[1] La Trobe Univ, La Trobe Rural Hlth Sch, Dept Oral Hlth & Dent, Bendigo 3550, Australia
[2] Univ Turku, Inst Dent, Dept Community Dent, Turku, Finland
[3] Kings Coll London, Inst Dent, Div Populat & Patient Hlth, London, England
[4] Univ Eastern Finland, Inst Dent, Kuopio, Finland
[5] Kuopio Univ Hosp, Dept Oral & Maxillofacial Surg, Kuopio, Finland
[6] Natl Inst Hlth & Welf, Living Environm & Hlth Unit, Kuopio, Finland
[7] Natl Inst Hlth & Welf, Hlth Monitoring Unit, Helsinki, Finland
[8] Univ Turku, Inst Dent, Dept Oral Dev & Orthodont, Turku, Finland