OBJECTIVETo study the changes in surface morphology of cobalt-chromium alloy, pure titanium and high-cobalt chromium molybdenum alloy immersed in artificial saliva with different concentrations of fluoride, and to analyze the corrosion resistance of these metals.

METHODSThe three kinds of metal were polished and then were immersed in artificial saliva with different concentrations of fluoride (0%, 0.05%, 0.2%). All specimens were immersed for 3 weeks at (37.0 +/- 1.0) degrees C. Metal surface roughness before and after immersion were measured and analyzed by scanning electron microscope (SEM).

RESULTSMetal surface roughness was increased with the concentration of fluoride. The surface roughness of the Co-Cr group and Ti group had a statistically significant difference between before and after immersion at the fluoride concentration of 0.05% (P<0.01), and the difference between Co-Cr group and vitallium2000 group, Ti group and vitallium2000 group were statistically significant difference (P<0.01). The differences of three groups before and after immersion were statistically significant at the fluoride concentration of 0.2% (P<0.01), and the difference among three groups was statistically significant (P<0.01).

CONCLUSIONPatients who frequently use fluoride products should not use pure titanium or cobalt-chromium alloy prosthesis. Patients with these three metal prostheses are not advised to use high concentration fluoride products.