1. Department of Maxillofacial Surgery, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba 271–8587, Japan
2. Department of Fixed Prosthodontics and Oral Implantology, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba 271–8587, Japan
3. Departments of Pathology, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba 271–8587, Japan
4. Department of Dentistry and Oral Surgery, Yokohama Rosai Hospital, Yokohama, Kanagawa 222–0036, Japan