1. Private Practice Medellin Colombia
2. Department of Periodontics and Oral Medicine, School of Dentistry University of Michigan Ann Arbor Michigan USA
3. Department of Oral Pathology, Oral Medicine and Oral and Maxillofacial Surgery School of Dentistry University of Tripoli Tripoli Libya
4. Private Practice Barquisimeto Venezuela
5. Department of Periodontics, School of Dentistry University of Zawia Zawia Libya