1. Dental and Oral Medical Center, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka 830-0011, Japan
2. Seattle Science Foundation, 550 17th Ave, James Tower, Suite 600, Seattle, WA 98122, USA
3. Department of Dental and Oral Surgery, Saiseikai Hita Hospital, 643-7 Miwa, Hita, Oita 877-0000, Japan