In animal experiments guinea pigs were subjected three times weekly for 4 weeks to cleaning with a plane multitufted or a toothed "space tufted" toothbrush for 20 seconds by a standardised method comparing opposing quadrants on each side. Scan electronmicroscopic evaluation of the tissue exfoliation from the area of attached gum before cleaning, after 2 and 4 weeks, shows that localised though different epithelial lesions occur with both tooth brushes. The lesions reach into the submucosa with the toothed type brush. Influence on the epithelium in the sense of normalising keratinisation after tooth brush massage could not be confirmed.