The effect of NaOCl dentin treatment on nanoleakage formation

The term "nanoleakage" has been introduced to explain a penetration pathway within hybrid layers of the dentin-composite junction in the absence of ga p formation. This phenomenon is argued in the Literature to be a risk facto r for the quality of the dentin bonding. NaOCl is a well-known agent used t o remove collagen layers that are exposed after acid etching. The purpose o f this study was to determine the influence of an NaOCl treatment of dentin to the formation of nanoleakage. Class V cavities were prepared in 40 huma n molars with the cervical margins located in dentin. After etching with ph osphoric acid, 20 samples were treated with 10% NaOCl for 60 s, and 20 samp les were used as control. Composite restorations were placed using two diff erent bonding systems. The specimen were exposed in silver nitrate solution and then in developer. After embedding, the teeth were sectioned, dried, c oated with gold, and analyzed by SEM. For all the specimen in the control g roup, backscatter images indicated a silver penetration within the hybrid l ayer. There was no penetration of silver detectable in the teeth that were treated with NaOCl. We conclude that the removal of the collagen layer by u sing NaOCl avoids the formation of nanoleakages with the materials tested. (C) 2001 John Wiley & Sons, Inc.