1. Department of Restorative Dentistry; Faculty of Dentistry; University of Malaya; 50603 Kuala Lumpur Malaysia
2. Centre of Population Oral Health & Clinical Prevention Studies; Faculty of Dentistry; Universiti Teknologi MARA; 40450 Shah Alam Selangor Malaysia
3. Division of Population & Patient Health; Dental Institute; King's College London; London UK
4. Department of Community Oral Health and Clinical Prevention; Faculty of Dentistry; University of Malaya; 50603 Kuala Lumpur Malaysia
5. Department of Oral Biology and Biomedical Sciences; Faculty of Dentistry; University of Malaya; 50603 Kuala Lumpur Malaysia
6. Department of Prosthodontics; Faculty of Dentistry; Sana'a University; Sana'a Yemen
7. School of Dental Sciences; Newcastle University; Newcastle upon Tyne UK