Adhesion and microleakage tests of a new dentin bonding system

Adhesion to dentin and microleakage of a new dentin bonding system was studied. The new system includes a low viscosity lightly filled Bis-GMA based resin liner which is placed between the phosphate ester-containing adhesive layer and the composite. This system was compared to dentin bonding agents based on: 1) HEMA and Bis-GMA and 2) PMDM and NTG-GMA. The phosphate ester system was used with and without the low viscosity resin. Each system was used with its corresponding posterior composite. All groups were tested by shear and tensile bond testing immediately and up to 6 mon after bonding. Microleakage of the three systems was tested in Class V restorations by dye penetration. The results of the shear and tensile tests indicated that significant changes within groups occurred with time, and significant differences appeared between groups at various times. The use of low viscosity resin with the phosphate ester system resulted in decreased leakage. The amount of leakage observed was related to early shear bond strength. This study suggests that the properties of the layer immediately adjacent to the adhesive may affect the performance of the system.