title: Electrical properties of resin monomers used in restorative dentistry.
abstract: OBJECTIVE
  The application of an electric field has been shown to positively influence the impregnation of the resin monomers currently used in dentin bonding systems during hybrid layer formation. This study presents an experimental characterization of the electrical properties of these monomers with the aim of both correlating them to their chemical structures and seeking an insight into the mechanisms of the monomer migration under an applied electric field.
  
  
  METHODS
  Some common monomers examined were TEGDMA (triethyleneglycoldimethacrylate), HEMA (2-hydroxyethyl methacrylate), UDMA (urethane dimethacrylate), 2-MP (bis[2-(methacryloyloxy)ethyl] phosphate, TCDM di(hydroxyethyl methacrylate) ester of 5-(2,5-dioxotetrahydrofurfuryl)-3-methyl-3-cyclohexenyl-1,2-dicarboxylic anhydride) and Bis-GMA [2,2-bis(4-2-hydroxy-3-methacryloyloxypropoxyphenyl)propane]. A customized cell produced for the measurement of the electrical properties of monomers was manufactured and electrical conductivity and permittivity of resin monomers were measured.
  
  
  RESULTS
  The permittivity of the tested monomers is largely affected by electrical frequency. The large values of permittivity and dielectric losses observed as frequency decreased, indicate a dominant effect of ionic polarization, particularly evident in materials showing the highest conductivity. Permittivity and conductivity of the tested monomers showed a similar behavior, i.e. materials with the lowest permittivity also show small values of conductivity and vice versa.
  
  
  CONCLUSIONS
  The results of the present study revealed a good correlation between electrical properties and Hoy solubility parameters and, in particular, the higher the polar contribution (polar forces plus hydrogen bonding) the higher the permittivity and conductivity. The most relevant outcome of this study is that the electrophoretic mechanism prevails on the electroendoosmotic effect in determining the monomer migration under the application of electric fields.
authors: Department of Electrical Engineering, University of Bologna, Italy.
authors: Marco
authors: M
authors: Breschi
authors: Davide
authors: D
authors: Fabiani
authors: Leonardo
authors: L
authors: Sandrolini
authors: Martino
authors: M
authors: Colonna
authors: Laura
authors: L
authors: Sisti
authors: Micaela
authors: M
authors: Vannini
authors: Annalisa
authors: A
authors: Mazzoni
authors: Alessandra
authors: A
authors: Ruggeri
authors: David H
authors: DH
authors: Pashley
authors: Lorenzo
authors: L
authors: Breschi
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding / Q000379:methods*; D004553:Electric Conductivity; D008422:Materials Testing / Q000295:instrumentation / Q000379:methods*; D012995:Solubility
chemical_list: D003188:Composite Resins