In this study, scaling alone resulted in endotoxin values considerably greater than the values for healthy root surfaces. However, the root-planed Samples contained only about 1 ng more of endotoxin than did the healthy root surfaces. This small difference can be accounted for by the presence of small flecks of calculus left after root planing. Considering that out of a total sample size of 48 surfaces there was only 1 ng difference in the amount of endotoxin between planed teeth and uninvolved teeth, the basic conclusion must be that root planing, as performed in this study, was able to render diseased root surfaces approximately as free of detectable endotoxin as were uninvolved, healthy root surfaces of unerupted teeth.