Bonding performances and histochemical evaluation of a novel glass-ionomer cement

Purpose: To evaluate the micro-shear bond strength (µSBS) and dentin endogenous enzymatic activity (MMPs) of a newly introduced glass-ionomer cement (GIC) based on an elastomeric micelle technology. Methods and Materials: Enamel-free, middle/deep dentin of human molars was exposed and dentin blocks were embedded in acrylic resin blocks. After dentin pre-treatment with their proper conditioner, 3 GICs with different compositions were used according manufacturer’s recommendations: 1) Fuji IX Capsule (GC Corp.); 2) Equia Forte HT (GC Corp.); 3) DeltaFil (DMG GmbH). The GICs were applied on the dentin surfaces by means of a disposable mold that was maintained until the complete setting of the materials. After 24 h of storage at 37 °C and 100% relative humidity, the µSBS test was performed. Additionally, freshly extracted sound molars were prepared (n=3 per group) with the same adhesive protocols as for µSBS, cut into slices, ground down and subjected to in situ zymography with a fluorescein-quenched gelatin. The data were statistically analyzed (p<0.05). Results: The type of GIC significantly influenced the bond strength (P<0.05). Shear bond strength of DeltaFil was significantly higher compared to that of Fuji IX (P<0.05). The latter presented higher bond strength values compared to Equia Forte, which had the lower values (p<0.05). The in situ zymography analysis revealed differences among the materials tested (P<0.05). Deltafil showed the lower MMP activity while Fujy IX revealed the higher level of fluorescence within the hybrid layer (P<0.05). Conclusions: For the first time, the dentin endogenous activity within the hybrid layer was recorded between GICs. The newly-marketed GIC based on an elastomeric micelle technology recorded the higher bonding values and lower enzymatic activity among groups. Long-term studies are warranted to better define the bonding behaviors of the tested materials.