1. University of Newcastle upon Tyne, The Dental School, Framlington Place, Newcastle upon Tyne, NE2 4BW, UK
2. Ohio State University, Department of Primary Care, College of Dentistry, 305 West 12th Ave., PO Box 182357, Columbus, OH 43218, USA
3. Ohio State University, Department of Periodontology, College of Dentistry, Department of Pharmacology, College of Medicine, 305 West 12th Ave, PO Box 182357, Columbus, OH 43218-2357, USA