THE EFFECT OF CONDITIONING ON ADHESION TO HUMAN DENTIN

The effect of conditioning dentin was investigated using ethyleneglycol bis(aminoethylether) tetraacetic acid (EGTA) and three proprietary agents containing ethylenediamine tetraacetic acid (EDTA), maleic acid and dipentaerythritol pentaacrylate phosphoric acid ester (PENTA). Ground dentin was treated with EGTA or one of the three proprietary agents. After adhering composite resin to treated surfaces, the shear bond strength (SBS) was determined with and without thermal stress. Scanning electron and atomic force microscopies were used to assess morphological effects of each of the agents, while low resolution X-ray photoelectron spectroscopy (XPS) was employed to evaluate elemental changes due to treatment. Mean bond strength was greatest for the PENTA-conditioned surfaces. EDTA and maleic acid demineralized the dentin surface while the agent containing PENTA produced an adherent surface film. The XPS survey showed a reduction in Ca and an increase in N for agents containing EGTA, EDTA and maleic acid, while a simultaneous reduction in both these species was observed for PENTA. EGTA did not improve adhesion for systems which were based on smear layer removal and substrate demineralization. For the PENTA-based system, which relied on the development of a molecular overlayer, EGTA degraded bond strength.