Objective To evaluate the effects of sonicated extracts of Porphyromonas gingivalis（P.gingivalis） on the viabilities of human periodontal ligament cells（hPDLC）. Methods In the experimental group, hPDLC obtained by the tissue culture were treated by sonicated extracts in different concentrations（6.25, 12.5, 25, 50 mg·L－1） for 24 hours. In the negative control group, hPDLC were treated without sonicated extracts. Furthermore, hPDLC were exposed to 12.5 mg·L－1 sonicated extracts for 24, 48, 72 and 96 h, while hPDLC in the negative group were cul - tured for 24, 48, 72 and 96 h without sonicated extracts. Cell viabilities in two groups were determined by methyl thiazolyl tetrazolium method and use SPSS 13.0 package for one-way analysis of variance and independent sample t-test. Results Sonicated extracts for hPDLC as the concentration of 6.25-50 mg·L－1, exposed for 24 h, the hPDLC viabilities of experimental group were lower than those of the negative group. When hPDLC were exposed to 12.5 mg·L－1 sonicated extracts, in the 24-96 h, the hPDLC viabilities of experimental group were lower than those of the control group. Conclusion Porphyromonas gingivalis can lead to decreased viabilities of hPDLC in vitro, in a dose and time dependent.
