In-vitro accuracy of full arch scans with a systematic review of nine different scanning patterns

Abstract Objective Evaluation of the accuracy of direct digitization of maxillary scans depending on the scanning strategy. Materials and Method A maxillary model with a metal bar fixed between the second molars as a reference structure was digitized using the CEREC Primescan AC scanner (N = 225 scans). Nine scanning strategies were selected (n = 25 scans per strategy), differing in scan area segmentation (F = full jaw, H = half jaw, S = sextant) and scan movement pattern (L = linear, Z = zig-zag, C = combined). Accuracy was assessed by evaluating linear differences in the X, Y, and Z axes and angular deviations (α axial, α coronal, α total) compared to a reference dataset. Differences in accuracy were analyzed using Kruskal-Wallis and Mann-Whitney U tests. Precision was analyzed by the standard deviation of linear and angular aberrations (ISO 5725-1) (p < 0.05). Results Strategy FL showed significantly higher trueness and precision than FZ for VE (p = 0.009), VE(y) (p = 0.010), αoverall (p = 0.004), and αaxial (p = 0.002). Strategy FC demonstrated significantly better trueness than FZ for VE (p = 0.007), αoverall (p = 0.010), and αcoronal (p = 0.013). For scan segmentation, FL showed better accuracy for VE(y) (p = 0.001) and αaxial (p < 0.001) than HL. Strategy HL showed better trueness for VE(z) than FL and SL (p = 0.001, p = 0.002). The scanning patterns FL, FC, and HL exhibited the best performance for trueness and precision. Conclusions Scanning motion and segmentation significantly impact the accuracy and precision of full-arch scans. Clinical relevance: The scanning strategy is decisive for improving clinical workflow and accuracy of full-arch scans.