1 Dentist, City of Akaa Health Center, Akaa, Finland.
2 Professor, Department of Oral Pathology and Radiology, University of Turku, Turku, Finland; Oral Pathologist, Helsinki University Hospital, Helsinki, Finland.
3 Clinical Lecturer, Institute of Dentistry, School of Medicine, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland; Oral Health Teaching Clinic and Oral and Maxillofacial Diseases Clinic, Kuopio University Hospital, Kuopio, Finland. Electronic address: maria.siponen@uef.fi.