1. Department of Periodontology, Centre for Oral Health Sciences, Malmö University, Malmö, Sweden
2. Department of Oral and Maxillofacial Surgery, School of Dentistry, University of Copenhagen, Copenhagen, Denmark
3. Department of Periodontology, Centre for Oral Health Sciences, Malmö University, Malmö, Sweden and Department of Periodontology and Fixed Prosthodontics,
University of Bern, Bern, Switzerland