Consumers spent $10 billion on restorative dental treatment in 1979. Little information is available regarding the life expectancy of these restorations or what proportion of these restorations replaces previous ones. A critical literature review was presented, covering all available longevity data of posterior restorations. Necessary methodologic standards for evaluation of the studies were outlined and used in the review. The lack of these critical variables--patient selection, missing follow-up data, and judgment criteria for determining need for replacement or failure (or both)--minimized the usefulness of the results. Study results are generalizable only to similar patient populations and not all patients. Much more controlled research needs to be done.