Implications for dental practice. Over the past few decades, the number of patients who have requested a “mercury-free” restorative material that is more esthetic than amalgam has increased. Although resin-based composite fulfills these criteria, its longevity as posterior restoration seems to be inferior compared with that of amalgam. This systematic review suggests that posterior resin-based composite may have a higher risk of experiencing failure and secondary caries compared with amalgam. The analysis by the reviewers did not provide information about restoration failure from a time-to-event outcome perspective (survival analysis). Such information would be of value for clinicians and patients, as it would facilitate decision making. Patients should be informed of this increased risk when given the options of different restorative materials, but at the same time, keeping in mind that the physical properties of composite materials are being constantly improved and when placed with great care are viable alternatives to amalgam.   http://jada.ada.org/article/S0002-8177(16)30713-9/fulltext