Accuracy of 9 intraoral scanners for complete-arch image acquisition: A qualitative and quantitative evaluation

Statement of problem. Different intraoral scanners (IOSs) are available for digital dentistry. However, information on the accuracy of various IOSs for complete-arch digital scans is limited. Purpose. The purpose of this in vitro study was to evaluate the trueness and precision of complete-arch digital scans produced by 9 IOSs, using the superimposition method, and to compare them based on characteristics including the data capture principle and mode and the need for powder coating. Material and methods. Nine IOSs were used to obtain standard tessellation language (STL) data for a bimaxillary complete-arch model with various cavity preparations (N=10). The scanning performance was evaluated quantitatively and qualitatively. For quantitative evaluation, the images were processed and analyzed using 3-dimensional (3D) analysis software. After we superimposed the datasets, trueness was obtained by comparing it with the reference scan, and precision was obtained from intragroup comparisons. The IOSs were compared based on the data capture principle and mode and the need for powder coating. Statistical analyses were conducted using a Kruskal-Wallis test, followed by multiple Mann-Whitney U tests for pairwise comparisons among groups (alpha=.05). For qualitative evaluation, surface smoothness and sharp edge reproducibility of the digital images were compared. Results. The median precision values were lowest in the TRIOS model (average, 34.70 mu m; maximum, 263.55 mu m) and highest in the E4D model (average, 357.05 mu m; maximum 2309.45 mu m). Median average trueness values were lowest in the TRIOS model (42.30 mu m) and highest in the Zfx IntraScan model (153.80 mu m). The CS 3500 model had the lowest median maximum trueness values (450.75 mu m); the E4D model had the highest values (2680.55 mu m). Individual image and video sequence data captures showed similar median average trueness values (P>.05); the median maximum values of individual images were higher than those of the video sequence (P<.05). Swept source optical coherence tomography (SS-OCT) exhibited higher trueness values than those of other scanning principles (P<.05). The FastScan and True Definition, which require powder coating, showed significantly better trueness than other IOSs that did not require powdering (P<.05). The E4D, PlanScan, and Zfx IntraScan models had an increased tendency to produce images with imperfect surface features and to round off sharp edges. Conclusions. The E4D and Zfx IntraScan models did not perform as accurately as the other IOSs. The data capture principle of SS-OCT and the mode of individual image acquisition exhibited inferior trueness. The FastScan and True Definition, which require powder coating, exhibited better trueness. The qualitative aspects of the IOSs varied in terms of polygon shapes, sharp edge reproducibility, and surface smoothness.