Three-Dimensional Accuracy of Virtual Casts Obtained from Intra Oral Scanners and Scannable Impression for Three Units Bridge

Abstract

Aims: For evaluation and comparison of the accuracy of different methods for virtual models obtaining techniques. Materials and methods: The reference cast was prepared for 3-unit fixed bridge. Four Groups with 8 samples in each group. Stone models were poured from conventional impressions. Digital impressions of the reference cast were created using two types of intraoral scanner defers in scanning technology and direct impression digitization. Reference cast, stone casts and scannable impressions were subsequently scanned using a laboratory optical scanner; files were exported in a stereolithography file format. All datasets were superimposed using 3D analysis software to evaluate the accuracy (trueness and precession). An independent-samples median test summary was performed to compare trueness among the four impression groups. The independent-samples Kruskal-Wallis test was performed to evaluate the precession of each group of impression techniques. Results: with regard to trueness, the Trios Group and Medit i500 Group had the highest trueness of all groups, with no significant differences between them, followed by the conventional impression group, then the scannable impression group which had the largest deviation from the reference model. None of the groups showed significant differences in precession. Conclusions: Intraoral scanners have a high accuracy level for both trueness and precession. Scannable impression direct digitization showed significantly higher deviation than conventional impression stone casts with clinically acceptable levels of accuracy.