1. Department of Periodontics, Yantai Stomatological Hospital, Yantai, P.R. China.
2. Department of Prosthetics, Yantai Stomatological Hospital, Yantai, P.R. China.
3. Department of Oral and Maxillofacial Surgery, Yantai Stomatological Hospital, Yantai, P.R. China.
4. Department of Oral Implantology, Yantai Stomatological Hospital, Yantai, P.R. China.