Mechanical Properties and Metal-Ceramic Bond Strength of Co-Cr Alloy Manufactured by Selective Laser Melting.

Joon-Ki Hong,Seong-Kyun Kim,Jai-Young Koak,Seong-Joo Heo

doi:10.3390/ma13245745

Joon-Ki Hong, Seong-Kyun Kim + Show 2 more

Open Access

https://doi.org/10.3390/ma13245745

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Journal: Materials	Publication Date: Dec 16, 2020
Citations: 23	License type: CC BY 4.0

Affiliation: Seoul National University Dental Hospital

Abstract

Cobalt–chromium (Co-Cr) metal is one of the widely used biomaterials in the fabrication of dental prosthesis. The purpose of this study was to investigate whether there are differences in the properties of metals and bond strength with ceramics depending on the manufacturing methods of Co-Cr alloy. Co-Cr alloy specimens were prepared in three different ways: casting, milling, and selective laser melting (SLM). The mechanical properties (elastic modulus, yield strength, and flexural strength) of the alloys were investigated by flexure method in three-point bending mode, and microstructures of the specimens were analyzed. After application of the veneering ceramic through the three-point bending test, bond strength of the Metal-Ceramic was investigated. The cracked surfaces were observed by means of energy dispersive X-ray (EDX) spectroscopy and scanning electron microscopy (SEM) with backscattered electron (BSE) images. In mechanical properties, the elastic modulus was highest for the casting group, and the yield strength and flexural strength were lowest for the milling group. The SLM group showed finer homogeneous crystalline-microstructure, and a layered structure was observed at the fractured surface. After the ceramic bond strength test, all groups showed a mixed failure pattern. The casting group showed the highest bond strengths, whereas there was no significant difference between the other two groups. However, all groups have met the standard of bond strength according to international standards organization (ISO) with the appropriate passing rate. The results of this study indicate that the SLM manufacturing method may have the potential to replace traditional techniques for fabricating dental prosthesis.

Highlights

With the development of computer-aided design/computer-aided manufacturing (CAD/CAM)technology, CAD/CAM prostheses are often used these days in dentistry [1]
The elastic modulus was higher for the casting group (Figure 5A; p < 0.05)
Differences in the yield and flexural strengths between the casting and selective laser melting (SLM) groups were not statistically significant, but these strengths were significantly lower for the milling group (Figure 5B,C; p < 0.05)

Summary

Introduction

With the development of computer-aided design/computer-aided manufacturing (CAD/CAM). Technology, CAD/CAM prostheses are often used these days in dentistry [1]. Metal-Ceramic prostheses made of cobalt–chrome (Co-Cr) alloys have been used extensively [2]. The casting method, most commonly used when producing Co-Cr frameworks, is applied by producing and casting a wax pattern. This conventional method is labor-intensive, can cause errors in the manufacturing process, and is prone to human mistake [4]. Recent developments in CAD/CAM technology have made it possible to create Co-Cr frameworks by means of nontraditional methods [5]

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