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[Influence of TiN, TiCN coating on corrosion resistance of dental pure titanium].

PURPOSE
To investigate the effects of TiN and TiCN coating on corrosion resistance of pure titanium in the simulated oral environment.


METHODS
The dental pure titanium commonly used in making removable denture was casted with 15 specimens, 10mm × l0mm × 1mm in size. The specimens were randomly divided into group A, group B and group C. In the group B and group C, the specimens were coated with a thickness of 2.5μm TiN and TiCN coating on surface by multi-arc physical vapor deposition, respectively. After microscopic energy spectrum analysis, microstructure and phase diffraction were examined by FESEM. Hardness and Young modulus of the various coating were determined by nanoindentation. The polarization curves of all specimens in artificial saliva were measured by PARSTAT' 2273 electrochemical station. The data were analyzed with SPSS 17.0 software package for t test, one-way ANOVA and nonparametric test.


RESULTS
Both the microhardness and elastic modulus in the group B and group C were significantly superior to those in the group A (P<0.001). Meanwhile, both the microhardness and elastic modulus in the group C were significantly higher than those in the group B (P<0.01). Corrosion potential (Ecorr) was group A > group B > group C (P<0.05). However, corrosion current density (Icorr) was significantly lower in the group A than in the group B, and in the group A than in the group C (P<0.01), while not significantly different between the B and group C (P>0.05).Breakdown potential (Ebreak) was group A<group B<group C(P<0.05).


CONCLUSIONS
Both TiCN coating and TiN coating can improve corrosion resistance of pure titanium in artificial saliva. However, TiCN coating is superior to TiN coating in improving corrosion resistance of pure titanium.