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

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 F _L showed significantly higher trueness and precision than F _Z for VE (p = 0.009), V _E (y) (p = 0.010), α _overall (p = 0.004), and α _axial (p = 0.002). Strategy F _C demonstrated significantly better trueness than F _Z for VE (p = 0.007), αoverall (p = 0.010), and αcoronal (p = 0.013). For scan segmentation, F _L showed better accuracy for V _E (y) (p = 0.001) and α _axial (p < 0.001) than H _L . Strategy H _L showed better trueness for V _E (z) than F _L and S _L (p = 0.001, p = 0.002). The scanning patterns F _L , F _C , and H _L 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.