1. Private Practice, Gdańskie Centrum Stomatologiczne filia w Gdyni, Gdynia, Poland
2. Department of Public Health and Social Medicine, Medical University of Gdańsk, Gdańsk, Poland
3. University Dental Clinic, Pomeranian Medical University, Szczecin, Poland
4. Department of Dental Prosthetics, Pomeranian Medical University, Szczecin, Poland