Effect of surface conditioning on the abrasion rate of dental composites.

Seven dental composites were conditioned prior to wear testing in a three body abrasion machine. The physical conditioning comprised thermal cycling or storage in water for equivalent times. Chemical conditioning was with 75 per cent ethanol or n-heptane. The results indicated that specimens conditioned by 50,000 thermal cycles had an increased surface abrasion rate. With chemical conditioning, 75 per cent ethanol increased the abrasion rate in a number of materials. Both of the latter treatments are clinically unrealistic. As the specimens in other groups were not statistically separable, the results do not support the concept that surface degradation in the mouth is a major variable for three body abrasion.