Comparison of dimensional accuracy in models fabricated using various impression techniques and replica systems for implants placed according to the all-on -four treatment concept

Purpose: To compare the inconsistencies of press-fit and screw-retained digital implant replicas in models obtained from different 3D printers using intraoral and extraoral digital impression techniques with the conventional method. Methods: An all-on-four concept edentulous maxillary model was fabricated. Two models were prepared with two manufacturing methods: conventional group (CNV group) and additive manufacturing group (AM group). The AM group was fabricated in two different technologies (SLA and LCD) 3D printers from impressions taken with an intraoral scanner and a model scanner. The AM group was further subdivided into press fit replicas and screw-retained replicas. The position of each abutment replica was measured with a coordinate measuring machine (CMM). Results: Models produced with the Anycubic printer gave inconsistent results in the z-axis (10.449 gm for group AM-5, 10.407 gm for group AM-6, 10.454 gm for group AM-7 and 10.43 gm for group AM-8). The other groups showed similar results in x-, y- and z-axis. The CNV group showed significant differences from some groups for XZ angle and YZ angle. IOS, EOS and conventional impression techniques showed similar accuracy. The screw-retained digital replica group showed better results than the press-fit digital replica group, but no significant difference was found. The Anycubic printer provided the least accurate values for implant replica positions, as it showed the highest discrepancy values on the vertical axis.