Microbiologically induced corrosive properties of the titanium surface.

Area of Science:

• Biomaterials Science
• Microbiology
• Electrochemistry

Background:

• Titanium is widely used in dental restorations.
• Corrosion of titanium is a significant concern for dental implant longevity.
• Understanding microbiologically influenced corrosion (MIC) is crucial for improving dental material performance.

Purpose of the Study:

• To investigate the mechanism by which Streptococcus mutans induces corrosion in titanium.
• To elucidate the role of bacterial metabolism and oxygen concentration in titanium corrosion.
• To assess electrochemical changes on the titanium surface in the presence of viable and killed bacteria.

Main Methods:

• Experimental setup using polymethyl methacrylate wells with pure titanium.
• Monitoring pH at the bacteria-titanium interface with and without glucose.
• Electrochemical measurements (potentiostat) before and after incubation.
• Monitoring oxygen concentration using fluorescent film.
• Measuring titanium elution via inductively coupled plasma-mass spectrometry.

Main Results:

• Corrosion and passive currents increased with viable cells, unlike killed cells.
• Polarization resistance and oxygen concentration decreased significantly under viable cells.
• No titanium elution was detected, indicating surface corrosion rather than dissolution.
• Viable bacteria, regardless of glucose, induced electrochemical changes.

Conclusions:

• Viable Streptococcus mutans can induce titanium corrosion.
• Metabolism-coupled oxygen consumption by viable bacteria forms 'oxygen concentration cells'.
• These oxygen concentration cells contribute to the corrosive properties of the titanium surface in dental environments.