Dentin permeability: self-etching and one-bottle dentin bonding systems.
STATEMENT OF PROBLEM: There are many bonding systems available, with or without a prior acid etch. The mechanisms differ from system to system. Therefore it is important that the clinician know which are the most effective and which provide the best seal. PURPOSE: This study measured the infiltration of physiological saline solution across dentin after application of self-etching or 1-bottle dentin bonding systems. MATERIALS AND METHODS: Thirty-six extracted noncarious human third molars from patients 18 to 25 years old were used for this study. Dentin disks were cut from crown segments parallel to the occlusal surface at the incisal portion of the pulp cavity. The 36 disks, each 1 mm thick, were divided into 6 groups (n=6 per group), each of which received one of the following dentin bonding systems: Optibond Solo Plus and Excite, which have ethanol as the solvent; Prime & Bond NT, which has acetone as the solvent; Single Bond, which has a mixed solvent; and Clearfil SE Bond or Prompt L-Pop, both self-etching systems The hydraulic conductance, the volume of fluid transported across a known area of surface (0.28 cm(2)) per unit time under a unit pressure gradient (200 cm H(2)O), was analyzed for the self-etching and 1-bottle dentin bonding systems with the Flodec apparatus. Both sides of each specimen were etched with 36% phosphoric acid for 30 seconds. Measurements were made every 30 seconds for 15 minutes. The initial measurement served as the reference value for each specimen. The measurements were repeated when a smear layer had been formed and, finally, after one of the 6 bonding systems had been applied. The data were analyzed by use of analysis of variance and a posteriori tests (Fischer's PLSD, Duncan's new multiple range) with alpha=.05. RESULTS: The greatest mean reduction (40%, P<.05) in penetration was observed with the 4 products with conventional etching: Optibond Solo Plus, Single Bond, Excite, and Prime & Bond NT. The self-etching products were associated with reductions of 36% (Clearfil SE Bond) and 16% (Prompt L Pop). Standard deviations were high, 50% of the mean value, except for the Single Bond group (-42 +/- 13) and Prime & Bond NT (-41 +/- 14). CONCLUSION: Within the limitations of this study, the 4 bonding systems tested with a phosphoric acid before etching provided a greater decrease in dentin permeability than the 2 self-etching systems. The difference in permeability decrease was significant for Prompt L-Pop but not for Clearfil SE Bond.