191 Assistant Professor, Professor, Division of Orthodontics, Department of Dentistry, School of Medicine, Ewha Womans University. Visiting Scholar, Division of Orthodontics, Department of Dentistry, University of Nebraska Medical Center. Former Student, Department of Orthodontics, Graduate School of Clinical Dentistry, Ewha Womans University. Associate Professor, Division of Orthodontics, Department of Dentistry, College of Medicine, The Catholic University of Korea, St. Mary’s Hospital. Associate Professor, Department of Orthodontics, University of Ulsan College of Medicine, Asan Medical Center. Associate Professor, School of Mechanical and Automobile Engineering, Kunsan National University. Corresponding author: Youn-Sic Chun. Division of Orthodontics, Department of Dentistry, School of Medicine, Ewha Womans University, 911-1 Mok-dong, Yangcheon-gu, Seoul 158-710, Korea. +82 2 2650 5114; e-mail, yschun@ewha.ac.kr. Received August 27, 2010; Last Revision October 22, 2010; Accepted October 25, 2010. DOI:10.4041/kjod.2011.41.3.191 Effects of orthodontic mini-implant position in the dragon helix appliance on tooth displacement and stress distribution: a three-dimensional finite element analysis