Digital evaluation of the reproducibility of implant scanbody fit-an in vitro study

Dental restorations are increasingly manufactured by CAD/CAM systems. Currently, there are two alternatives for digitizing dental implants: direct intra-oral data capturing or indirect from a master cast, both with transfer caps (scanbodies). The aim of this study was the evaluation of the fit of the scanbodies and their ability of reposition. At the site of the first molars and canines, implants were placed bilaterally in a polymer lower arch model (original model), and an impression was taken for fabricating a stone cast (stone model). Ten white-light scans were obtained from the original and the stone model with the scanbodies in place. The scanbodies were retrieved after each scan and re-attached to the same implant or lab analogue. The first scan of the series served as control in both groups. The subsequent nine scans and control were superimposed using inspection software to identify the discrepancies of the four scanbodies in both experimental groups. The systematic error of digitizing the models was 13 mu m for the polymer and 5 mu m for the stone model. The mean discrepancy of the scanbodies was 39 mu m (+/- 58 mu m) on the original implants versus 11 mu m (+/- 17 mu m) on the lab analogues. The difference in scanbody discrepancy between original implants and lab analogues was statistically significant ( < 0.05, Mann-Whitney test). Scanbody discrepancy was higher on original implants than on lab analogues. Fit and reproducibility of the scanbodies on original implants should be improved to achieve higher accuracy of implant-supported CAD/CAM fabricated restorations.