[The influence of brushing methods on wedge-shaped defects].

By experimentally brushing 20 teeth vertically to the tooth axis under a pressure of 2 N only lesions in cementum or dentine could be obtained. There was no case in which enamel was damaged by our brushing experiments. Therefore, defects appearing clinically cannot be explained by wrong tooth brushing techniques. There were several parallel lesions (similar to a saw blade) to be found as well as confluent hard tissue losses. Both indicate the direction of the movement of the tooth brush. The smallest defect to be measured in coronal-apical direction was 2.25 mm, the biggest 6.7 mm. The depth of the defects ranged front 239.9 microns to 493.2 microns. A correlation between Vicker's hardness and substance abrasion could not be proved, nor was the clinical appearance of wedge-shaped defects to be achieved by means of our experimental device. The formation of enamel defects cannot be explained by mere mechanical abrasion due to tooth brushing. In our opinions the formation of wedge-shaped defects implies a multicausal process.