The effects of rinse volumes and air and water pressures on enamel-composite resin bond strength.

To assess the effect of different rinse volumes and air and water pressures on shear enamel-composite resin bond strength, the buccal surfaces of 384 maxillary molars were prepared through 600-grit silicon carbide, gel-etched, and rinsed with one of 24 randomly assigned test conditions: 0, 2, 5, 10, 15, or 25 ml volume wash with air and water syringe pressures of 20/10, 20/40, 40/10, or 40/40 psi. The rinsed enamel was dried, Scotchbond adhesive was applied, and a polysiloxane ring was secured to the flattened surface. Silux resin was incrementally added to a depth of 2 mm and each increment cured 40 seconds. Shear bond strengths were determined by using an Instron testing machine at a crosshead speed of 0.5 mm/min. A statistically significant (p less than 0.05) volume effect was found only between the 0 volume rinse groups and each other volume group. No statistically significant differences (p less than 0.05) were seen between air or water pressure groups. Mean bond strengths for greater than or equal to 2 ml rinsing ranged from 250 +/- 30 to 280 +/- 50 kg/cm2. Enamel-composite resin bond strengths were not significantly increased beyond 2 ml rinsing regardless of air and water syringe pressure used.