REGIONAL STRENGTHS OF BONDING AGENTS TO CERVICAL SCLEROTIC ROOT DENTIN

The regional bond strengths of three current-generation bonding system s (All Bond 2, Scotchbond Multi-Purpose, and Clearfil Liner Bond 2) we re measured in natural wedge-shaped defects in the cervical area of ex tracted human teeth. A microtensile testing method was used to compare the strengths of resin bonds made to occlusal margins with those made to gingival margins. Controls consisted of normal teeth which had art ificial wedge-shaped defects, of the same depth and dimension, created with a high-speed bur. The results indicated that there were no regio nal differences in bond strength, although bonds made to natural lesio ns were from 20 to 45% lower than those made to normal dentin in artif icially created wedge-shaped defects, depending on the bonding agent. Scanning electron microscopy revealed that Clearfil Liner Bond 2 creat ed the thinnest hybrid layers, which were difficult to measure in the natural lesions. The natural lesions contained sclerotic dentin, where as the artificial lesions were composed of normal dentin. Although the bond strengths to sclerotic dentin were lower than those to normal de ntin, the absolute values (ca. 16 to 17 MPa) were high relative to pre vious-generation bonding agents.