[Comparative analysis of 6 kinds of bacteria in the subgingival plaque in different types of patients with periodontal diseases].

PURPOSE: To detect the existence of Aa,Pg,Tf,Cr,Ec and Pn in the subgingival plaque, and determine their relationships among different types of periodontal diseases. METHODS: Dental plaques from 120 subjects were sampled, including 40 volunteers with health periodontal status(Group A) , forty patients with dental plaque-induced gingival diseases(Group B) and 40 patients with moderate or severe chronic periodontitis (Group C) . These samples were detected based on bacterial composition using the terminal restriction fragment length polymorphism of 16S rRNA genes by multiple-polymerase chain reaction. The data was analysed with SPSS 13.0 software package for Chi-square test. RESULTS: The detection rate of Pn, Cr and Pg had significant differences between group A and B. The detection rate of Ec, Cr, Pg, Aa and Tf had significant differences between group C and B. The detection rate of Ec, Pn, Cr, Pg, Aa and Tf had significant differences between group A and C. CONCLUSIONS: The rate of Ec, Pn, Cr, Pg and Tf detected in moderate or patients with moderate or severe chronic periodontitis are significantly higher than that in healthy subjects, indicating that these bacteria have certain correlation with chronic periodontitis. The rate of Ec, Cr, Pg and Tf detected in severe chronic periodontitis are significantly higher than that in dental-induced gingivitis, suggesting their close relationship with the progress of periodontal disease.

[Role of extracellular signal-regulated kinase in osteoblast differentiation on roughened titanium surfaces].

PURPOSE: The purpose of this study was to evaluate the effect of sand-blasted and acid-etched titanium surface on MC3T3-E1 murine pre-osteoblast cell differentiation, and investigate the pathway of regulating osteogenic differentiation of MC3T3-E1 cells on sand-blasted and acid-etched titanium surface in order to elucidate the regulatory mechanisms of surface roughness on osteoblastic differentiation. METHODS: The characteristic of PT polished titanium (PT), sand-blasted and acid-etched (SLA) titanium surface were examined by scanning electron microscopy (SEM). Real-time PCR was applied to detect the expression of osteogenic genes including Runx2, OSX, OCN and OPN of the MC3T3-E1 cells cultured on the 2 groups of substrates.ERK1/2 activities in MC3T3-T1 cells were measured by Western blot on SLA surface. The data was analyzed using SAS9.0 software package. RESULTS: The result of SEM observation showed that the PT surface was turned titanium surfaces with the mean peak to valley roughness (Ra) of 0.2 µm and the corresponding Ra value of SLA was 3.2 µm. The expression levels of Runx2, OSX, OPN and OCN were significantly higher and the cell proliferation was significantly lower on SLA surfaces than on PT surfaces (P<0.05). The expression levels of Runx2, OSX, OPN and OCN were up-regulated by the effect of SLA surface with PD98095. Compared with PT surface, ERK1/2 phosphorylation was continuously inhibited by SLA. Moreover, PT surfaces treated with PD98095 and SLA surfaces without PD98095 both demonstrated reduced ERK1/2 phosphorylation of the cells and the inhibitive effect of SLA surfaces was milder than that of PD98095. CONCLUSIONS: Surface roughness is an important factor that determines osteoblast behaviors. Surface roughness of titanium substrates seems to enhance the osteoblastic differentiation of MC3T3-E1 cells and the enhancing effect of surface roughness on cell differentiation may be mediated by suppressing the activity of ERK1/2 pathway.

[Effect of simvastatin on the function of MG63 cell line].

PURPOSE: To investigate the effect of simvastatin on the function of MG63 cell line. METHODS: The function of proliferation, osteoprotegerin (OPG) and osteocalcin (OC) gene expression, and migration of MG63 cells were detected with MTT, fluorescent real-time PCR and micro chemotaxis, respectively. The data was analyzed using ANOVA followed by Tukey test with SPSS14.0 software package. RESULTS: 10-9mol/L and 10-8mol/L concentrations of simvastatin slightly promoted MG63 cell proliferation; 10-7mol/L and 10-6mol/L concentrations of simvastatin greatly enhanced the OPG and OC mRNA expression; All concentrations of simvastatin had an inhibitory effect on MG63 cell migration. CONCLUSION: Simvastatin could promote bone defect regeneration by enhancing the bone-related genes expression.

[Effect of simvastatin on residual ridge resorption after tooth extraction].

OBJECTIVE: To observe the effect of simvastatin carried by poly (lactide-co-glycolide) (PLGA) on residual ridge resorption following tooth extraction. METHODS: Sixty male Wistar rats were divided into experimental groups and control groups (30 rats/group). PLGA was immediately implanted with or without simvastatin into extraction sockets of the mandibular incisors. Soft X-ray photography, bone mineral density (BMD) and histopathologic study were conducted at 7, 14, 28, 56, and 84 days after implantation. RESULTS: The relative length values of residual alveolar ridge of the experimental groups were greater than those of the controls at 14, 28, 56, and 84 days after implantation, and there was a significant difference between the experimental and control groups (P < 0.05). The BMD of the specific region was higher in the experimental groups [(7.101 +/- 0.025), (7.178 +/- 0.039), and (7.162 +/- 0.052) g/cm(2)] than that in the control groups [(7.074 +/- 0.014), (7.117 +/- 0.012), and (7.059 +/- 0.037) g/cm(2)] (P < 0.05) after 28, 56, and 84 days. Light microscopy showed that bone formation rate and quality of the experimental group were better than those in the control group at the same time. CONCLUSIONS: Simvastatin carried by PLGA could induce bone formation of tooth socket. Local application of simvastatin would be potential to preserve the length and bone volume of alveolar ridge after tooth extraction.