Applied Sciences  
Adticle  
Comparison of Marginal Integrity and Surface Roughness  
of Selective Laser Melting, CAD-CAM and Digital Light  
Processing Manufactured Co-Cr Alloy Copings  
[PERSON] 1, [PERSON] 2, [PERSON] 2, [PERSON] 2, [PERSON] 1, [PERSON] 1, [PERSON] 1, [PERSON] 1 and [PERSON] 1,*  
Department of Prosthetic Dental Science, College of Dentistry, King Saud University, Riyadh 11545, Saudi Arabia; [EMAIL_ADDRESS] (A.A.); [EMAIL_ADDRESS] (S.A.-S); [EMAIL_ADDRESS] (S.A.); [EMAIL_ADDRESS] (A.A.); [EMAIL_ADDRESS] (F.V). Department of General Delstry, King Saud University, Riyadh 11545, Saudi Arabia; [EMAIL_ADDRESS] (A.M.A. ); [EMAIL_ADDRESS] (M.E. ); [EMAIL_ADDRESS] (M.K.A.) Correspondence: [EMAIL_ADDRESS]; Tel: +966-01347/4444  
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(Ra) also influences the retention of indirect restoration [3]. It has been proposed that different fabrication techniques exhibit different Ra levels for cast indirect restorations. The casting with lost-wax technique (Cast-LWT) is commonly used to fabricate metal copings for PFM crowns [6; 7]. The process involves the carving of inlay wax on a dye that mimics the anatomy and morphology of the lost tooth followed by spruing, investing, burnout, and casting with metal ingots [8]. However, it is time consuming and technique and operator sensitive to achieve a better quality of casting restoration [9]. In order to overcome these shortcomings, alternate contemporary digitally advanced fabrication techniques have been developed. Among various techniques, computer-aided design/manufacturing (CAD-CAM) provides better standardization [10]. This method works on the principle of subtractive manufacturing, involving the milling of a solid metal block in to a desired shape of indirect prosthesis [11]. CAD-CAM offers standard-quality restorations, time efficiency, dimensional accuracy, and reduced risk of health hazards [12; 13]. However, subtractive technique is associated with material wastage along with increased cost and difficult accessibility [14]. Current literature demonstrates conflicting outcomes related to the effect of Ra on the marginal misfit of metal copings fabricated using the subtractive technique [15; 16]. Limitations related to the complexity of design obtained by subtractive technique led to introduction of novel additive fabrication techniques including selective laser melting (SLM), selective laser-sintering (SLS), and digital light processing (DLP) [17]. SLM is also referred to as 3D printing which is based on addition of material layer by layer using high power-density laser to melt and fuse non-precious alloy powders, particularly titanium and cobalt-chromium [18]. It can produce complex restoration designs without wasting a large amount of material. It is also able to produce multiple parts at the same time.