1. Department of Surgery, Faculty of Medicine, University of Salamanca, 37007 Salamanca, Spain
2. School of Dentistry, Catholic University of Cuenca, Cuenca 010107, Ecuador
3. Latin American Network of Research on Fluorides and Dental Fluorosis, Cartagena 130009, Colombia
4. Private Consultation, Cuenca 010107, Ecuador
5. School of Dentistry, Hemisferios University, Quito 170527, Ecuador
6. Faculty of Medicine and Dentistry, Department of Stomatology, University of Valencia, 46010 Valencia, Spain