Quality Evaluation of Intraoral Scanners Using Reverse-Engineered Scan Body

The incorporation of intraoral scanners (IOS) into dental implantology has notably increased the efficiency of clinical workflows. One of the key features of any IOS system is their accuracy, which defines how well scanner digitizes the scanned surfaces. In this study, CARES RC Mono intraoral scan bodies (ISB) extracted from digitized dental arches were used to evaluate the digitization accuracy of one laboratory scanner (E4) and four intraoral scanners (Trios 3, Trios 4, Carestream 3600 and Primescan). The proposed accuracy evaluation method reverse-engineers the surface of the extracted intraoral scan body. It starts by identifying well-defined intraoral scan body surfaces, then creates their respective geometric primitives, and uses them to generate a CAD (computer-aided design) model on top of the scanned surface. Two measurement types were used: the accuracy of the created CAD model and the 3D surface deviation between each defined ISB part and the CAD model. This approach bypasses the conventional fine alignment method in favor of a more elaborate and versatile evaluation algorithm, which can be used to evaluate any cylindrical-shaped ISB. Nine parameters were evaluated for each extracted scan body. Based on these evaluations, E4 demonstrated the best results, followed by Primescan scanner. The remaining scanners showed only minor differences in accuracy between them.