In vitro plaque formation on commonly used dental materials.

An in vitro method has been developed for the study of microbial plaque formation on commonly used dental restorative materials. Standard samples of the materials to be studied are suspended in a complex culture medium inoculated with a bacterial suspension. The samples are transferred daily into freshly inoculated medium for a total of 4 days. The resultant microbial plaques are then graded, weighed and assessed for a number of colony forming units (viable count). In this preliminary experiment samples of amalgam, composite cement, gold and porcelain were examined. Significantly less plaque was formed on amalgam than on any of the other materials.