Materials to restore tooth defects in patients are subjected to wear from the first day. Excessive wear compromises the function of the restored teeth. As wear measurements in-vivo are complicated and time-consuming, different wear simulation devices and methods have been developed. They are meant to simulate processes that occur in the mouth during mastication. A round robin test that evaluated the wear of 10 materials with five simulation methods showed that the results were not comparable. When correlating material properties to the wear results of 24 composite resins with a specific wear method, some physical parameters could be identified and incorporated into a wear formula to predict wear for this method. The wear method should not only efficiently generate reproducible data but the data should also correlate with clinical wear rates. A huge database on clinical wear of different composite resins and amalgam was used to compare wear with six laboratory methods. Only one method showed an acceptable correlation with clinical situation. The clinical wear data revealed that to date no composite resin is as wear resistant as amalgam.