The fluid-filled gap under amalgam and resin composite restorations.

This article discusses the factors involved in the formation of marginal gaps between amalgam or resin composite restorative materials and cavity walls. The fluid that penetrates the microspace from the oral cavity and from the dentinal tubules is followed by bacterial invasion. This process can lead to secondary caries and irritation of the dentin/pulp complex. The bacterial growth is controlled by effective sealing at the tooth/restoration interface, partial obliteration of the gap, accumulation of solids at the cavosurface margins of the restorations, and by antibacterial linings.