1. a Profesor Asociado, Departamento de Odontología Social, Universidad Peruana Cayetano Heredia, Lima, Peru; PhD student, Department of Epidemiology and Public Health, University College London, London, UK
2. b Professor, Department of Epidemiology and Public Health, University College London, London, UK
3. c Post Doctorate Research in Orthodontics, Dental School, University of Manchester, Manchester, UK