In vitro corrosion of titanium

Titanium is used in dentistry for implants and frame work because of its sufficient chemical, physical and biological properties. The corrosion behaviour is from high interest to value biocompatibility. A static immersion test was undertaken with a titanium test specimen (30 mm x 10 mm x 1 mm, immersion time = 4 x 1 w, n = 3 for each series). The following parameters were investigated: specimen preparation, grinding, pH-value, different casting systems, comparison with CAD/CAM, influence of: chloride, thiocyanate, fluoride, lactate, citrate, oxalate, acetate. Atomic absorption spectroscopy was used to analyse the solutions weekly. The course of corrosion was investigated photometrically. Titanium reveals ion releases [(0.01-0.1) microg/(cm2 x d)] in the magnitude of gold alloys. There is little influence of grinding and casting systems in comparison with organic acids or pH value. The ion release increases extreme (up to 500 microg/(cm2 x d)) in the presence of fluoride. Low pH values accelerate this effect even more. Clinically, no corrosion effects were observed. Nevertheless it is recommended that it is best to avoid the presence of fluoride or to reduce contact time. In prophylactic fluoridation of teeth, a varnish should be used.