Morphology and thickness of the diffusion of resin through demineralized or unconditioned dentinal matrix.

The formation of a hybrid layer is the main bonding mechanism of current dentin-bonding systems. This study evaluated the morphology and thickness of the resin-infiltrated dentinal layer after the application of adhesive systems. The dentin-bonding agents were evaluated on flat dentinal preparations confected on the occlusal surfaces of human teeth. The test specimens were prepared and inspected under scanning electron microscopy at a magnification of X 2,000. The adhesive systems were responsible for different hybrid layer thicknesses (p < 0.05), and the mean values were: for Scotchbond MP Plus (SM), 7.41 +/- 1.24 micrometer for Single Bond (SB), 5.55 +/- 0.82 micrometer for Etch & Prime 3.0 (EP), 3.86 +/- 1.17 micrometer and for Clearfil SE Bond (CB), 1.22 +/- 0.45 micrometer. The results suggest that the conventional three-step adhesive system (SM) was responsible for the thickest hybrid layer, followed by the one-bottle adhesive (SB). The self-etching adhesives, EP and CB, produced the formation of the thinnest hybrid layers.