1. King's College Dental Institute at Guy's Hospital, King's Health Partners, London.
2. CHU Clermont-Ferrand, Service d'Odontologie, Hôtel-Dieu, F-63001 Clermont-Ferrand, France; Univ Clermont1, UFR d'Odontologie, EA 4847, F-63000 Clermont-Ferrand, France.