Morphological interface between hybrid ionomers and dentin with and without smear-layer removal

To evaluate the micromorphological interface between dentin and several hybrid ionomer restoratives, a flat dentin surface was obtained on the occlusal surfaces of extracted human molar teeth after sectioning the enamel with an Isomet saw. Three poly-acid-modified composite resins, Compoglass, Dyract and F2000, and two resin-modified glass-ionomer cements, Fuji II LC and Photac-Fil were applied to the dentin surface. A second section, 2 mm apical from the first one, was made to produce a dentin segment containing the tested materials. Each disc was then split fractured along the dentin/material interface. For the poly-acid-modified composites, one half of the disc was stored in 6 mol/L HCl for 48 h to remove the dentin. The other was gently decalcified and deprotenized at the interface between the hybrid ionomer and the dentin. Both halves were then sputtered with gold and examined using SEM. For resin-modified glass-ionomer, samples were only evaluated at the interface. The three poly-acid-modified composite resins showed the formation of hybrid layers and resin tags at the interface to the dentin. Removal of the smear layer significantly improves hybridization of these materials. Also, Fuji II LC produced a hybrid layer while the Photac-Fil showed no evidence of hybridization.