中文摘要：

目的：研究咖啡因对牙科铸造合金耐细菌腐蚀性能的影响。方法：将镍铬合金试件和纯钛试件分为人工唾液,1.5mmol/L和5.0mmol/L咖啡因人工唾液溶液三个组。选择变形链球菌和血链球菌为实验菌,培养并配制成浓度为5×10^6cfu/mL的菌液。镍铬合金和纯钛试件按分组浸泡48h后取出加入到配制好的实验菌液中,于厌氧箱培养72h后用酶标仪检测合金表面细菌浓度并用原子力显微镜观察合金表面粗糙度。结果：酶标仪检测结果显示咖啡因组合金表面两种细菌的粘附量均小于人工唾液组,且随着咖啡因浓度的增加,细菌粘附量进一步减小,差异有统计学意义（P〈0.01）。相同浓度咖啡因组,镍铬合金表面细菌粘附量显著小于纯钛（P〈0.01）。原子力显微镜结果显示咖啡因组合金表面粗糙度显著小于人工唾液组（P〈0.01）。相同浓度咖啡因组,镍铬合金表面粗糙度比纯钛小,差异有统计学意义（P〈0.01）。结论：咖啡因可提高镍铬合金和纯钛对变形链球菌和血链球菌的耐腐蚀能力,对镍铬合金耐腐蚀的性能提高较纯钛显著。

英文摘要：

Objective： To evaluate influence of caffeine on anti-corrosion behavior of dental alloys to bacteria. Methods：Ni-Cr and pure titanium specimens were divided into three groups, artificial saliva, artificial saliva with caffeine in concentrations of 1.5mmol/L and 5.0mmol/L. Streptococcus mutans and Streptococcus sanguis were cultured as experimental bacteria and prepared with the concentration of 5 ×10^6cfu/m L. After dipping specimens into solution for 48h, the specimens were cultured with bacteria in the anaerobic chamber for 72h, detected by microplate reader and the roughness of specimens were scanned by atomic force microscopy（AFM）. Results： The amount of the two kinds of bacteria attached on the working surface of Ni-Cr and pure titanium specimens significantly decreased in the presence of caffeine compared to the artificial saliva group（P〈0.01）. The amount of attached bacteria decreased as the concentration of caffeine increases（P〈0.01）.After dipping into the same concentration of caffeine solution, the amount of bacteria attached on Ni-Cr alloys were lower than pure titanium（P〈0.01）. The results of AFM suggest the roughness of both the alloys were significant lower in the presence of caffeine than artificial saliva group（P〈0.01）. The roughness of Ni-Cr alloys was significant lower than pure titanium in the presence of same concentration of caffeine（P〈0.01）. Conclusion： The study shows the inhibitory capability of caffeine to both Ni-Cr and pure titanium in the circumstance of S. mutans and S. sanguis. The anti-corrosion capability of Ni-Cr alloys significant increases in the presence of caffeine compared to pure titanium.