10 as demonstrated in analyses of the patterns of provision of dental restorations within National Health Service dental services in the UK and in large North American studies.For example, within a cohort of over 300,000 patients in 2002, Bogacki et al noted that the probability of survival of both posterior amalgam and resin composite restorations was in excess of 90% over 5 years, but that this survival rate dropped to 60% (for both types of restoration) when patients changed dentist. A more recent dental practice-based research study, involving 197 clinicians in the USA and Scandinavian countries, and close to 10,000 restorations, indicated that when considering treatment options for restorations with localized defects, in over 75% of cases the practitioners choose replacement rather than repair.The same study confirmed that decisions to replace restorations with limited defects are particularly common for restorations not placed by the evaluating practitioner.