1. Samariterhemmet Hospital Dental Clinic, Public Dental Health Services, Dragarbrunnsg 70, S-751 25 Uppsala, Sweden,
2. Department of Oral Microbiology, Faculty of Odontology, Goteborg University, Sweden
3. Department of Oral Diagnostics, School of Dentistry, Karolinska Institutet, Sweden
4. Department of Preventive Dentistry, Public Dental Health Services, Uppsala County Council, Sweden