Efficacy of two different layer heights on the accuracy of 3-D printed orthodontic models

Aim: This study aimed to assess the accuracy of the 3D printed model by DLP technology at 50-µm and 100-µm layer height Materials and Methods: A desktop scanner, R700 desktop scanner (3Shape, Copenhagen, Denmark) was used to scan an orthodontic typo-dent cast. A total number of (20) models were printed using a Digital Light Processing 3D printer and divided into two separate group. The 1 st group (n=10) and the 2 nd (n=10) groups were printed at 50-μm and 100-μm layer heights respectively. Assessment was performed using the GOM Inspect suite to register both the reference and 3D printed digital models to detect the deviation in both X, Y, and Z axes. Results: Data were presented as mean and standard deviation values and were tested for normality using Shapiro-Wilk test. Data were non-parametric and were tested using Wilcoxon signed rank test. The significance level was set at p≤0.05 within all tests. In the molar area, 50-µm layer thickness showed statistically significant difference in the right side when compared with 100-µm. In the premolar region, there was no statistically significant differences between both groups in the right side except for the z-axis. The canine area demonstrated that the 50-µm layer height was statistically significant lower in deviation than 100-µm group in all directions. There was a strong agreement between both observers (ICC=0.965, 95%CI= (0.958:0.971), p<0.001). Conclusion: the results of our research as a whole show that models printed at 50-μm display lower deviations in X, Y, and Z axes with a more consistent distortion pattern when compared to 100-μm models. Besides, the ideal thickness for high precision requirements is 50 µm, whereas 100-μm could be used in printing diagnostic models.