The bond strength of particulate-filler composite to differently oriented fiber-reinforced composite substrate.

PURPOSE

The primary failure mode of fiber-reinforced composite (FRC) materials used intraorally is delamination or debonding of particulate filler composite (PFC), the esthetic veneer, from the underlying FRC framework. The objective of the current study was to evaluate the effect of unidirectional fiber orientation and load direction on the shear bond strength of PFC to FRC.

MATERIALS AND METHODS

Unidirectional E-glass FRC was used as an adhesion substrate for the PFC. E-glass FRCs were oriented in three ways--Group A: in the plane perpendicular to the bonding surface; Group B: along the bonding surface longitudinal to the load; and Group C: along the bonding surface, transverse to the load. The FRC substrates were ground flat with 1200 grit. The PFC adherend was bonded to FRC using an intermediate resin. Twelve specimens for each group were water stored (37 degrees C) for 3 days before a shear bond strength test was conducted.

RESULTS

A one-way analysis of variance showed that the direction of the applied load to the fiber direction had a significant effect on the bond strength values (p < 0.001). A Weibull analysis produced values (characteristic strength and Weibull modulus) of Group A (46.5 MPa, 12.1), Group B (40.6 MPa, 4.6), and Group C (27.6 MPa, 3.5).

SIGNIFICANCE

The highest shear bond strength values and Weibull modulus were obtained when the fibers were oriented perpendicular to the bonding surface, exposing the fiber ends to the PFC. Interface strategies between hybrid composite layers may be developed to exploit anisotropic behavior in the adherence between FRC and PFC.