Dimensional changes and ultimate tensile strengths of wet decalcified dentin applied with one-bottle adhesives

Objectives: The objectives of this study were to test the null hypothesis that no dimensional changes in wet decalcified dentin matrices will occur during the application of one-bottle adhesives, and to evaluate the ultimate tensile strengths (UTS) of resin-infiltrated dentin matrices using the microtensile test. Methods: Dentin disks 0.2 mm thick were prepared from mid-coronal dentin of human unerupted third molars. They were completely decalcified in 0.5 M EDTA (pH 7.4) for 5 days at 25 degreesC and then placed in the bottom of an aluminum well to permit use of the LVDT portion of a thermal mechanical analyzer. Changes in matrix height in response to the application of Single Bond, One-Step or Prime & Bond NT were measured along with the UTS of resin-infiltrated specimens that were compared using a one-way ANOVA and Fisher's PLSD test. Results: All one-bottle adhesives produced a gradual, progressive shrinkage of the decalcified matrix of 26-33%. The shrinkage produced by Single Bond was significantly greater (p < 0.05) than that produced by the other adhesives. The UTS of One-Step was significantly higher (<0.05) than that of Prime & Bond NT (42.0 +/- 13.6 vs 29.7 +/- 1.9 MPa, respectively), with Single Bond producing intermediate UTS (34.3 +/- 7.4 MPa). Significance: If the durability of resin-dentin bonds depends upon the size of interfibrillar spaces for both diffusion channels and resin uptake, then adhesive formulations should be designed to minimize matrix shrinkage during resin infiltration. (C) 2002 Academy of Dental Materials. Published by Elsevier Science Ltd. All rights reserved.