Bonding efficiency and interfacial morphology of one-bottle adhesives to contaminated dentin surfaces

To evaluate the effect of dentin contamination with water, saliva or blood on the bond strength of one-bottle dentin adhesives and interfacial morphology.

The tested materials were Scotchbond 1, One-Step, Prime & Bond 2.1 and Syntac SC. The three-step bonding system Scotchbond Multi-Purpose Plus (SMP) was also included as control. Extracted human molars were used. For each tooth, enamel was removed by sectioning with a diamond saw and a smear layer was created by grinding on wet 600 grit SiC paper. Before the adhesive materials were applied and cured, the dentin was dried with air for 3 s, dried with a damp cotton pellet, or contaminated with saliva or blood. Cylinders of the composite resin Z100 were applied onto the adhesive dentin surfaces using Teflon split molds. After 24-hour water storage, the shear bond strength of the specimens was determined using an Instron testing machine at a crosshead speed of 0.5 mm/min. The morphology of the dentin-resin interface was examined using SEM.

Wetting of the substrate significantly increased the bond strength produced by One-Step, while the bond strength of Syntac SC was significantly decreased. The bond strength produced by Scotchbond 1, Prime & Bond 2.1 and SMP showed a slight increase or decrease, which was not significant. Saliva contamination decreased the bond strength significantly of only Syntac SC, while blood contamination significantly decreased the bond strengths of all materials. SEM evaluation of the dentin-resin interface showed a relation between resin tag formation and bond strength.