## Fabricating High-Quality 3D-Printed Alloys for Dental Applications  
[PERSON] 1 (c), [PERSON] 2 and [PERSON] 1,3,* (c)  
1 Institute for Biomaterials Research & Development, Kyungpook National University, 2-188-1 Samduk-dong, Jung-gu, Daegu 700-412, Korea; [EMAIL_ADDRESS]  
2 Center for Research Facilities, Yeungnam University, 214-1 Dae-dong, Gyeongsan 712-749, Korea; [EMAIL_ADDRESS]  
3 Department of Dental Biomaterials, School of Dentistry, Kyungpook National University, 2-188-1 Samduk-dong, Jung-gu, Daegu 700-412, Korea  
* Correspondence: [EMAIL_ADDRESS]; Tel. : +82-53-660-6891  
Academic Editor: [PERSON]  
Received: 26 June 2017; Accepted: 7 July 2017; Published: 10 July 2017  
Featured Application: This article will help to find main points to be considered while applying selective laser melting technology in dentistry. **Abstract:** Metal additive manufacturing (AM), especially selective laser melting (SLM), has been receiving particular attention because metallic functional structures with complicated configurations can be effectively fabricated using the technique. However, there still exist some future challenges for the fabrication of high-quality SLM products for dental applications. First, the surface quality of SLM products should be further improved by standardizing the laser process parameters or by appropriately post-treating the surface. Second, it should be guaranteed that dental SLM restorations have good dimensional accuracy and, in particular, a good marginal fit. Third, a definitive standard regarding building and scanning strategies, which affect the anisotropy, should be established to optimize the mechanical properties and fatigue resistance of SLM dental structures. Fourth, the SLM substructure's bonding and support to veneering ceramic should be further studied to facilitate the use of esthetic dental restorations. Finally, the biocompatibility of SLM dental alloys should be carefully examined and improved to minimize the potential release of toxic metal ions from the alloys. Future research of SLM should focus on solving the above challenges, as well as on fabricating dental structures with \"controlled\" porosity. **Keywords:** additive manufacturing; anisotropy; dental alloy; selective laser melting  
Additive manufacturing (AM), also known as three-dimensional (3D) printing or rapid prototyping, is the process of joining materials to make 3D objects from digital data, usually layer upon layer [1, 2]. Metal AM, especially selective laser melting (SLM), has been receiving particular attention because metallic functional structures with complicated configurations in various industrial, medical, and dental sectors can now be fabricated using this technique [1, 2, 3]. However, due to the complex nature of metal AM, there still exist many challenges for the successful fabrication of high-quality metallic products with favorable microstructures and properties [3]. In particular, several challenges need to be solved in order to apply the SLM technology widely in dental applications, replacing conventional techniques such as casting [1]. It has been known that the SLM technique can produce 3D objects with minimal pre-processing and/or post-processing requirements [3]. In reality, however, the supporting structure created in the manufacturing stage must be manually removed after the final 3D product is completed [2, 4]. In addition, low surface quality (such as cracking, delamination, and swelling) is one of the major drawbacks encountered in the SLM process [5]. [PERSON] et al. [6] demonstrated that three laser process parameters (laser power, scan rate, and scan-line spacing) directly influenced the surface roughness of an SLM cobalt-chromium (Co-Cr) dental alloy. [PERSON] et al. [5] suggested \"laser re-melting,\" in which, after scanning a layer and melting the powder, the same slice is re-scanned before adding a new layer. Laser re-melting can also be applied to only the last layer of the SLM part to enhance the surface quality [5].