The authors have developed a set of four modified sonic scaler inserts with variuosly shaped shafts and diamon-coated budded inserts. The inserts are specially designed for the furcation area since instruments used hitherto have not been successful in completely preventing slow continuous periodontal breakdown in multirooted teeth. To improve understanding of their clinical effectiveness, instrumentation of dentin samples was done with a curette as well as conventional and modified sonic scaler inserts under standardized conditions. The results showed that significantly greater amounts of tooth substance were removed with the diamond-coated airscaler tips than with the conventional tip. The depth of substance removal was comparable to that obtained with hand instruments and increased with application force. Although differences in surface texture were found among the different modes of scaling, it remains to be dtermined whether they are of clinical significance.