatibility. With the advancement of contemporary manufacturing technologies, new fabrication methods have been introduced, which may influence the structure and hardness of the material.
Aim. The aim of the present study is to compare the Vickers hardness number of a cobalt-chromium alloy produced using three different manufacturing technologies.
Materials and Methods. A total of 15 specimens made of Co-Cr alloy, measuring 8 mm in width and 4 mm in height, were fabricated and divided into three groups (n = 5) according to the manufacturing technique used: casting, 3D printing, and milling. All samples were standardized in terms of shape and size and subjected to identical surface treatment. Vickers hardness testing was performed under standard conditions with a specified load and dwell time. The obtained results were statistically analyzed (IBM SPSS Statistics 26, Excel 2015, and EdrawMax 7).
Results. Statistically significant differences in Vickers hardness values were observed among the studied groups. The highest hardness values were recorded for the printed specimens, followed by those produced by milling, while the lowest values were observed in the cast samples. The observed differences can be explained by variations in microstructure and the specific characteristics of the manufacturing processes.
Conclusion. The manufacturing technology has a significant impact on the Vickers hardness number of cobalt-chromium alloys. Modern digital methods such as milling and 3D printing demonstrate superior mechanical properties compared to conventional casting, which may be of importance for the clinical application of PFM restorations.

Keywords: Co-Cr alloys, Vickers hardness, casting, 3D printing, milling