Evaluation of Accuracy of Intraoral Scanner with Different Inlay Preparation Geometry

Objective: This in vitro study aimed to assess the accuracy of an intraoral scanner in inlay preparations with different geometry. Methods: The upper second premolar tooth-shaped models were designed and prepared using a 3D printer (Phrozen Mega 8K, Phrozen, Taiwan). Three distinct inlay preparation configurations were utilized, including buccal and palatal wall divergence at 6 degrees, 8 degrees, and 10 degrees. The reference 3D images were acquired through scanning of each model with varying inlay preparation using an extraoral scanner (E1, 3Shape, Denmark). Thirty 3D images (samples) were obtained from each of the three models (n = 10) using an intraoral scanner (Trios 3, 3Shape, Denmark). The samples and reference images were saved in Standard Tessellation Language (STL) and imported into software (Geomagic Control X 2022, 3D Systems Inc., USA). Discrepancies between the reference image and the samples were recorded as root mean square (RMS) and standard deviation (SD). Kruskal Wallis and Mann Whitney U tests, and interquartile range (IQR) were used for statistical analysis with THE significance level p<.05. Results: The RMS was highest at 6 degrees, both of which were statistically significant from the other degrees (p<.001). Highest SD values were obtained in 10 degrees samples (p<.001). To evaluate the infer precision with IQR, RMS values were smallest at 10 degrees and SD values smallest at 6 degrees. Conclusion: The divergence angle of the preparation in the inlay cavities can potentially affect the accuracy of the intraoral scanner.