Differences between laboratory scanner and intra-oral scanner regarding axes and distances of three implants in a curved line when using two types of intra-oral scan bodies: in vitro study

Background The objective of this study was to evaluate differences in the intra-implant distance, inter-implant distance, intra-implant axis and inter-implant axis of two different intra-oral scan bodies (ISBs) which are connected to three implants in a curved line by comparing laboratory scanner (LBS) versus an intra-oral scanner (IOS). Methods Printed model with three internal hexagon implant analogs at the locations of 12#, 13#, and 14# was produced. Two ISBs, MIS Dentsply Sirona (MIS) and Zirkonzhan (ZZ), with different geometries (MIS trapezoid, ZZ cylindrical) were scanned one time by using LBS (master model) followed by thirty scans with IOS. After each scan a stereolithography (STL) file was produced and each IOS STL file was superimposed with the LBS STL file (master model) by using three-dimensional (3D) analysis software PolyWorks ® 2020. A Kolmogorov–Smirnov test was performed followed by a Mann–Whitney test ( p < 0.05). Results Mean errors for inter-implant distance were significantly lower for MIS compared to the ZZ ( p < 0.05). In contrast, mean errors for intra-implant angle were significantly lower for ZZ compared to MIS ( p < 0.05). Mean error for inter-implant angle was significantly lower for MIS compared to ZZ only between 12# to 14# and no difference was found between the other couples ( p < 0.05). Conclusions ISB geometry influenced all four parameters: intra-implant distance, intra-implant angle, inter-implant distance and inter-implant angle. MIS ISB trapezoid geometry resulted significantly lower mean error regarding most parameters except intra-implant angle. ZZ ISB cylindrical geometry had a good impact only on the intra-implant angle.