Effect of filler addition on the bonding parameters of dentin bonding adhesives bonded to human dentin

To determine the effect of filler addition on two total-etch, single component bonding systems on the bond strength, displacement at debonding, stiffness of debonding and energy absorbed to debonding of resin composites to human dentin.

Two dentin bonding systems with no-filler (OS and SB) and filler-added (OSP and SBP) versions were studied. The dentin surfaces of human teeth were exposed with 600-grit SiC. TPH Spectrum A2 was used to bond to the dentin surfaces in the form of a truncated cone, 3 mm in diameter at the bonding surfaces and 5 mm in diameter at the base. Bonded specimens were stored in distilled water at 37 degrees C for 24 hours. They were then debonded in tension with a universal testing machine at a cross-head speed of 0.5 mm/minute. Displacement at debonding, stiffness and energy to debonding were calculated based on the stress-displacement curve.

Bond strength, displacement at debonding and energy to debonding (measured and elastic) were influenced by the brand of the adhesive (OS/OSP vs. SB/SBP), but were not influenced by the filler addition based on two-way analysis of variance. Bond strength was in the range of 24.4-30.1 MPa, and there were significant differences between the bond strengths of OS and SB. Displacement and energy to debonding (measured and elastic) were different between the adhesives. Bond strength, bond stiffness and energy to debonding (measured) showed significant correlations.