A Method of Testing for Marginal Leakage of Dental Restorations with Bacteria

¹ Division of Microbiology and Department of Dental Materials, Marquette University School of Dentistry, Milwaukee, Wisconsin

The penetration of micro-organisms between the margins of amalgam restorations, zinc phosphate cement, and silicate cement restorations was studied by employing Serratia marcescens as the testing agent.

It was concluded that under the experimental conditions employed, approximately 55 per cent of the amalgam restorations placed in intact teeth allowed bacteria to pass between the margin of the restoration and the cavity wall. A thick mix of zinc phosphate cement used in this study showed less microleakage (10 per cent) than a silicate cement (33 per cent) which had a powder/liquid ratio according to the manufacturer's directions.

Microleakage apparently occurred as a result of penetration of the test bacteria between the margins of the restorations and the walls of the cavity preparations.

It was concluded that the method herein described is suitable for testing microleakage of dental restorations. Additional work is contemplated to establish the effect of manipulative variables, such as the effect of cavity liners and of various cutting techniques.