Evaluation of a Tensile Test for Direct Filling Resins

¹ University of Michigan, School of Dentistry, Ann Arbor, Michigan 48104

A test method intended to measure the bond strengths of filling resin-dental substrate combinations under tensile loading has been evaluated and modified so that it is capable of statistically ranking the bonding abilities of commercially available dental resins. The test method is simple and inexpensive with demonstrated reliability. It should fill a need that currently exists for a test method to evaluate adhesive dental resins.

Dental substrates that served as model adherents were bovine enamel and bovine dentin. The sensitivity of the test proved adequate in discriminating among the bonding abilities of the five typical commercial resins to both substrates when they had been freshly surfaced and also when they had been etched with citric acid. Adhesion to enamel increased, on the average, over 200% after a citric acid etch. Adhesion to freshly surfaced dentin, which was minimal or nonexistent except for the carbohydrate cement, increased slightly after a citric acid etch.

The rank order of bond strengths was different for each substrate and was further altered by etching the surface of each substrate so that no single resin performed best under all conditions.