Accuracy of digital versus conventional multiple implant impression procedures using 3-dimensional super imposition technique - An in-vitro study.

PURPOSE: To compare the accuracy of digital and conventional impression techniques in completely edentulous model and to determine the effect of different variables on the accuracy outcomes.MATERIALS AND METHODS: An edentulous maxillary model with six implants was prepared to serve as master cast (control) for both conventional and digital implant impression technique. Digital impressions (n = 5) were taken with an intraoral optical scanner (TRIOS, 3shape, Denmark) after connecting polymer scan bodies. For the conventional impressions of the master cast, window tray and chimney tray technique were used for implant-level impressions (n = 5 each). Master casts and conventional impression casts were digitized with an extraoral high-resolution scanner (IScan D103i, Imetric, Courgenay, Switzerland) to obtain digital volumes. Standard tessellation language (STL) datasets from the 3 groups of digital and conventional impressions were superimposed with the STL dataset from the master cast to assess the 3D (global) deviations. To compare the master cast with digital and conventional impressions at the implant level Geomagic Freeform; Geomagic Control X (superimposition software) were used to calculate the 3D deviation.RESULTS: Results of this study revealed that the accuracy of digital impressions is the same as that of conventional impressions. About the implants, the digital impressions of six maxillary implants resulted in similar accuracy to the conventional techniques.CONCLUSION: Digital implant impressions are as accurate as conventional implant impressions. Both, digital impressions and chimney tray techniques were superior to the window tray impression technique.