Abstract:

Objective　Purpose of the studywas to investigate the content ofNickel(Ni) and Chromium(Cr) ion in gingival tis- sue and blood, and to discuss the reason of gray line in gingival afterwearing non-noble Porcelain-Fused-to-Metal crown.Methods 　38 rabbits were selected as experimental animals which were divided into three groups: control group, group 1(3 months) and group 2( 6 months ). The content of Ni and Cr ion in gingival tissue and blood was detected by atomic absorption spectrometer. Results　The amount of Ni and Cr in group 2 was significantly higher than that in other groups (P<0.05). There was no differ- ence between group 1 and control group (P>0.05).Conclusion　The reason of gingival colouration might be the electrochemical corrosion. The metal ion was released in gingival tissue and blood.

Key words: non-noble porcelain-fused-to-metal crown, nickel, chromium, gray line, electrochemical corrosion