Comparison of the mechanical properties and microstructures of fractured surface for Co-Cr alloy fabricated by conventional cast, 3-D printing laser-sintered and CAD/CAM milled techniques

Cobalt-Chromium (Co-Cr) alloys have been widely used in dentistry for removable partial dentures, metal frames, and porcelain-fused-to-metal crowns. Because the alloys are strong, resistant to corrosion and relatively inexpensive compared to gold alloys and some all-ceramic materials. However, the fabrication processes for the alloys, such as casting, cutting and plastic works, are usually difficult because of their high melting point (1349-1449°C), hardness, and limited ductility. Casting has been the most common method to fabricate dental alloy for many decades, but errors accumulated in the series of laboratory steps are inevitable. Simplification of procedure can reduce these errors along with costs that are related to expensive devices. CAD/CAM technique was also introduced in dentistry more than 20 years ago. One major advantage of using milling technology is that some disadvantages of casting, such as several clinical appointments needed including impression taking procedure, casting-induced flaws and porosities which can degrade the quality of the reconstructions, can be avoided. Therefore, it can be both time-saving and cost-effective compared to conventional casting technology. Comparison of the mechanical properties and microstructures of fractured surface for