Objective To explore the protective effect of allicin on nicotine-induced oxidative damage to human periodontal ligament cells（HPDLCs）. Methods 1）Establish nicotine-induced oxidative damage model on HPDLCs. Use water-soluble tetrazolium（WST） colorimetric method to find out the nicotine concentration（X） that could inhibit HPDLCs’growth for the following experiments. 2）HPDLCs of the fifth passage were divided into 5 groups: The control group, the nicotine group and the nicotine+allicin groups（the concentration of allicin was 15, 30, and 60 μg·mL-1 respectively）. Different kinds of culture media were added. Similarly, use WST colorimetric method to choose the allicin concentration（Y） that could significantly improve the survival rate of HPDLCs. 3）HPDLCs were divided into 3 groups: The control group, the nicotine group, the nicotine +allicin group and different media were added. The glutathion（GSH） concentrations in HPDLCs were determined in 1, 4, 8, 12 and 24 h respectively. Results 0.8 mg·mL-1 nicotine could inhibit the HPDLCs survival rate significantly（77% of the control, P0.05）. The GSH concentrations of nicotine +allicin group were higher than that of the nicotine group always（P0.05）. Conclusion 60 μg·mL-1 allicin can protect the HPDLCs against oxidative damage induced by nicotine.
