1 Department of Oral and Maxillofacial Surgery, Postgraduate School of Dentistry, Tohoku University, Sendai, Japan. Electronic address: yamaken@dent.tohoku.ac.jp.
2 Department of Oral and Maxillofacial Surgery, Postgraduate School of Dentistry, Tohoku University, Sendai, Japan.
3 Dental Technicians Office, Tohoku University Hospital, Sendai, Japan.