title: Apparent conversion of adhesive resin in the hybrid layer, Part II: In situ studies of the resin-dentin bond.
abstract: Penetration and conversion of adhesives into the hybrid layer (HL) is important to the quality and longevity of the adhesive resin (AR)-dentin bond. In this study, a methodology is developed to examine the degree of conversion and relative HEMA concentration with respect to Bis-GMA using Raman spectroscopy. This methodology will be used in the future reports related to this topic. Conversion in the AR of water-stored resin-dentin samples (84% +/- 3%) agreed well with that measured in commercial adhesive (Comm Adh) resin samples after 24-h water storage (80% +/- 2% from Part 1) and was significantly higher than Comm Adh without water storage (58% +/- 3% from Part 1) (p = 0.0005). Adhesive conversion was not significantly different (p = 0.5036) through the middle of the HL, with a mean of 83% +/- 6%. HEMA mole fraction, relative to Bis-GMA, was significantly higher (p = 0.0028) in the top half of the HL (0.67 +/- 0.03), when compared to HEMA in the AR (0.60 +/- 0.01). HEMA and EDMAB were identified through GC/MS as leachable components in the aqueous 24-h storage media. The effect of this elution explains the change in conversion measurements observed between dry and water-stored conditions, which is more appropriately described as the "apparent" conversion.
authors.affiliation: Department of Chemical and Biochemical Engineering, University of Iowa, Iowa City, Iowa 52242, USA.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zou
authors.forename: Julie L P
authors.initials: JL
authors.lastname: Jessop
authors.forename: Steven R
authors.initials: SR
authors.lastname: Armstrong
mesh_terms: D000269:Adhesives / Q000737:chemistry*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D011108:Polymers / Q000737:chemistry; D012117:Resins, Synthetic / Q000737:chemistry*; D013059:Spectrum Analysis, Raman
chemical_list: D000269:Adhesives; D017220:Dentin-Bonding Agents; D011108:Polymers; D012117:Resins, Synthetic