Fracture-mechanics Parameters of the Composite-Enamel Bond

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 K1and J1were 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 K1cand J1cto 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 J 1cand K1ccan be used: Silux, J1c = 145 ± 35 Jm-2 and K1c = 0.84 ± 0.16 MNm-3/2; P-30, J1c = 163 ± 13 Jm-2 and K1c = 1.02 ± 0.07 MNm-3/2. Where enamel failure is expected or where the failure mode cannot be predicted, the fol...