1. Department of Clinical Research; Periodontology Unit; UCL Eastman Dental Institute; London UK
2. Centre for Adult Oral Health, Periodontology Unit; QMUL Bart's and The London School of Dentistry and Hospital; London UK
3. Federal University of Pernambuco; Recife-Pernambuco Brazil
4. Biostatistics Unit; UCL Eastman Dental Institute; London UK
5. International Centre for Evidence-Based Oral Health; UCL Eastman Dental Institute; London UK
6. Department of Microbial Diseases; UCL Eastman Dental Institute; London UK