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Assessment by nano-indentation of the hardness and elasticity of the resin-dentin bonding area.

Authors
  • Van Meerbeek, B
  • Willems, G
  • Celis, J P
  • Roos, J R
  • Braem, M
  • Lambrechts, P
  • Vanherle, G
Type
Published Article
Journal
Journal of dental research
Publication Date
Oct 01, 1993
Volume
72
Issue
10
Pages
1434–1442
Identifiers
PMID: 8408887
Source
Medline
License
Unknown

Abstract

The hardness and Young's modulus of the successive layers across a resin-dentin bonding area were determined by nano-indentation for four commercially-available dentin adhesive systems, of which two were also applied with a different conditioning agent. With a computer-controlled nano-indentation technique, minute triangular indentations were made within a small area of a few micrometers' diameter at a load of a few milli-Newtons. The load and displacement of the indenter were continuously monitored during the loading-unloading sequence, so hardness and Young's modulus could be computed as a function of the indenter geometry and the applied load. The hardness of the resin-dentin interdiffusion zone was significantly lower than that of unaltered dentin. A gradient of moduli of elasticity was observed from the rather stiff dentin over a more elastic resin-dentin interdiffusion zone and adhesive resin layer to the restorative composite. That gradient was more substantial in those systems that produced relatively thick adhesive resin layers or supplementally provided a filled low-viscosity resin as an intermediate layer between the adhesive resin and the bulk restorative composite. Such an elastic bonding area might have a strain capacity sufficient to relieve stresses between the shrinking composite restoration and the rigid dentin substrate, thereby improving the conservation of the dentin bond and, as a consequence, the marginal integrity and retention of the restoration.

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