effect of topical fluoride on surface of cast titanium and nickel-chromium: an in vitro study

objectives: the aim of this in-vitro study was to evaluate the effect of topical fluoride on surface of cast titanium and nickel-chromium. materials and methods: thirty-nine rectangular specimens of titanium (grade 2) and 39 rectangular specimens of nickel-chromium were cast in equal dimensions and divided into three groups of 13 samples each. group one specimens of titanium and nickel-chromium were placed in 2% neutral sodium fluoride (naf) solution for 16 minutes. group two specimens of titanium and nickel-chromium were immersed in 1.23% acidulated phosphate fluoride (apf) gel for eight minutes. group three specimens of titanium and nickel-chromium were immersed in distilled water for 16 minutes. the surface roughness of the specimens was evaluated and the data were analyzed using two-way anova and post-hoc comparison test with the level of significance set at 5% (p< 0.05). the surface of the specimens was further analyzed using a scanning electron microscope (sem) and energy dispersive spectrometer (eds). results : group two titanium specimens showed a statistically significant increase in surface roughness (p<0.05); but no statistically significant increase was noted in the surface roughness of nickel-chromium specimens in groups one, two and three (p>0.05). qualitative sem and eds analyses further revealed the surface corrosion of titanium (group two) and localized mild corrosive pitting of nickel-chromium specimens (group two). conclusion: topical fluoride with acidic ph affects the surface roughness of titanium and to a certain extent, nickel-chromium. neutral naf solutions cause no significant change in corrosion resistance of titanium or nickel-chromium.