A R Tappuni1, R Al-Kaabi2, E Joury3. 1. 1 Institute of Dentistry, Queen Mary University of London, London, UK. 2. 2 Directorate of Preventive Health Affairs, Directorate General of Health, Duhok, Iraq. 3. 3 Population and Patient Health, King's College London Dental Institute, King's College London, London, UK.