1. Department of Oral Surgery, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba 271-8587, Japan
2. Nihon University Graduate School of Dentistry at Matsudo, Oral and Maxillofacial Surgery, Matsudo, Chiba 271-8587, Japan
3. Department of Pathology, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba 271-8587, Japan