Additive manufacturing technologies for processing zirconia in dental applications

OBJECTIVE: The objective of this narrative review was to summarize the current status and future perspectives of additive manufacturing (AM) technologies with a particular emphasis on manufacturing zirconia-based materials. AM technologies include vat photopolymerization, material jetting, material extrusion, selective laser sintering (SLS), and selective laser melting (SLM) technologies based on either powder bed fusion (PBF) technologies or direct energy deposition, or sheet lamination based on binder jetting technologies. MATERIALS AND METHODS: A comprehensive literature review was performed, specifically evaluating AM technologies assigned for processing zirconia. An electronic database search was performed using keywords and MeSH terms. The search was confined to full-text articles written in English and published in peer-reviewed journals between 1999 and 2018. RESULTS: A total of 62 articles were included in this review, of which 56 described the AM processes and 6 reported on AM applications in the field of dentistry. A broad diversity of literature exists regarding AM technologies for ceramic materials, which complicates the establishment of a classification system for the current AM technologies for zirconia. The variations in the composition of zirconia slurries or mixtures across different technologies often made it difficult to identify the proper nature of such information. Mechanical properties of printed zirconia materials utilizing different technologies were investigated through a wide range of tests. Overall, the review indicates that manufacturing zirconia using AM technologies could be achieved without issues, but mechanical properties appear to be poor compared with conventional manufacturing procedures. CONCLUSIONS: The results of this review indicate the necessity for further potential improvement in AM technologies for manufacturing zirconia reconstructions along with advances in material composition before zirconia could be considered as a material for standard care.