Accuracy of full arch scans performed with nine different scanning patterns- an in vitro study

Evaluation of the accuracy of direct digitization of maxillary scans depending on the scanning strategy.

A maxillary model with a metal bar as a reference structure fixed between the second molars 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). Trueness 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. Statistical differences were analyzed using Kruskal-Wallis and Mann-Whitney U tests (p<0.017). Precision was analyzed by the standard deviation of linear and angular aberrations (ISO 5725-1) (p < 0.05).

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), α_overall (p = 0.010), and α_coronal (p = 0.013). For scan segmentation, F_L showed better trueness 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 for 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.

Scanning motion and segmentation have a significant impact on the trueness and precision of full-arch scans.

The scanning strategy is decisive in enhancing the clinical workflow and the accuracy of full-arch scans.