Secondary Caries

Secondary caries, the lesion at the margin of a restoration, has been widely considered as the most important and common reason for restoration replacement, regardless of the restorative material type [Collins et al., 1998; Dahl and Eriksen, 1978; Deligeorgi et al., 2001; Friedl et al., 1995; Mjör, 2005; Mjör and Toffenetti, 2000;]. As it develops after the initial caries has been removed and replaced by a restoration, 'secondary caries', which is often referred to as 'recurrent caries' by practitioners in North America, is used more commonly in Europe[Mjör, 2005]. The Fédération Dentaire Internationale defined secondary caries as a ‘positively diagnosed carious lesion, which occurs at the margins of an existing restoration’ [Fédération Dentaire Internationale, 1962]. Then two kinds of lesion may exist adjacent to the restorations: secondary caries and residual caries (remaining caries). The latter one is residual demineralized tissue left, due to the failure of eliminating all infected dentine or/and enamel during the cavity preparation. Therefore it is very difficult for clinicians to make an accurate diagnosis of secondary caries and provide a clear terminology. Nowadays it is generally acknowledged that secondary caries or recurrent caries is a primary carious lesion of tooth at the margin of an existing restoration, which occurs after the restoration has been used for some time [Mjör and Toffenetti, 2000].