In vitro analysis of 3D-printed implant casts: how print orientation affects accuracy in full arch implant casts?

This in vitro study evaluated the accuracy of 3D-printed implant models of a complete edentulous arch with different print orientations (POs).

An acrylic resin edentulous mandibular model provided with 4 straight multi-unit abutment (MUA) implant analogs was used. The model was scanned ten times using a desktop optical scanner (E4, 3Shape), and these scans were superimposed with the aid of reverse engineering (Geomagic Design X) to obtain a single reference cast for best representing the true geometry. Conventional impressions with open-tray splinted technique (n = 12) and digital impressions with an intraoral scanner (IOS) (Trios5, 3shape) (n = 12) were performed. The implant casts were designed using the IOS data (Model Designer, 3Shape). 3D-printed implant casts were manufactured via a digital light processing printer at 0-, 22.5-, 45-, 67.5-, and 90 degrees of PO (n = 12). Conventional and 3D-printed implant casts were scanned using the desktop optical scanner. The digital data of the scan bodies was superimposed on the casts. Virtual models were superimposed on reference data using metrology software (Geomagic Control X). Linear discrepancies on the x-, y-, and z-axes, 3D discrepancies, and angular discrepancies were measured. Linear discrepancies in axes and overall linear discrepancies were evaluated via the Kruskal-Wallis test and post-hoc Dunn's test. Angular discrepancies were assessed via one-way analysis of variance (ANOVA) and Tukey's pairwise comparison tests.

No significant differences were found in 3D or angular discrepancies between conventional models, IOS data, or 90-degree of PO (p > 0.05). The angular deviations of the 0-degree PO group were not significantly different from the conventional, IOS, and the 90-degree PO groups (p > 0.05); however, the 3D discrepancies were higher in this group (p > 0.05). The 3D discrepancies of the 90-degree PO group were significantly lower than those of the 0-, 45-, and 67.5-degree PO groups (p < 0.05). No significant difference was found in angular discrepancies between PO groups (p > 0.05).

IOS data are as accurate as conventional models. The highest accuracy of 3D-printed implant models can be obtained with 90 degrees of PO. PO does not influence the angular discrepancies of 3D-printed implant models.