SUMMARY
Objectives: This study assessed the nanohardness (NH) and Young's modulus (YM) of resindentin bonding components formed by an ethanol/water-based (Adper Single Bond Plus [SBP]) and an acetone-based system (One Step Plus [OSP]) under different moisture conditions and application methods.Material and Methods: On 24 human molars, a flat, superficial dentin surface was exposed by wet abrasion. After acid-etching, two coats of SBP or OSP adhesive were applied on either a dry or rewetted dentin surface under vigorous rubbing action or inactive application. After polymerization of the adhesives (600 mW/cm 2 /20 seconds), composite buildups were constructed incrementally and the specimens were stored in water (37°C/24 hours). They were cross-sectioned perpendicular to the resin-dentin interface to obtain 1.5 mm-thick slices that were embedded and polished before the test. Nano-indentations
C Higashi • MD Michel • A Reis AD Loguercio • OMM Gomes • JC Gomes
Clinical RelevanceThe vigorous rubbing action of acetone and ethanol/water-based adhesives into dry demineralized dentin resulted in high nanohardness and Young's modulus in the hybrid layer, and moisture increased the nanohardness and Young's modulus of Adper Single Bond Plus in the adhesive layer. Results: When the dentin was kept wet, the mode of application did not affect the studied properties within the hybrid layer. On the other hand, the vigorous application mode increased the NH and YM of both adhesives applied in airdried dentin. In the adhesive layer, the highest NH and YM were observed only for SBP, especially when applied in wet dentin under vigorous action.Conclusion: It was concluded that: 1) the vigorous application of both adhesives in dry dentin resulted in high nanohardness and Young's modulus values in the hybrid layer and 2) in the adhesive layer, the moisture associated with the vigorous application mode increased the nanohardness and Young's modulus values of Adper Single Bond Plus.