Bond strengths to superficial, intermediate and deep dentin in vivo with four dentin bonding systems

The shear bond strength of four dentin bonding systems which remove or modify the smear layer were measured in vivo in dog canine and molar teeth as a function of dentin depth. Dentin bond strengths were higher with cuspid teeth compared to molar teeth. Most bonding systems gave higher bonds to superficial dentin and progressively lower bond strengths deeper dentin. The highest bond strengths were obtained with Clearfil Liner Bond, followed by Superbond C&B, Scotchbond 2 and Tenure. The former two bonding systems achieved shear bond strengths to cuspids that were > 10 MPa regardless of dentin depth while the latter two systems produced bond strengths < 10 MPa. In molars, the same ranking of bonding systems was noted but the value that separated the high from the low bonds was 5 MPa.