1. Department of Microbiology, Medical School National and Kapodistrian University of Athens Athens Greece
2. Department of Prosthodontics, School of Dentistry Aristotle University of Thessaloniki Thessaloniki Greece
3. Department of Prosthodontics, School of Dentistry National and Kapodistrian University of Athens Athens Greece
4. Division of Prosthodontics, Department of Restorative Dental Sciences College of Dentistry University of Florida Gainesville FL