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Interfacial chemistry of moisture‐aged class II composite restorations
Author(s) -
Spencer Paulette,
Wang Yong,
Bohaty Brenda
Publication year - 2006
Publication title -
journal of biomedical materials research part b: applied biomaterials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.665
H-Index - 108
eISSN - 1552-4981
pISSN - 1552-4973
DOI - 10.1002/jbm.b.30434
Subject(s) - dentin , adhesive , demineralization , composite number , molar , materials science , aqueous solution , dentistry , gingival margin , composite material , bond strength , dental cement , chemistry , enamel paint , organic chemistry , medicine , layer (electronics)
Under in vivo conditions, the adhesive/dentin bond at the gingival margin of class II composite restorations can be the first defense against substances that may penetrate and ultimately undermine the composite restoration. Deterioration of this bond during aqueous aging is an area of intense investigation, but to date, the majority of our techniques have provided only an indirect assessment of the degrading components. The purpose of this study was to analyze the in situ molecular structure of adhesive/dentin interfaces in class II composite restorations, following aging in aqueous solutions. Class II preparations were cut from 12 unerupted human third molars, with a water‐cooled, high‐speed, dental handpiece. The prepared teeth were randomly selected for restoration with single bond (SB) and Z100 (3M). Teeth were restored, as per the manufacturer's directions, under environmental conditions that simulated humidity and temperature characteristics of the oral cavity. Restored teeth were kept in sterile Delbecco's phosphate saline for 48 h or 90 days. The samples were sectioned occlusogingivally and micro‐Raman spectra were acquired at ∼1.5 μm spatial resolution across the composite/adhesive/dentin interfaces at the gingival margins. Samples were wet throughout spectral acquisition. The relative intensity of bands associated with the adhesive in the interfacial region decreased dramatically after aqueous storage. This decrease in concert with the similar depth of dentin demineralization provides direct spectroscopic evidence of leaching of adhesive monomer from the interface during the 90 days of storage. SB adhesive infiltrated 4–5 μm of 12‐μm demineralized dentin at the gingival margin. After 90 days of aqueous storage, SB adhesive infiltration was reduced to ∼2 μm, leaving ∼10 μm of demineralized dentin collagen exposed at the gingival margin. The unprotected collagen at the gingival margin of the aged class II composite restorations was disorganized, suggesting hydrolysis of the collagen, with 90 days of aqueous storage. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006