1. Department of Oral Implantology, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
2. Department of Stomatology, Sir Run Run Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
3. Department of General Dentistry, Eastman Institute for Oral Health, University of Rochester, Rochester, NY 14620, USA