Discrepancy of Titanium Frameworks Manufactured Using Additive Manufacturing Technologies

Objectives: To evaluate the discrepancy between plaster cast and titanium framework for implant-borne complete arch prosthesis manufactured using selective laser melting (SLM) and electron beam melting (EBM) additive manufacturing technologies.
Methods: A complete edentulous mandibular definitive cast with 4 implant analogs and duplicate of the screw-retained provisional restoration of a patient was obtained. The STL file of the framework design was prepared using dental software (Exocad). Six frameworks were manufactured using either SLM (3D Systems, Belgium) or EBM (Arcam, Sweden) technologies. Discrepancy (μm) was measured at x (mesiodistal), y (buccolingual), z (occluso-gingival) axis using the formula (3D=Sqx²+y²+z²) three times by best-fit superimposure of a) cast model-STL file, b) cast-titanium framework, c) framework-STL file using coordinate measuring machine (CMM) operated with a software (Geomatic). Data were analyzed using Kruskal Wallis, Mann-Whitney U and Bonferroni tests (alpha=0.05).
Results: No significant difference was observed between SLM and EBM technologies for cast model-STL file, cast-titanium framework and framework-STL file discrepancies in 3D gap within each x,y,z axis (p>0.05). 3D gap measurements in all comparisons ranged between (60.2±18.5 and 68.6±29.7). The highest discrepancy was observed in the y- (36.9-56.2), followed by x- (16.4-44.7) and z- (6.2-10.8) axis (p<0.05).
Conclusions: Titanium frameworks for complete arch implant-borne prosthesis fabricated using either SLM or EBM additive technologies showed similar discrepancies between the cast, STL files and the framework with more favourable results in the z-axis, representing the occluso-gingival direction.