Evaluation of additive manufacturing (AM) techniques for the production of metal–ceramic dental restorations

Two approaches, based on time compression techniques, have recently been introduced for the production of dental restorations: the use of drop-on-demand (DoD) wax patterns for the investment casting of cobalt–chromium (CoCr) alloy and the direct fabrication of metal restorations by means of selective laser sintering additive technique. These two technologies are analysed in this paper from the point of view of the accuracy of the final product that can be achieved. To this aim, the Virtual Model (VM) of a specifically designed artefact for dental applications has been used as a reference model. The restorations were first designed, disregarding the manufacturing process, in order to have a single geometry for the subsequent comparisons and were then produced in dental laboratories on the basis of the given geometry. After fabrication, the restoration surfaces were inspected, by using a coordinate measuring machine (CMM), to obtain information on the achieved accuracy. The results have shown that both processes are able to produce clinically acceptable restorations.