THE EFFECT OF AIR THINNING ON DENTIN ADHESIVE BOND STRENGTH

The purpose of this study was to determine if air thinning three denti n adhesives would affect bond strength to dentin. Ninety human molars were mounted in acrylic and the occlusal surfaces ground to expose a f lat dentin surface. Thirty teeth were randomly assigned to one of the following dentin bonding agent/composite combinations: A) Universal Bo nd 3/TPH (Caulk), B) All-Bond 2/Bis-Fil-P (Bisco), and C) Scotchbond M ulti-Purpose/Z-100 (3M). The primers were applied following the manufa cturers' instructions. The adhesives were applied by two methods. A th in layer of adhesive was applied with a brush to 15 specimens in each group and light cured. Adhesive was brushed on to the remaining 15 tee th in the group, air thinned for 3 seconds, and then polymerized. The appropriate composite was applied in 2 mm increments and light cured u tilizing a 5 mm-in-diameter split Teflon mold. Following 3 months of w ater storage, all groups were shear tested to failure on an Instron Un iversal Testing Machine. Bond strength was significantly higher in all groups when the dentin bonding agent was painted on without being air thinned. Scotchbond Multi-Purpose had significantly higher bond stren gth than All-Bond 2, which had significantly higher bond strength than Universal Bond 3.