The use of dentinal etching with endodontic bleaching procedures

The removal of the smear layer from dentinal surfaces has been shown to increase significantly the permeability of dentin in both vital and endodontically treated teeth by opening the orifices of the dentinal tubules. This knowledge has led to the practice of acid etching the intracoronal dentin of endodontically treated teeth prior to nonvital bleaching procedures in order to increase the speed and effectiveness of the bleach. In this study extracted human teeth, which had been stained in vitro, were used to compare the effects of dentinal etching of the pulp chambers with no acid etching in conjunction with "walking bleach" procedures. In one experimental group, the pulp chambers were acid etched with 50% phosphoric acid for 1 min to remove the smear layer prior to insertion of the 30% hydrogen peroxide/sodium perborate bleaching agents. The second group had the same chamber preparation except the acid etching was deleted. Evaluators were unable to distinguish a significant difference between the effectiveness of the bleaching procedures in the two experimental groups.