Principles

Very few clinicians would contest the notion of silver amalgam being a popular and successful restorative material. In recent years, however, particularly in light of the Minamata Treaty 2013 (which among several other objectives aims to phase down the use of dental amalgam), there has been an international shift concerning the placement of silver amalgam restorations, with countries such as Norway imposing a complete ban on the prescription of amalgam-based restorations by 2011 (primarily on account of environmental concerns).

In Australia, a government report published by a working group for the NHMRC (National Health and Medical Research Council) described a reduction in the provision of dental amalgam restorations by private general dental practitioners, from 57.9% in 1983–84 to 28.0% in 1997–98 (when considering the total number of dental restorations placed, inclusive of indirect restorations), thereby representing a reduction by almost 50%.¹

This trend is most likely to be accounted for by the implementation of a more minimally invasive philosophy by dental practitioners, with a concomitant increase in the number of resin composite restorations, which doubled over the same time periods.

Directly bonded posterior resin composite restorations have indeed become increasingly popular for the conservative and aesthetic management of small to medium-sized cavities in posterior teeth. They may also potentially provide a means of strengthening and conserving the remaining tooth substrate in the longer term. However, direct resin restorations (of both the anterior and posterior varieties) are, as with most other dental materials, prone to failure or fracture. Many of the problems arise from inherent flaws relating to the physico-chemical properties of resin composite, such as polymerisation shrinkage, increased surface wear and bulk fracture.

Nevertheless, resin composite materials do offer the potential for intra-oral repair (which other materials such as metal alloys do not). Thus, in the case of a failed resin composite restoration, it has been advocated that the latter should be evaluated for possible repair instead of complete replacement and re-making, on the grounds of the need for reduced intervention.²

There are a number of scenarios where repair or refurbishment of an existing resin composite restoration may be considered a suitable option:

• Loss of anatomical contour
• Marginal faults
• Surface roughness from wear
• Secondary caries when it is readily accessible
• Staining and reduced lustre.