1. Unit of Periodontics and Dental Hygiene, Department of Innovative Technologies in Medicine & Dentistry University ‘G. D'Annunzio’ of Chieti‐Pescara Chieti Italy
2. Department of Periodontics and Preventive Dentistry University of Pittsburgh School of Dental Medicine Pittsburgh Pennsylvania USA
3. Department of Periodontics and Oral Medicine University of Michigan School of Dentistry Ann Arbor Michigan USA