Although improvements in wear resistance have accompanied the development of newer materials, the routine use of composite resins in permanent posterior teeth cannot be justified. Clinical studies have not yet proved the long-term wear resistance of these materials. However, they may be used if case selection and material selection are kept within certain guidelines. In terms of case selection, a composite resin might be used in areas of esthetic concern, or where minimal cavity preparation is possible. Resins might also be used in areas of low functional stress, and in premolars instead of molars. In selecting a material, the conventional resins should never be used for posterior teeth. Instead, a material with smaller, softer filler particles should be used. Also, light-cured materials are preferred to the self-cured types. Long-term clinical evaluation of the posterior composite resins is required before they can be accepted as a substitute for amalgam. If the problem of wear cannot be eliminated, but only reduced, then the effects of wear in terms of occlusal stability and function must be determined.