[1] Hiroshima Univ Hosp, Dept Oral & Maxillofacial Radiol, Minami Ku, Hiroshima 7348553, Japan
[2] Hiroshima Univ, Grad Sch Biomed Sci, Dept Oral & Maxillofacial Radiol, Div Med Intelligence & Informat, Hiroshima, Japan
[3] Hiroshima Univ, Grad Sch Biomed Sci, Dept Obstet & Gynecol, Div Clin Med Sci, Hiroshima, Japan
[4] Aichi Gakuin Univ, Sch Dent, Dept Periodontol, Nagoya, Aichi 464, Japan