1. Department of Periodontics, School of Dental Medicine and Departments of Pathology and Reproductive Biology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106 USA;
2. Department of Periodontology and Oral Biochemistry, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University, Gustav Mahlerlaan 3004, 1081 LA Amsterdam, The Netherlands;
3. Department of Periodontics, School of Dentistry, Virginia Common wealth University, PO Box 980566, Richmond, VA, USA; and
4. Department of Oral Biology, School of Dental Medicine, The State University of New York at Buffalo, 202 Foster Hall, Buffalo, NY 14214, USA;