1. Research Centre for the Study of Periodontal and Peri-Implant Diseases; University of Ferrara; Ferrara Italy
2. Operative Unit of Dentistry; University-Hospital of Ferrara; Ferrara Italy
3. Department of Dentistry; State University of Maringá; Maringá Brazil
4. Division of Periodontology; College of Dentistry; The Ohio State University; Columbus OH USA