Dr. Kee-Joon Lee is the professor and chairman of the Department of Orthodontics, Yonsei University College of Dentistry, Korea. He received Orthodontic specialty training and PhD degree from Graduate school, College of Dentistry, Yonsei University. He was a visiting scholar at the Department of Biochemistry, University of Pennsylvania School of Dental Medicine and also at the Division of Plastic Surgery, the Children’s Hospital of Philadelphia. He is currently an adjunct professor at the Department of Orthodontics, University of Pennsylvania. He has contributed many book chapters on biomechanics of miniscrew-driven orthodontics, non-extraction treatment in adults, up-to-date lingual orthodontic mechanics and surgery-first approach using TADs. He is the first who demonstrated the miniscrew-assisted rapid palatal expander (MARPE) for adults in AJO-DO for non-surgical transverse correction in adults. He has published many articles and case reports regarding the treatment of non-eruption, and total arch movement for hyperdivergent face in orthodontic journals including two cover issues in AJO-DO. His fields in research include clinical biomechanics regarding TADs application and the suture/bone responses to orthodontic stimulus.