1. Department of Periodontology and Prosthodontics; Eastman Dental Hospital; Roma; Italy
2. Periodontics, School of Dental Science; University of Melbourne; Parkville; Vic.; Australia
3. Department of Periodontics; Nova Southeastern University; Ft. Lauderdale; FL; USA
4. Division of Fixed Prosthodontics; University of Bern; Bern; Switzerland
5. Clinic for Fixed and Removable Prosthodontics and Dental Materials; School of Dental Medicine; University of Zurich; Zurich; Switzerland