1. Division of Population and Patient Health; King's College London Dental Institute at Guy's; King's College and St Thomas' Hospitals; London UK
2. Departamento Académico de Odontología Social; Universidad Peruana Cayetano Heredia; Lima Perú
3. Department of Economics; University of Houston - Clear Lake; Houston TX USA
4. Department of Preventive & Restorative Dental Sciences; University of California San Francisco School of Dentistry; San Francisco CA USA