Scanning Accuracy With Splinted and Unsplinted Implant Scan Bodies for the Edentulous Arch at the Implant Level: An...

Accuracy of completely edentulous arch scanning with implant scan bodies has not been completely validated for intraoral scanners. For desktop laboratory scanners, validations were found in the literature. The aim of this in vitro study was to compare the dimensional accuracy of scanning with splinted and unsplinted scan bodies on a completely edentulous maxillary arch with 6 implants. A maxillary edentulous master cast with 6 implants was used as a control for all implant level impressions. Six implants were digitally planned and placed at different angulation of 0°, 17°, and 30°. A contact coordinate measuring machine (CMM) was used to generate baseline linear measurements of the master cast. Four test groups included 2 intraoral scanners, Trios (3shape, Copenhagen, Denmark) and True Definition (3M ESPE, St Paul, Minn); 1 industrial scanner, Atos (Core optical 3D scanner); and 1 conventional impression group scanned with the laboratory scanner Dental Wings 7 Series. Each scan recording was made with splinted and unsplinted scan bodies. Digital data sets of all measurements were compared with the CMM baseline values using PolyWorks InnovMetric Software in order to assess the linear and angular deviations and determine the accuracy of complete arch digital impression. Factorial analysis of variance showed significant effect with splinting, scanner type, interimplant distance, and implant angulation for linear deviations. Splinted scan bodies revealed elevated linear and angular deviation values for all scanners with significantly highest deviations for the True Definition scanner. Significant correlation was found between interimplant distance and linear deviation (r = 0.45, P ≤ .001) with increased linear deviations among all scanners regardless of splinting (P < .05). A significant effect on accuracy was seen for angular deviation with splinting, scanner type, and implant angulation; a significant difference was found between 0° and 30° implant angulation (P = .035) with more deviation with the 30° implant angulation. The accuracy of the complete arch implant digital impression using splinted scan bodies was significantly reduced for measurements that crossed the arch midline. The digital impression technique using a broad splint design to connect scan bodies was not found to improve the scan accuracy for intraoral scanners.