1. Department of Oral and Maxillofacial Diseases, Mikkeli Central
Hospital, Porrassalmenkatu 35-37, FIN-50100 Mikkeli, Finland;
2. Central Military Hospital, Helsinki, Finland;
3. National Public Health Institute, Helsinki, Finland; and
4. Institute of Dentistry, University of Helsinki, and Department of
Oral and Maxillofacial Diseases, Helsinki University Central Hospital, Finland;