1. Oral Surgery, Akita University School of Medicine, Akita. Japan.
2. Department of Dentistry and Oral Surgery, National Sendai Hospital, Sendai, Japan.
3. Clinics for Maxillo-oral Disorders; Tohoku University School of Dentistry, Sendai, Japan.
4. Department of Prosthetics II; Tohoku University School of Dentistry, Sendai, Japan.
5. Department of Geriatric Dentistry;Tohoku University School of Dentistry, Sendai, Japan.
6. Department of Oral and Maxillofacial Surgery II, Tohoku University School of Dentistry, Sendai, Japan.