1. Periodontology and Implant Dentistry Division, Faculty of Dentistry, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
2. School of Dentistry, Health Sciences Department, Magna Graecia University of Catanzaro, 88100 Catanzaro, Italy
3. Department of Orthodontics and Dentofacial Orthopaedics, Charité-Universitätsmedizin Berlin, Aßmannshauser Str. 4-6, 14197 Berlin, Germany