Corrosion behaviour of titanium in the presence of Streptococcus mutans

Objective: The main aim of this in vitro study was to evaluate the influence of Streptococcus mutans on the corrosion of titanium. Methods: S. mutans biofilms were formed on commercially pure titanium (CP-Ti) square samples (10 mm x 10 mm x 1 mm) using a culture medium enriched with sucrose. Open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) measurements were used to evaluate the corrosion behaviour of CP-Ti in the presence of S. mutans in Fusayama's artificial saliva. The corrosion of biofilm-free CP-Ti samples was also evaluated in artificial saliva. Biofilms biomass was measured by spectrophotometry, using crystal violet staining, after 1, 2 and 7 days. Results: The OCP values recorded on CP-Ti in the presence of S. mutans (-0.3 +/- 0.02 V vs. SCE) was lower than those on biofilm-free CP-Ti (-0.1 +/- 0.01 V vs. SCE) after 2 h of immersion in artificial saliva (p < 0.05). That reveals a high reactivity of titanium in presence of S. mutans. Impedance spectra revealed the formation of a compact passive film on titanium in artificial saliva or in the presence of a 2 days old S. mutans biofilm even though the corrosion resistance of CP-Ti has decreased in presence of a S. mutans biofilm. Conclusion: The presence of bacterial colonies, such as S. mutans, negatively affected the corrosion resistance of the titanium. (C) 2013 Elsevier Ltd. All rights reserved.