Evaluation of the interface between one-bottle adhesive systems and dentin by Goldner's trichrome

To evaluate the hybrid layers in interfaces between dentin and six contemporary one-bottle adhesive systems using a nondestructive differential staining micro-technique.

The adhesive systems used in this study were divided to three groups based on hydrophilic/hydrophobic component ratios (i.e. ability to dissolve in water), from highest to lowest as follows: Group 1 (Dentastic UNO.DUO, PermaQuick PQ1) > Group 2 (One-Step, Primer&Bond NT) > Group 3 (Optibond Solo, Single Bond). The occlusal third of the crown was removed from 36 extracted, unerupted human 3rd molars. Smear layers were created by abrading the dentin with 600 grit SiC under water. The exposed dentin was treated with one of the adhesive systems per manufacturer's instructions. After 24 hours in water, 3-5 microm thin sections of the adhesive/dentin (adhesive/dentin ) interface were cut with a microtome and stained with Goldner's trichrome. Stained thin sections from each prepared tooth were imaged with light microscopy.

The thickness and color difference of adhesive/dentin interfaces among these one-bottle adhesive systems were clearly visualized. The width of the hybrid layers varied, ranged from 4.1-9.2 microm for six adhesive systems. The color differences in the stained sections are reflected to the extent and degree to which the adhesive envelops the exposed collagen. Among these six bonding systems, resin encapsulation of collagen varied from highest to lowest as follows: Group 1 (UNO, PQ1) > Group 2 (OS, PBNT) > Group 3 (OP, SB). The differences in collagen encapsulation are dependent on the adhesive composition, or the ability to tolerate water during the infiltration of the wet demineralized matrix.