Selective Laser Melting-Sintering Technology: From Dental Co-Cr Alloys to Dental Ceramic Materials

The general term of CAD/CAM technology (i.e., Computer-Aided Design/Compute-Aided Manufacturing) comprises several aspects, such as subtractive manufacturing processes, like milling (soft and hard milling), and additive manufacturing processes, like Selective Laser Melting (SLM), which refers to metallic materials, or Selective Laser Sintering (SLS), which refers to glasses/glass-ceramics/ceramic, or polymeric, or related composite materials produced via powder metallurgy technique. In biomaterials fabrications, the first step in SLM or SLS technology is the digital design of the prosthetic restoration, whereby the patient's individual anatomical and morphological features are precisely described. Afterwards laser-aided melting or sintering is repeated (layer-by-layer) until the complete restoration item is fabricated. A wide range of dental materials can be produced by SLM or SLS technology, e.g., metals and alloys, thermoplastic polymers, glasses/ceramics, waxes, and thermoplastic composites. Thus, it is a promising technology for producing a variety of dental restorations, such as metal-ceramic restorations, all-ceramic restorations, maxillofacial prostheses, functional skeletons, individual scaffolds for tissue engineering, etc. SLM technology is already widely applied for fabricating metal objects for dental (e.g., Co-Cr alloy) and orthopedic prostheses. As a subsequence, in the last decade, researchers' interest has been shifted to SLS of ceramic powders, such as SiO2, Al2O3, SiO2/Al2O3, and ZrO2/Y2O3. This article comprehensively reviews the SLS process and its prospects for producing glasses/glass-ceramic/ceramic materials for biomedical/dental applications. The experimental results clearly show that this very modern additive manufacturing technology does not jeopardize the properties of the ceramic biomaterials' properties.