1. Faculty of Dentistry; University of Medical Science; La Habana Cuba
2. The University of Hong Kong; Prince Philip Dental Hospital; Hong Kong China
3. University of Zurich; Zurich Switzerland
4. Dipartimento di Scienze Odontostomatologiche; Reparto di chirurgia orale; Università di Bologna; Bologna Italy
5. Faculdade de Odontologia de Araçatuba; UNESP - Universidade Estadual Paulista; Paulista Brasil
6. ARDEC; Ariminum Odontologica; Rimini Italy