K J Chen1, W F Lo2, I Chen3, M Y C Chen4. 1. Division of Oral & Maxillofacial Surgery, Dental Department, China Medical University Hospital, Taichung, Taiwan. Electronic address: speach1026@gmail.com. 2. Division of Oral & Maxillofacial Surgery, Dental Department, China Medical University Hospital, Taichung, Taiwan. Electronic address: u9400020@cmu.edu.tw. 3. Division of Oral & Maxillofacial Surgery, Dental Department, China Medical University Hospital, Taichung, Taiwan. Electronic address: stevenash1394@hotmail.com. 4. Division of Oral & Maxillofacial Surgery, Dental Department, China Medical University Hospital, Taichung, Taiwan; College of Dentistry, China Medical University, Taichung, Taiwan. Electronic address: mychen@mail.cmuh.org.tw.