Evaluation of the trueness of digital implant impressions according to the implant scan body orientation and scanning method

This study investigated the trueness of a digital implant impression according to the orientation of the implant scan body (ISB) and the scanning method. With the flat surface of the ISB facing either the buccal or proximal direction, the ISB was scanned using one tabletop scanner (T500) and three types of intraoral scanner (TRIOS 3, CS3600, and i500). The effects of differences in the scanning method and ISB orientation were assessed. Postalignment data were subsequently obtained with the abutments generated using a digital library, and superimposed with reference data using a best-fit algorithm, followed by root-mean-square error (RMSE) analysis. The RMSE was lower in the buccal groups (28.15 + 8.87 um, mean + SD) than in the proximal groups (31.94 + 8.95 um, p = 0.031), and lower in the full-scan groups (27.92 + 10.80 um) than in the partial-scan groups (32.16 + 6.35 um, p = 0.016). When using the tabletop scanner, the trueness was higher when the ISB was connected buccally (14.34 + 0.89 um) than when it was connected proximally (29.35 + 1.15 um, p < 0.001). From the findings of this study it can be concluded that the operator should connect the ISB so that its flat surface faces the buccal direction, and attempt to scan all areas. Additionally, it is advantageous to connect an ISB buccally when using a tabletop scanner.