1. Department of Periodontology, School of Dental Medicine Tufts University Boston Massachusetts USA
2. Division of Oral Surgery, Unit of Dentistry, Dental School, Faculty of Medicine and Surgery Vita Salute University and IRCCS San Raffaele Milan Italy
3. Department of Dental Public Health, Faculty of Dentistry King Abdulaziz University Jeddah Saudi Arabia
4. Division of Periodontology, School of Dental Medicine, Department of Surgical Sciences, Faculty of Medicine and Surgery University of Cagliari Cagliari Italy
5. Department of Periodontology, School of Dental Medicine State University of New York at Buffalo Buffalo New York USA