Abstract: Objective: To compare the accuracy of three intraoral scanner-based complete arch implant impression techniques using TRIOS 3 and Aoralscan 3 intraoral scanners. Methods: A standard edentulous maxillary implant model with 6 screw-retained abutment-level scan bodies was constructed. The scan bodies were numbered from 1 to 6, from the right molar to the left molar area. A control group was generated by scanning the implant model using a desktop scanner. Three intraoral scanner-based scanning techniques were tested: without any scan aids，with scan aids but without calibration, and with scan aids and perform calibration. The tests were performed on 2 intraoral scanners: 3Shape TRIOS 3 and Shining3d Aoralscan 3. Each technique was repeated 10 times on each scanner. Scan bodies in the tested groups were superimposed onto the control group using scan bodies #1 and #2 as references to simulate the single-screw test. For each scan body, the distance between the centers of the screw-retained abutments in the test and control groups was measured to calculate trueness. The distance between the centers of the screw-retained abutments in each pair of scans within each test group was also measured to calculate precision. Trueness and precision of the 3 tested impression techniques were compared. Results: In both tested scanners, the trueness of the scanning group with scan aids (272.32 μm for TRIOS 3; 240.00 μm for Aoralscan 3) was higher than that of the group without any scan aids (606.77 μm for TRIOS 3; 413.78 μm for Aoralscan 3) (all P<0.05). Furthermore, the calibration process further improved trueness (70.51% improvement for TRIOS 3; 28.00 % improvement for Aoralscan 3 ). For precision, the scanning group with scan aids (75.60 μm for TRIOS 3; 69.91 μm for Aoralscan 3) and the group with calibration (74.36 μm for TRIOS 3; 79.42 μm for Aoralscan 3) outperformed the group without any scan aids (487.75 μm for TRIOS 3; 160.74 μm for Aoralscan 3) (all P<0.05). However, there was no statistically significant difference between the scanning group with scan aids and the group with calibration (P>0.05). Conclusion: The accuracy of intraoral scanning for full-arch implant impressions can be significantly improved by using scan aids combined with a calibration process.