Comparison of Four Fluoride Etchants in Bonding between curing Luting Agent

etchants were aqueous solutions of 5wt% sodium fluoride (NaF), ammonium tluoride (NH4F), sodium hydrogen fluoride (NaFHF), and ammonium hydrogcn fluoride (NH{FHF). Cast specimcns of commercially pure titanium were air-abraded with alumina, etched for 30 seconcls, and then primed with a phosphate primer. An acrylic rod was bollded to the spccimen with a tri-n-butylborane-initiated self-curing luting agent, Shear bond strengths were determincd before and after 10,OOO thermoeyclcs. Regarding pre-Lhermocycling bond strength, there were no significant diffcrcnees among' the etehants. After thermoeyc]ing, there was a deerease in bond strength for all groups. Nonetheless, the bond strengths of NaFHF and NH4FHF were significantly higher than those of NaF, NII4F, and non-etehed conLrol. In terms of bonding durability between resin and titanium, it was significantly improved when the titanium surface was microscopically roughened with alumina blasting and etching using NaFHF or NH4FHF.