Objective The purpose of the study was to investigate the content of nickel（Ni） ion in patients′ saliva after wearing the porcelain -fused -to nickel -chromium（Ni -Cr） crown or the porcelain -fused -to nickel -chromium - titanium（Ni-Cr-Ti） crown. Methods 50 patients who had one molar or premolar needed repairing were selected and divided into two groups randomly. Patients in one group were fabricated with porcelain-fused-to Ni-Cr crown and the patients in the other group were fabricated with porcelain-fused-to Ni-Cr-Ti crown. Collect the patients′ saliva before wearing, 1 week, 3 months, and 6 months after wearing. The content of Ni ion in saliva was detected by inductively coupled plasma mass spectrometry（ICP-MS）. Results The content of Ni ion in both groups increased at the first week, and go back after 6 months. There were no significant differences before wearing, 1 week, 3 months, and 6 months after wearing. There were no significant differences between the two groups. Conclusion Wearing the porcelain- fused-to Ni-Cr crown or the porcelain-fused-to Ni-Cr-Ti crown has no significant influence on the content of Ni ion in saliva.
