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 degrees C 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.