1. Department of Oral Health, School of Dentistry, PO Box 647, The University of Otago, Dunedin, New Zealand,
2. Department of Pathology, Dunedin School of Medicine, The University of Otago
3. Department of Oral Sciences and Orthodontics, School of Dentistry, The University of Otago
4. Department of Preventive and Social Medicine, Dunedin School of Medicine, The University of Otago