Composites and glass ionomers have not been extensively tested in clinical trials for biological safety. Most clinical evaluations have looked at other factors, such as retention, wear, or color. The primary evaluation criterion used in clinical trials is post-operative sensitivity. Sensitivity does not seem to have any correlation to pulpal inflammation. Inflammation can be the result of mechanical, thermal, chemical, and bacterial insults. It is complicated for individual contributions to be separated in short-term studies. General usage of these materials over about 20 years indicates a high benefit-to-risk ratio. Despite some complaints of sensitivity with some glass-ionomer compositions, both composites and glass ionomers are relatively trouble-free. There is no evidence of short-term or long-term risk. Toxicological studies have focused almost exclusively on pulpal reactions. Systemic reactions have not been closely examined, although there is no suspicion of any problems after virtually billions of procedures in the United States. New glass-ionomer cements are similar to contemporary composite formulations. Continued development of these materials may ultimately produce an amalgam replacement material that is economically and philosophically desirable to general dentists.