1. Periodontology Department; Faculty of Dentistry; Hacettepe University; Ankara Turkey
2. Periodontology Department; Faculty of Dentistry; Kirikkale University; Kirikkale Turkey
3. Periodontology Department; Faculty of Dentistry; Katip Celebi University; Izmir Turkey
4. Biostatistics Department; Faculty of Medicine; Hacettepe University; Ankara Turkey