Comparison of Horizontal and Vertical Tooth Movements in Erkodur vs. Zendura FLX Clear Aligners The objective of this study was to assess and compare horizontal and vertical tooth movements between two clear aligner materials, Erkodur and Zendura FLX. Nineteen participants were divided into two groups, and received either Erkodur or Zendura FLX aligners, with digital models obtained at intervals over six months. Horizontal and vertical tooth movements were measured and compared using statistical tests, including the Mann-Whitney U test for overall movement and the Wilcoxon Signed-rank test for individual tooth movement between both groups. Overall, horizontal tooth movements between Erkodur and Zendura FLX were not statistically different, but vertical movements showed significant differences at the fifth and sixth months (p < 0.05). Significant differences between predicted and achieved horizontal tooth movement (p < 0.05) were observed for Erkodur on teeth 11, 41, and 35, and for Zendura FLX on teeth 17, 16, 25, 27, 45, 44, 41, 32, 36, and 37, predominantly indicating overcorrection, except for teeth 11 and 41 in the Erkodur group and tooth 41 in the Zendura group. Significant differences in vertical tooth movement (p < 0.05) were identified for Erkodur on teeth 14, 13, 11, 27, 44, 35, and 37, and for Zendura FLX on teeth 47, 45, and 44. Erkodur and Zendura FLX revealed no significant differences in initial horizontal tooth movements. However, significant disparities between the materials emerged in later stages of treatment, with both exhibiting notable discrepancies between predicted and achieved movement in both vertical and horizontal tooth movements over a sixmonth interval.