AIM:To investigate the effects of lipopolysaccharide(LPS) on matrix metalloproteinase-1(MMP-1) and tissue inhibitor of matrix metalloproteinase-1(TIMP-1) induction in human periodontal ligament cells(HPDLCs).METHODS:HPDLCs were stimulated with different concentrations of LPS(0.1,1,10,50,100 μg/mL).After 24 and 48 hours culture,MMP-1 and TIMP-1 levels in the culture media were measured by enzyme linked immunosorbent assay(ELISA) and the ratio of MMP-1 to TIMP-1 was calculated.RESULTS:LPS enhanced the expression of MMP-1 in a time-and concentration-dependent manner.TIMP-1 was decreased dose-dependently at 24 h post-stimulation,while a significant inhibition of TIMP-1 was observed only with 100 μg/mL LPS treatment at 48h post-stimulation.The ratio of MMP-1 and TIMP-1 was increased significantly.CONCLUSION:LPS can up-regulate MMP-1 expression and down-regulate TIMP-1 expression,therefore may play a role in periapical tissue destruction by breaking the balance of MMP-1 /TIMP-1.

Objective To detect the changes of intestinal microflora in children with Henoch-Schonlein purpura (HSP) accompanied by Helicobacter pylori (H.pylori) infection. Methods The fecal samples were collected randomly from 40 children with HSP and 40 healthy children. First, H.pylori stool antigens (HpSA) were tested for confirming H.pylori infection by Rapid Immuno Card STAT. Then, the bacterial DNA was extracted from the feces for detecting the bifidobacterium and Escherichia coli by 16SrRNA fluorescent quantitative PCR. Results The H.pylori-positive rates in children with HSP and healthy children were 50.0% and 27.5% respectively. The H.pylori-positive rates between children with HSP and healthy children had a significant differences (χ2 = 4.266, P < 0.05). Compared respectively with healthy children with or without H.pylori infection, children with HSP + H.pylori or children with H.pylori infection had a significantly lower logarithm amount of fecal bifidobacterium (P < 0.008 3). Compared with children with HSP and without H.pylori infection, the healthy children with or without H.pylori infection had a significantly higher logarithm amount of fecal Escherichia coli (P < 0.008 3); and children with HSP and H.pylori infection had a significantly higher logarithm amount of fecal Escherichia coli than children with HSP and without H.pylori infection (P < 0.008 3). Compared with children with HSP and without H.pylori infections, healthy children with or without H. pylori infection, the B / E value was significantly decreased (P < 0.008 3) in children with HSP and H.pylori infection. Conclusions The H.pylori-positive rate is significantly higher in children with HSP than in healthy children. HSP might be related to H.pylori infection. The intestinal bifidobacterium is significantly decreased in children with HSP than in healthy children. The intestinal Escherichia coli in children with HSP and H.pylori infection are significantly increased than in children with HSP and without H.pylori infection. The B / E value is significantly decreased in the children with HSP and H.pylori infection. It is suggested that the children with HSP and H.pylori infection have an obviously disorder of intestinal microflora.

PURPOSE:To evaluate the effect of smear layer on apical microleakage in extracted root-filled teeth by SEM and glucose penetration model.METHODS:51 straight single-rooted human teeth were randomly divided into 5 groups, instrumented and irrigated differently by groups. 11 teeth in group A were irrigated with 17% EDTA and 1% NaClO,11 teeth in group B with 1% tetracycline hydrochloride and 1% NaClO,11 teeth in group C with 10% citric acid and 1% NaClO, 9 teeth in group D with 1% NaClO only and 9 teeth in group E with 0.9% NaCl. One tooth in each group was observed under scanning electron microscopy. The other teeth were obturated using lateral condensation technique. Leakage along the root filling was measured by the concentration of glucose in apical reservoir at 1, 2, 4, 7, 10, 15, 20 and 30 days respectively with glucose oxidase method. The data were analyzed with repeated measure ANOVA and SNK-q test using SPSS 16.0 software package.RESULTS:No smear layer on the root canal wall was observed in group A, B and C, the leakage was lower than that in group D and E (P<0.05). The smear layer occurred in quantity in group D, E and their leakage increased. The microleakage was higher in group E than that in group D (P<0.05).CONCLUSION:Removal of smear layer on the root canal wall could reduce the root apical microleakage.