Accuracy of implant casts from conventional and digital impressions

Introduction: Studies demonstrated that the accuracy of intra-oral scanners can be compared with conventional impressions for most indications. However, little is known about their applicability to take impressions of multiple implants. Objective: compare the accuracy between digital and different conventional impression techniques in implants. Material and Methods: Two master models were made: one with parallel implants (Model 1)and another with uneven implants(Model 2). Model 1: 4 types of impressions (Group A: impressions with reposition copings; Group B: Open tray for dragging copings; Group C: Open tray with Splinted copings; Group D: Using 3M ™ True Definition Scanner system). Model 2: 3 types of impressions (Group E: impression with reposition abutments; Group F: Open tray for dragging copings, without splinting; Group G: Using 3M ™ True Definition Scanner system). Master casts and conventional impression casts were digitized with na laboratory scanner. STL data sets from the seven groups were superimposed to assess the 3D (global)deviations. Results: Model 1: The value for the sum in group D was 1,068,292, which was significantly lower than those of group A, B and C, which were shown to be 2,114,342, 2,165,491 and 1,265,918 respectively. Model 2: The group F was the most accurate with 1,257,835 and 1,660,975 and 1,489,328 for groups E and G respectively. Conclusion: The methods tested here for the digital impression of full arch models are able to achieve the accuracy of conventional impressions in the in vitro model. However, further in vivo studies are needed to confirm the in vitro results. Keywords: Digital models, intraoral scanner, implants, digital impression