1. Department of Prosthodontics, Faculty of Odontology; Malmö University; 205 06 Malmö Sweden
2. Department of Chemistry and Chemical Engineering, Applied Chemistry; Chalmers University of Technology; 412 96 Gothenburg Sweden
3. Department of Clinical Dentistry; Center for Clinical Dental Research, University of Bergen; Norway
4. Department of Oral and Maxillofacial Surgery and Oral Medicine, Faculty of Odontology; Malmö University; 205 06 Malmö Sweden