1. Department of Periodontology,
2. Research Group for Microbial Adhesion, School of Dentistry, Oral Pathology and Maxillo-Facial Surgery, Faculty of Medicine, Catholic University of Leuven, Kapucijnenvoer 7, B-3000 Leuven, Belgium; and
3. Department of Periodontology, The Forsyth Institute, Boston, MA, USA;