Bohm Choi, Dong-Ok Lee, Sung-Seo Mo, Seong-Hun Kim, Ki-Ho Park, Kyu-Rhim Chung, Gerald Nelson, Seong Ho Han

A1. The temporary skeletal anchorage device used in this study, C-implant, requires higher removal torque compared to other orthodontic mini-implants because of its greater osseointegration potential. It also means that the C-implant allows application of multi-directional force system such as retraction combined with intrusion by concurrent use of intra- and intermaxillary elastics. In such cases clinicians are encouraged to use longer head parts for ease of engaging multiple elastic modules to the miniscrews. However, it also could raise concerns since increasing overall length of the miniscrews might add more pressure on the contact surface. Therefore, the objective of this study was to evaluate the effect of different length of the head components on the amount of compressive stress in the cortical bone surrounding orthodontic mini implants. The results showed that compressive stress was indeed increased but still within clinically acceptable range.