[Expression of quorum-sensing related genes during Enterococcus faecalis biofilm formation].

OBJECTIVE: To investigate the relationship between the expression of the quorum-sensing related genes during Enterococcus faecalis(Ef) biofilm formation. METHODS: Ef biofilms model was established in vitro and film formation process was observed by confocal laser scanning microscope at 6, 12, 24 and 48 hours respectively.Quantification of biofilms was achieved by staining with crystal violet.Real-time fluorescence quantitative PCR method was used to detect the expression of fsrB, gelE and sprE genes in the process of Ef biofilm formation. RESULTS: A lot of live and dead bacteria unevenly distributed in Ef biofilm. The quantity of biofilms increased with time within 24 hours and was 0 h:0.00 ± 0.00, 6 h:1.09 ± 0.13, 12 h:2.10 ± 0.79, 24 h:3.30 ± 0.13, which was significantly different among the 4 time period(P < 0.05). The quantity of biofilm at 48 h(3.51 ± 0.01) increased slightly compared with 24 h(3.30 ± 0.13) , but did not show significant difference.Quantitative real-time PCR showed that the expression of quorum-sensing related fsrB increased with time within 24 hours and was 0 h:9.98 ± 0.46, 6 h:23.45 ± 1.13, 12 h:47.30 ± 2.49, 24 h: 331.30 ± 2.18, which was significantly different among the 4 time period(P < 0.05). The expression of gelE was 0 h: 6.54 ± 0.73, 6 h: 14.26 ± 1.24, 12 h: 37.47 ± 2.35, 24 h:264.80 ± 5.10(P < 0.05). The expression of sprE was 0 h: 7.72 ± 0.74, 6 h: 21.15 ± 0.96, 12 h:49.87 ± 3.18, 24 h:441.89 ± 7.74, which was significantly different among the 4 time period(P < 0.05). CONCLUSIONS: The fsrB, gelE and sprE genes are closely related to the biofilm formation in Ef.

[The activity of osteoclast in peri-implant tissues in Beagle dogs].

PURPOSE: To observe the quantity and activity of osteoclast in peri-implant tissues dynamically. METHODS: An animal model of dental implants was established in 6 male Beagle dogs of 1-2 years old. Bone remodeling was tested at 3-, 7-,15-,30-,60- and 90-day after placement of implants. The mandibular bones were taken out and the morphological changes were observed under X-ray examination.Bone tissue samples underwent HE staining. The data were analyzed with SPSS13.0 software package. RESULTS: The most prominent period of osteoclasts occurred at 7-day after placement of implants. After 7 days of implantation, the activity of osteoclast gradually decreased. CONCLUSIONS: The active stage for bone remodelling in peri-implant tissues during unloading period is about 7 days after implantation.

Escin inhibits lipopolysaccharide-induced inflammation in human periodontal ligament cells.

Periodontitis is a chronic inflammatory disease associated with gram-negative subgingival microflora infection. Accumulating experimental evidence suggests that escin exerts anti-inflammatory and anti-edematous effects. This study was designed to investigate the in vitro effects of escin on the inflammatory reaction of human periodontal ligament cells (hPDLs). hPDLs were stimulated with lipopolysaccharide (LPS). The cells were treated with various concentrations of escin. The viability of hPDLs was evaluated using the MTT method. The expression of Toll-like receptor 2 (TLR2) in hPDLs and the levels of IL-1ß, TNF-α and IL-6 in the supernatant were measured. Escin significantly attenuated LPS-induced cytotoxicity in a concentration-dependent manner in hPDLs. Treatment with escin partly blocked the expression of TLR2. Escin also lowered the increase of pro-inflammatory cytokines (IL-1ß, TNF-α and IL-6) induced by LPS. The present findings show that escin exerts a protective effect against LPS-induced inflammation in hPDLs. It was also shown that escin is a promising medicine for the treatment of periodontitis.

[Expression of receptor activator nuclear factor kappa B ligand and osteoprotegerin in peri-implant soft tissue and bone tissue].

OBJECTIVE: To study mRNA expression of receptor activator nuclear factor kappa B ligand (RANKL) and its decoy receptor, osteoprotegerin (OPG) in peri-implant tissue during unloading period. METHODS: An animal model of dental implant was established in 6 male Beagle dogs of 1-2 years old. Bone remodeling was tested at 3, 7, 15, 30, 60 and 90 days since the placement of implants. RANKL and OPG mRNA expression were quantified by real-time polymerase chain reaction (PCR). Then mandibular bones were taken out and the morphological changes were observed by X-ray, bone tissue was tested by immunohistochemistry stain. RESULTS: The most prominent period of bone remodeling occurred at 7th day after the placement of implants. The expression of RANKL and OPG increased in a time-dependent manner in both soft and hard tissue. After 7 days they gradually decreased. CONCLUSION: RANKL and OPG can express in soft tissue, and the changing tendency is consistent with the change of bone remodeling, it indicates that RANKL and OPG play an important role in the bone remodeling.

[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.

[Clinical study of immediate placement and early loading of dental implants].

OBJECTIVE: To evaluate the clinical results of immediate placement and early loading of dental implants. METHODS: Sixty-four dental implants were inserted into the edentulous section of 37 patients immediately after the teeth were extracted. 36 implants were inserted by one-stage operation procedure, of which 17 implants were loaded immediately in 3 edentulous jaws by temporary mandibular overdenture. Fixed crown restoration were completed on 14 implants in 1 - 2 months and on 22 implants in 3 - 4 months. The two-stage operation for another 28 implants were performed after 3 - 6 months and then were restored by routine methods. RESULTS: All implants were inserted successfully and stable. There was no peri-implantitis and X-ray films indicated that no remarkable bone resorption occurred. There were no significant differences in the peri-implant depths of gingival pocket between early loading implants and routine restoration. CONCLUSIONS: Dental immediate implant and early loading after implantation can shorten the treatment period of implant-supported prosthesis. The short-term clinical performance was not different from the routine method.