Comparison of the accuracy between conventional and various digital implant impressions for an implant-supported mandibular complete arch-fixed prosthesis: An in vitro study

Purpose This in vitro study compared the accuracy between conventional and different intraoral scanner impression methods and stereophotogrammetry term of 3D deviation for a complete mandibular edentulous arch with 5 placed implants. Materials and methods An edentulous mandibular model was prepared with three straight and two 17 degrees angled screw-retained abutments screwed on implants. Different impression techniques were compared: one conventional impression, CO (open-tray splint impression coping, Polyether), three groups of intraoral scanners, TS (Trios 4), IT (iTero Element 2), and PS (Primescan), and one stereophotogrammetry, PIC (Precise Implants Capture). An extraoral scanner (E4 scanner) was used to digitize the reference model as a control group. Scan body positions were compared with 3D deviation by using a 3D analysis software program (Geomagic ControlX 2020.1.1) with the best-fit alignment technique. The accuracy of the scan bodies' position of each impression technique between each group area was analyzed using one-way ANOVA followed by Scheffe's comparison test for trueness and precision. (alpha = 0.05). Results Statistical 3D deviations of the whole scan body were found among the CO, TS, PS, IT, and PIC groups for both trueness (p < 0.05) and precision (p < 0.05). PIC showed the least 3D deviation of trueness (48.74 +/- 1.80 mu m) and precision (5.46 +/- 1.10 mu m), followed by TS, PS, IT, and CO. CO had the highest 3D deviation of trueness (141 +/- 5.58 mu m) and precision (40.4 +/- 1.3.39 mu m), which was significantly different from PIC, TS, and PS. Conclusions For completed-arch digital implant impressions, stereophotogrammetry has shown better accuracy than other digital and conventional impression techniques, especially in terms of precision. The highest 3D deviation was found in the conventional splint open-tray impression technique.