The effect of toothbrushing, using tap water, pumice, or dentifrice, on five resins—-two microfiller resins, one composite resin with both large and microfiller particles, one composite resin introduced as a filling material for posterior teeth, and one conventional composite resin—-was studied by scanning electron microscopy. Brushing with water had almost no effect on the unfinished specimens. When the unfinished and finished specimens of the large filler-containing materials were brushed with toothpaste or pumice, rough surface characteristics were obtained. After the finishing and toothbrushing procedures only one of the microfiller materials showed very smooth surface characteristics. The microfiller materials may be finished with successively finer devices to smooth surfaces that will stay smooth after toothbrushing, whereas finishing the large filler-containing resin materials does not lead to a lasting smooth surface.