Journal of Dental Research, Vol 69, 31-35, Copyright © 1990 by International & American Associations for Dental Research Online Journals
Fracture-mechanics parameters of the composite-enamel bond
R. de Groot, H. C. van Elst and M. C. Peters
Department of Cariology and Endodontology, School of Dentistry, University of Nijmegen, The Netherlands.
In a previous study, the critical values of the opening mode stress
intensity factor (K1), its equivalent, the strain energy-release rate (G1),
and the J integral (J1) (in the elastic case being equal to that of G1)
were determined for resin composite. In this study, the strength of the
composite-tooth interface was investigated. The critical values of K1 and
J1 were measured with single-edge notched-bend (SENB) specimens of resin
composite bonded to enamel, with the notch at midspan at the bonded
interface. Due to enamel's anisotropy, the values of Klc and Jlc to be used
in a fracture-mechanics application for failure prediction of a structure
depend on the enamel prism orientation relative to the adhesive interface.
Where interfacial failure is to be expected, the following values for Jlc
and Klc can be used: Silux, Jlc = 145 +/- 35 Jm-2 and Klc = 0.84 +/- 0.16
MNm-3/2; P-30, Jlc = 163 +/- 13 Jm-2 and Klc = 1.02 +/- 0.07 MNm-3/2. Where
enamel failure is expected or where the failure mode cannot be predicted,
the following values can be applied: Silux, Jlc = 89 +/- 15 Jm-2 and Klc =
0.84 +/- 0.16 MNm-3/2; P-30, Jlc = 89 +/- 15 Jm-2 and Klc = 0.75 +/- 0.10
MNm-3/2.
