1. Halton & St Helens Primary Care Trust, Victoria House, The Holloway, Runcorn, Cheshire WA7 4TH, UK;
2. Dental Public Health & Primary Care, School of Dentistry, The University of Manchester, Higher Cambridge Street, Manchester, M15 6FH, UK; and
3. Faculty of Dentistry, University of Sydney, Westmead, New South Wales 2145, Australia