Electrochemical evaluation of the hydrogen peroxide- and fluoride-induced corrosive property and its recovery on the titanium surface.

PURPOSE: This study aimed to elucidate the effects of hydrogen peroxide (H2O2) and sodium fluoride (NaF) on titanium surfaces under conditions mimicking those encountered during dental treatment.

METHODS

Titanium samples were immersed in artificial saliva (AS), 1M H2O2, 1M H2O2 with catalase, 1000ppmF NaF, 1M H2O2 with 1000ppmF NaF, or 9000ppmF NaF (9000ppmF NaF: pH 5.3, other solutions: pH 6.5) for 3min. The electrochemical properties of the titanium samples were analyzed before and after the immersion procedures using a potentiostat. The amounts of titanium eluted into each solution were measured using inductively coupled plasma mass spectrometry. The post-immersion color changes (ΔE*ab) and gloss values of the titanium samples were determined using spectrophotometry. Moreover, the solution-treated titanium samples were subsequently immersed in AS and analyzed electrochemically at 1, 2, 3, 4, 6, 8, and 24h.

RESULTS

The immersion of titanium in any of the solutions except 1000ppmF NaF caused significant increases in corrosive and passive currents and significant reductions in polarization resistance. No titanium elution or color changes were observed, except when 9000ppmF NaF was used. After immersion in AS, the electrochemical properties of all of the titanium samples, except the 9000ppmF NaF-treated samples, recovered within 24h.

CONCLUSIONS

One M H2O2 and 1000ppmF NaF can be used alone or in combination in the clinical setting without causing significant titanium corrosion because the corrosive properties they induce is reversible. However, highly concentrated acidic fluorides can cause irreversible corrosion.