Microleakage channels: scanning electron microscopic observation.

Resin casts were made of microleakage channels surrounding amalgam restorations in vitro. After demineralizing the tooth and digesting the remaining organic matrix, the amalgam restorations covered with the resin casts were examined using a scanning electron microscope. An extensive reticular network of channels was observed on restorations which were placed in cavities lined by smear layers. Amalgam restorations placed in cavities devoid of smear layers exhibited fewer microleakage channels.