1. Centre for Clinical Research, Uppsala University, Västerås, Sweden;
2. Public Dental Clinic Sala, Public Dental Health Västmanland, Sala, Sweden;
3. Faculty of Odontology, Malmö University, Malmö, Sweden;
4. Department of Family Medicine, College of Human Medicine, Michigan State University, Grand Rapids, MI, USA;
5. Fersens Väg, Malmö, Sweden