Dr. Julia Harfin is Professor and Chairman of the Orthodontic Department at the School of Dentistry, Maimónides University, Buenos Aires, Argentina. Dr. Harfin was a member of the Executive Committee of the World Federation of Orthodontists from 2000 to 2010 and served as President of the International College of Dentists, Section IV (South America), from 2010 to 2012. She is also a Past President of the Argentine Society of Orthodontics, ALADO, the International College of Dentists (Argentine Chapter), and the Pierre Fauchard Academy (Argentine Chapter). She is an Honorary Member of the Chilean and Polish Orthodontic Societies. Dr. Harfin is the author of many journal articles and book chapters as well as two books, Orthodontic Treatment in Adult Patients (Editorial Médica Panamericana, 1st edn. 1999, 2nd edn. 2005) and Clinical Lingual Orthodontics (Editorial Médica Panamericana, 2009). She has delivered more than 200 courses throughout the world.Dr. Augusto Ureña is Associate Professor in the Orthodontic Department, School of Dentistry, Maimónides University, Buenos Aires, Argentina and is Director of the Clinical Orthodontic Department at the same university. Dr. Ureña has been a Lecturer at the University of Buenos Aires, El Salvador University, and the Argentine Society of Orthodontics, among others. He has also delivered more than 20 lectures at the Orthodontic Societies of the Dominican Republic, Ecuador, Brasil, Chile, Australia, and Paraguay. He is co-author of the book Clinical Lingual Orthodontics (Editorial Médica Panamericana, 2009).