The trimming of composite resin restorations encompasses gross finishing, contouring, fine finishing, and polishing. A series of aluminum oxide-coated flexible disks have been marketed and are suitable for that purpose. However, their use is confined to directly accessible convex surfaces. For precise finishing of small delineated areas, and for concave and occlusal surfaces, rigid rotary instruments are necessary. The currently used stones and tungsten carbide burs are ineffective with microfilled composite systems. Thus, a series of finishing burs coated with 40- and 15-microns diamond chips were evaluated because of the superior grinding effectiveness as compared with existing instruments. Surface roughness measurements, and qualitative and quantitative SEM evaluations, indicate that these fine and superfine diamond finishing burs produce surfaces on composite resins as smooth as tungsten carbide burs and stones. At the same time, they cause less surface and subsurface damage or marginal fractures on composite resin restorations. The three-year clinical experience is generally favorable. Further quantitative clinical studies are warranted.