Abstract: Objective:?Evaluating the effect of a elastic auxiliary devices on the accuracy of full-arch scans captured with intraoral scanners (IOS).Methods:?A model of the mandibular edentulous jaw implant restoration (containing 4 implants) was 3D printed, and the model was scanned using a desktop scanner as reference group, followed by 5 different intraoral scanning techniques: ICam4D stereophotogrammetry (SPG group), standard scan bodies (cIOS group), scan bodies with transverse extension device (mIOS group), scan bodies with elastic assist device (eIOS group), and scan bodies with additional resin block (rIOS group) were subjected to digital impression making as experimental group, and the alternative body data were generated in EXOCAD software. Best-fit alignments of the experimental group separately and the reference data of the alternative body data were performed to calculate the 3D deviations of the five different intraoral scanning techniques. The Kruskal-Wallis test was used to analyze the root-mean-square (RMS) 3D differences in trueness and precision between the five impression techniques.Results:For trueness, the SPG group showed the smallest deviation and was significantly superior to the cIOS group (P＜0.05). For precision, the cIOS group had a significantly larger deviation than the other four groups (P＜0.01). Conclusions:?The use of elastic auxiliary devices reduces the overall 3D bias of intraoral scanning, and stereophotogrammetry techniques show optimal trueness and precision, both of which meet the accuracy needs of digital impressions for edentulous jaw implants.