1. Department of Periodontics/Prevention/Geriatrics, School of Dentistry, Rm. 3310M Dental, University of Michigan, 1011 N. University Avenue, Ann Arbor, MI 48109-1078, USA;
2. Department of Prosthodontics/Periodontics, Division of Periodontics, School of Dentistry at Piracicaba, University of Campinas, Brazil;
3. Department of Oral Pathology, Faculty of Dentistry, Hiroshima University, Japan;
4. Department of Developmental Biology and Howard Hughes Medical Institute, School of Medicine, Stanford University, CA, USA;
5. Department of Periodontics, School of Dentistry, University of Washington, Seattle, USA;