1. Department of Dental Propaedeutics and Prophylaxis, Medical University of Warsaw, Nowogrodzka 59 St., 02-006 Warsaw, Poland
2. Department of Periodontology and Oral Mucosa Diseases, Medical University of Warsaw, Binieckiego 6 St., 02-097 Warsaw, Poland
3. Department of Medicine, Surgery, and Pharmacy, University of Sassari, 07021 Sassari, Italy