Dentin infiltration by three adhesive systems in clinical and laboratory conditions

To evaluate in vivo and in vitro the formation of hybrid layer, resin tags and adhesive lateral branches, by use of three different enamel dentin bonding systems.

The dentin adhesives were tested on flat dentin preparations made on buccal surfaces of vital, periodontally compromised teeth. The samples were randomly divided in four groups: Group 1: Prime & Bond 2.0; Group 2: Scotchbond Multi-Purpose Plus; Group 3: Clearfil Liner Bond 2 (the self-etching primer was applied for 30 seconds on the enamel and dentin); Group 4: Clearfil Liner Bond 2 (the self-etching primer was applied for 60 seconds on the enamel and dentin). The sample teeth were extracted immediately after the bonding was cured. The same procedure described for the in vivo samples was performed in vitro on extracted molars. All the samples were split-fractured along their long axis. Half of the samples were used to visualize the hybrid layer and the other half to observe the morphology of resin tags by use of scanning electron microscopy.

All the tested products formed a hybrid layer, both in vivo and in vitro. In many areas of the samples of Groups 1, 2 and 4, characteristic reverse cone-shaped tags with their corresponding adhesive lateral branches were evident. In contrast to this, resin tags found in samples of Group 3 were narrower at the tubule orifices, and adhesive lateral branches were scarce. The length of the resin tags observed in the samples of Groups 1 and 2 were longer than those found in Groups 3 and 4. The morphology of the hybrid layer of the in vivo samples was similar to that of the in vitro samples.