Accuracy of a 3D printed custom resin crossbar for complete arch implant scanning: An in vitro and in vivo study.

Abstract

Statement of problem: The accuracy of intraoral scanners for implant-supported prostheses in edentulous jaws is unclear with limited clinical evidence.

Purpose: The purpose of this in vitro and in vivo study was to evaluate the accuracy of a novel 3-dimensionally (3D) printed custom resin scanning crossbar (3D-CRC) for digital scans of complete arch implants and to provide a clinical benchmark.

Material and methods: Four implants were placed on a completely edentulous master model for in vitro scanning. Accuracy was compared among the conventional splinted open tray impression (CI) and 4 digital scanning groups: cylindrical scan bodies (DC), metal crossbars (DMC), digital wings (DW), and 3D-CRC (DRC). The digital group was scanned using the iTero Element 5D Plus (IT), Medit i500 (MD), and TRIOS 5 (TR) scanners, whereas the reference model was scanned using a laboratory scanner. The trueness, precision, linear and angular deviations, and efficiency were evaluated. A self-controlled in vivo study involving 12 participants compared CI and 3D-CRC-assisted digital scans. Root mean square (RMS), linear and angular deviations, and chairside time were evaluated. Aluminum frameworks were fabricated from the scan data and clinically tested for passive fit using the Sheffield test and radiographic examination. Data were analyzed with analysis of variance and paired t tests (α=.05).

Results: No significant accuracy differences were found between TR and MD scanners (P>.05), both showed higher accuracy than IT (P≤.001). Trueness did not differ significantly between the DRC and CI groups. DRC outperformed the DC (P<.001) and DMC (P=.01) for IT, as well as the DW (P=.044) for MD. Precision was comparable between DRC and CI for IT and MD (P>.05). However, CI surpassed DRC (P=.012), DW (P<.001), DMC (P=.006), and DC (P<.001) for TR, whereas DRC outperformed DW, DMC, and DC (P<.001). Linear deviation analysis showed that DRC performed better than DW (P=.038), DMC (P=.001), and DC (P<.001) for MD and better than DMC and DC (P<.001) for IT. In vivo, aluminum frameworks demonstrated a good passive fit in clinical fit assessments, with an RMS of 43.3 ±19.1 µm.

Conclusions: The 3D-CRC may improve the accuracy and operational efficiency of digital scans of edentulous arches, reducing linear and angular deviations compared with other scanning methods.