1. Oral and Maxillofacial Department; University of Pernambuco (FOP/UPE); Recife Brazil
2. CAPES Foundation; Ministry of Education of Brazil; Brasília Brazil
3. Periodontology Unit; UCL Eastman Dental Institute; London UK
4. Postgraduate Department; Federal University of Pernambuco (UFPE); Recife Brazil
5. Biostatistics Unit; UCL Eastman Dental Institute; London UK
6. Department of Prosthesis and Oral and Facial Surgery; Federal University of Pernambuco (UFPE); Recife Brazil