1 1 Department of Dentistry, Oral and Maxillofacial-Plastic and Reconstructive Surgery, Faculty of Medicine, Yamagata University, Yamagata, Japan.
2 2 Department of Dentistry and Oral Surgery, Nihonkai General Hospital, Yamagata Prefectural and Sakata Municipal Hospital Organization, Yamagata, Japan.
3 3 Department of Dentistry, Oral and Maxillofacial Surgery, Okitama Public Hospital, Yamagata, Japan.