1. Department Oral Medicine; Infection and Immunity, Division of Periodontology, Harvard School of Dental Medicine; 188 Longwood Avenue, Boston Massachusetts 02115
2. Department of Restorative Dentistry and Biomaterials Sciences; Harvard School of Dental Medicine; Boston Massachusetts 02115
3. Department of Periodontics, Columbia University, College of Dental Medicine, New York; New York
4. Department of Conservative Dentistry and Periodontology; Center of Dental Medicine University Hospital Jena, Friedrich Schiller University; Jena Germany
5. Department of Prosthodontics; Columbia University, College of Dental Medicine, New York; New York