Sixty-four samples of four types of composite resin were uniformly finished to a 600-grit smoothness and subjected to uniform manual manipulation (curette), ultrasonic manipulation, and sonic manipulation to simulate dental scaling to determine the degree of surface alteration of the resin resulting from each type of instrumentation. All specimens were hydrated and weighed before and after being subjected to instrumentation. Control samples were retained for each type of composite resin and were finished but not instrumented. Measurements of surface roughness were made before and after instrumentation using a Surfindicator and samples were subjectively viewed and photographed under scanning electron microscope. Statistical analyses were done to determine the significance of surface alterations by the three methods of simulated dental scaling. All three types of manipulation altered the composite resin surfaces significantly but the hand curettes yielded the most significant alterations.