1 Department of Prosthodontics, Faculty of Odontology, Malmö University, 205 06 Malmö, Sweden.
2 Department of Chemical and Biological Engineering, Applied Surface Chemistry, Chalmers University of Technology, 412 96 Gothenburg, Sweden.
3 Department of Periodontology and Oral Implantology, Dental School, Faculty of Medicine and Health Sciences, University of Ghent, 9000 Ghent, Belgium.