1. Bristol Oral and Dental School; Department of Restorative Dentistry; Lower Maudlin Street Bristol UK BS1 2LY
2. CIBER Epidemiología y Salud Pública (CIBERESP); Iberoamerican Cochrane Centre, Biomedical Research Institute Sant Pau (IIB Sant Pau); Sant Antoni Maria Claret 167 Pavilion 18 Barcelona Catalunya Spain 08025
3. The University of Manchester; Division of Dentistry, School of Medical Sciences, Faculty of Biology, Medicine and Health; JR Moore Building Oxford Road Manchester UK M13 9PL
4. Queen Mary University of London; Clinical and Diagnostic Oral Sciences, Barts and The London School of Medicine and Dentistry; Turner Street Whitechapel London UK E1 2AD
5. University College London Medical School; London UK
6. Faculty of Dentistry, Universidad de la Frontera; Department of Pediatric Dentistry and Orthodontic; Temuco Chile