1. Division of Oral and Maxillofacial Surgery, Kagawa Prefectural Central Hospital, No. 1-2-1, Asahi-cho, Takamatsu, Kagawa 760-8557, Japan
2. Department of Oral and Maxillofacial Surgery, Shimane University Faculty of Medicine, No. 89-1, Enya-cho, Izumo, Shimane 693-8501, Japan
3. Kawakami Orthodontic Clinic, No. 1-3-30, Ban-cho, Takamatsu, Kagawa 760-0017, Japan