Reasons for replacement of Class II amalgam restorations in private practice.

In a series of postgraduate courses in Cariology for dentists in the period 1980-84, a total of 102 private practitioners participated in a study of the reasons for replacing amalgam restorations. Twelve reasons were specified on a form and the dentist was asked to mark one or more of them for each filling replaced. The total number of fillings evaluated was 2033. In 87.9% of the restorations only one reason was given for the replacement; two, three, four and five reasons were registered in 10.5, 1.1, 0.4 and 0.1%, respectively. The six most frequent reasons were: "secondary caries" (34.0%), "fracture of the filling" (15.5%), "primary caries" (12.1%), "fracture of the tooth" (10.2%), "marginal ditching" (7.2%), and "caries under the filling" (5.6%). The restorations replaced for a combination of two reasons (N = 213) were studied separately. The three most frequent combinations were: "secondary caries + fracture of the filling" (17.8%), "secondary caries + marginal ditching" (14.1%), and "secondary caries + caries under the filling" (11.3%). - Thus, the main conclusion from this study is that approximately half of the replacements of class II amalgam restorations were occasioned by caries disease.