Dental Materials
Volume 22, Issue 10 , Pages 963-972, October 2006

Polymerization efficacy of simplified adhesive systems studied by NMR and MRI techniques

  • T.G. Nunes

      Affiliations

    • Departamento de Engenharia de Materiais/IST, Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal
    • Corresponding Author InformationCorresponding author. Tel.: +351 21 8418103; fax: +351 21 8418101.
    • ,
  • F.C.P. Garcia

      Affiliations

    • University of São Paulo, Bauru School of Dentistry, Brazil
    • ,
  • R. Osorio

      Affiliations

    • Departamento de Estomatología, Universidad de Granada, Spain
    • ,
  • R. Carvalho

      Affiliations

    • University of São Paulo, Bauru School of Dentistry, Brazil
    • ,
  • M. Toledano

      Affiliations

    • Departamento de Estomatología, Universidad de Granada, Spain

Received 8 June 2005; received in revised form 19 October 2005; accepted 27 October 2005.

Abstract 

Objective

To ascertain the efficacy of polymerization of self-etching dental adhesives in different solvent evaporation conditions.

Material and methods

Four self-etching adhesive systems were studied. Two of them are classified as mild two-step self-etching adhesives (Clearfil SE Bond, Protect Bond) and the other two are strong one-step systems (Xeno III, ADP-Prompt-L-Pop). The influence of temperature and duration of the air-drying period on photo-polymerization was followed by: gravimetry, 1H solid-state NMR spectroscopy and stray-field MRI. The evolution of proton magnetization with irradiation time was recorded and correlated with volumetric polymerization shrinkage and extent of reaction; evaporation and hardening effects were identified.

Results

Main variables determining water-solvent evaporation of the tested adhesives are: (1) water/HEMA relative concentration, (2) presence of photoinitiator compounds in the primer (SEB) and (3) presence of ethanol (XENO). SEB shows the highest extent of photo-polymerization of the tested adhesives. The lowest volumetric contraction was obtained for APLP and XENO and the attempt to remove the solvents did not increase the extent of polymerization significantly.

Conclusions

Temperature increase following photo-polymerization reaction is dominant towards the effect of the drying step for solvent evaporation in self-etching systems. Attempts to remove the solvents did not increase the extent of polymerization, so other problems are impairing the polymerization of one-step adhesives.

Clinical significance

The use of tested one-step adhesives is discouraged as the attained low extent of polymerization may lead to low bond strength, high susceptibility to degradation and also will favor a continuing etching effect on the underlying dentin.

Keywords: Dentin adhesive systems, Self-etching, Photo-polymerization, HEMA, Solvent evaporation, Nuclear magnetic resonance, Stray-field magnetic resonance imaging

To access this article, please choose from the options below

Login to an existing account or Register a new account.

  • Purchase this article for 31.50 USD (You must login/register to purchase this article)

    Online access for 24 hours. The PDF version can be downloaded as your permanent record.

  • Subscribe to this title

    Get unlimited online access to this article and all other articles in this title 24/7 for one year.

  • Claim access now

    For current subscribers with Society Membership or Account Number.

  • Visit SciVerse ScienceDirect to see if you have access via your institution.
 

PII: S0109-5641(05)00312-X

doi:10.1016/j.dental.2005.10.008

Dental Materials
Volume 22, Issue 10 , Pages 963-972, October 2006

Article Tools

* Image Usage & Resolution