Affiliation: | a Dental School, Department of Preventive Dentistry, Periodontology and Biology of Implants, Aristotle University of Thessaloniki, University Campus, 54124 Greece b Periodontology and Pathology, University of Pennsylvania School of Dentistry, School of Dental Medicine, 240 South 40th Street, Philadelphia, PA 19104-6030, USA c School of Dentistry, University of Louisville, Louisville, KY 40202, USA |