Effect of print angle on dimensional accuracy and printing efficiency of directly 3D-printed clear aligners.

This study evaluated the effect of print angulation on the dimensional accuracy and production efficiency of directly 3D-printed clear aligners fabricated with a high-resolution LCD printer and a clinically available, FDA-cleared clear resin (Clear Miracle Resin; ODS Co., Ltd., Inchon, Korea). Seventy aligners were produced in seven orientations (0°, A30°, A60°, A90°, P30°, P60°, P90°) with a 50-µm layer height. Dimensional accuracy was assessed using root mean square (RMS) deviation, linear and angular measurements, and height analysis complemented by color-coded deviation maps. Printing time was also recorded. Statistical comparisons were performed using the Kruskal–Wallis test with post-hoc analysis at a significance level of 0.05. Print angulation significantly influenced RMS as well as linear, angular, and height deviations. The 0° orientation achieved the lowest RMS and the shortest print time, while A90° and P90° showed higher deviations and greater vertical reduction. All groups exhibited negative height deviations, with the 0°, P30°, and P60° orientations demonstrating minimal deviations. These findings indicate that print angulation measurably affects both accuracy and efficiency of direct aligner printing. The 0° orientation provided the most accurate fit, fastest production, and good predictability, underscoring the importance of angulation selection.