1. Institute of Dentistry, University of Oulu, Finland, Oulu Municipal Health Center, Oulu, Finland, present adress, University of Toronto, Faculty of Dentistry, 124 Edawrd Street, Toronto, ON, MSG IG6, Canada,
2. Institute of Dentistry, University of Oulu, Finland
3. Faculty of Medicine, University of Helsinki, Finland
4. Institute of Dentistry, University of Oulu, Finland, Oulu University Hospital, Oulu, Finland