Accuracy of 3D white light scanning of abutment teeth impressions: Evaluation of trueness and precision

Purpose. This study aimed to evaluate the accuracy of digitizing dental impressions of abutment teeth using a white light scanner and to compare the findings among teeth types. Materials and methods. To assess precision, impressions of the canine, premolar, and molar prepared to receive all-ceramic crowns were repeatedly scanned to obtain five sets of 3-D data (STL files). Point clouds were compared and error sizes were measured (n=10 per type). Next, to evaluate trueness, impressions of teeth were rotated by 10°-20° and scanned. The obtained data were compared with the first set of data for precision assessment, and the error sizes were measured (n=5 per type). The Kruskal-Wallis test was performed to evaluate precision and trueness among three teeth types, and post-hoc comparisons were performed using the Mann-Whitney U test with Bonferroni correction (α=.05). Results. Precision discrepancies for the canine, premolar, and molar were 3.7 μm, 3.2 μm, and 7.3 μm, respectively, indicating the poorest precision for the molar (P < .001). Trueness discrepancies for teeth types were 6.2 μm, 11.2 μm, and 21.8 μm, respectively, indicating the poorest trueness for the molar (P=.007). Conclusion. In respect to accuracy the molar showed the largest discrepancies compared with the canine and premolar. Digitizing of dental impressions of abutment teeth using a white light scanner was assessed to be a highly accurate method and provided discrepancy values in a clinically acceptable range. Further study is needed to improve digitizing performance of white light scanning in axial wall.