title: Hydroxyl radical release from dental resins: electron paramagnetic resonance evidence.
abstract: It is well known that polymeric free radicals remain trapped inside dental resins for a long time after photopolymerization. Moreover, although these high molecular mass compounds have very limited mobility, there is evidence to suggest that they disappear progressively over time. The purpose of this study was to provide new experimental data to help understand this phenomenon. To determine whether low molecular mass free radicals are released by dental composites stored in hydrophilic media, we used electron paramagnetic resonance spectroscopy to perform spin-trapping experiments on experimental and commercial samples stored in ethanol. Under these conditions, ethoxy radicals were produced. Further experiments demonstrated that (1) hydroxyl radicals were released from the methacrylated resin and (2) they reacted with ethanol molecules to produce "secondary" ethoxy free radicals. In addition to the well-known monomer toxicity of methacrylated resins, we may have identified a new source of concern for these biomaterials.
authors.affiliation: School of Dental Medicine and Stomatology, Université catholique de Louvain, Avenue Hippocrate 10/5721, Brussels B-1200, Belgium.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Lamblin
authors.forename: Julian
authors.initials: J
authors.lastname: Leprince
authors.forename: Jacques
authors.initials: J
authors.lastname: Devaux
authors.forename: Michèle
authors.initials: M
authors.lastname: Mestdagh
authors.forename: Bernard
authors.initials: B
authors.lastname: Gallez
authors.forename: Gaëtane
authors.initials: G
authors.lastname: Leloup
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D000431:Ethanol / Q000737:chemistry; D016166:Free Radical Scavengers / Q000737:chemistry; D005609:Free Radicals / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry*; D007700:Kinetics; D011758:Pyrroles / Q000737:chemistry; D012117:Resins, Synthetic / Q000737:chemistry*; D019097:Spin Trapping; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: C510912:(diethoxyphosphoryl)-5-methylpyrroline N-oxide; C406273:2-ethoxycarbonyl-2-methyl-3,4-dihydro-2H-pyrrole-1-oxide; D016166:Free Radical Scavengers; D005609:Free Radicals; D011758:Pyrroles; D012117:Resins, Synthetic; D014867:Water; D017665:Hydroxyl Radical; D000431:Ethanol