Discrepancy of complete-arch titanium frameworks manufactured using selective laser melting and electron beam melting additive manufacturing technologies

STATEMENT OF PROBLEM: Titanium frameworks for implant-supported prostheses can be additively manufactured using different powder-based fusion technologies, including selective laser melting (SLM) and electron beam melting (EBM). Some manufacturers have developed a technique that combines the printing of the framework with the subsequent machining of the implant interface. Whether these technologies produce frameworks with acceptable accuracies is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the discrepancy obtained from the digitizing procedures of the definitive cast, the implant-prosthesis discrepancy, and the distortion of the manufacturing processes in the fabrication of titanium frameworks for implant-supported complete-arch prostheses manufactured using SLM and EBM additive manufacturing technologies. MATERIAL AND METHODS: three times by best-fit superimposure of the definitive cast STL file, the definitive cast titanium framework, and the framework STL file by using a coordinate measuring machine (CMM) controlled by software (Geomagic). The Kruskal-Wallis and Mann-Whitney U statistical tests were used (α=.05). RESULTS: The digitizing procedures of the definitive cast showed a mean accuracy of 3 ±3 μm. Except for the z-axis (P<.05), no significant differences were observed between the SLM and EBM technologies for implant prosthesis discrepancy for the x- or y-axis (P>.05). The most favorable results were obtained in the z-axis, representing the occlusogingival direction. Three-dimensional discrepancy measurements in all comparisons ranged between (60 ±18 μm and 69 ±30 μm) and were not statistically significant (P>.05). The highest discrepancy was observed in the y-axis (37 to 56 μm), followed by the x- (16 to 44 μm) and z- (6 to 11 μm) axes (P<.05). CONCLUSIONS: The titanium frameworks analyzed for a complete-arch implant-supported prosthesis fabricated using either the SLM or EBM additive technologies showed a clinically acceptable implant-prosthesis discrepancy, where similar discrepancies on the x-, y-, and z-axes were found between the additive manufacturing technologies. Both technologies showed comparable abilities to manufacture the STL file additively on the x-, y-, and z-axes.