The durability of denture base resins with a new type of organic-inorganic hybrid coating was examined after long-term water im-mersion.After water immersion for 1 80 days at constant temperature of 37 ℃ the flexural strength and elastic modulus of the samples with the coating were qualified with the national standerds,the controls were not.

Objective:To investigate the wear resistance of four low-shrinkage commercial composite resins and two traditional composite resins in vitro and discuss the relative influencing factors, and to illustrate the inner relationship of the wear resistance of resins and material composition.Methods:Four low-shrinkage commercial composite resins including CLEARFIL MAJESTY Posterior(CMP), Filtek LS(LS), Admira(AD), Kalore(KA) and two traditional composite resins including Filtek Z350XT (Z350), Solitaire2(S2) were chosen.The bar-shaped specimens were fabricated and mounted in a UMT-2 wear testing machine and abraded with the two-body media (distilled water) with a Si3N4 ball as antagonist.The maximum wear depth was determined after 14 400 cycles.The friction coefficient was determined during the test.The worn surfaces were examined with SEM.Results:CMP showed the lowest maximum wear depth and KA presented the highest maximum wear depth.The maximum wear depth ranked as follows: CMP

Objective:To transfect the non-viral vector polyethylenimine (PEI)mediated miR-2861 mimic into the MC3T3-E1 cell line,and to explore the transfection efficiency of PEI/miR-2861 complex and its effects on the proliferation and osteogenesis differentiation in pre-osteoblasts. Methods:The proper amount of PEI was blended with miR-2861 mimic and negative control (NC)separately in a ratio of N∶P=10∶1,and they were divided into experiment group and NC group. The NC/PEI complex acted as the NC group was used to eliminate the interference of osteogenesis from the addition of double-stranded RNA mimic.MTT assay was used to determine the optimal concentration of PEI/miR-2861 mimic complex.The fluorescence imaging technique and bulge-loop RT-PCR were used to detect the transfection efficiency and mRNA expression of miRNA-2861 in the cells with different concentrations (10,30, 50,and 100 nmol · L-1 ), separately.The osteogenesis ability of MC3T3 cells was identified with RT-PCR and Alizarin red staining with the selected concentration of PEI/miR-2861 by transient transfection.Results:Compared with blank control group,the proliferation rates of MC3T3 cells in 100 nmol·L-1 PEI/miR-2861 group was decreased significantly at 72 h (P < 0. 05 ). With the increasing of transfected concentration the transfection efficiency of miRNA/PEI complex was increased gradually.The results of Alizarin red staining and quantitative analysis showed that calcium deposits were more and bigger in experiment group after induced for 21 d,while both in blank control group and NC group they were less.Conclusion:The miRNA-2861 mimic can be effectively transfected into the MC3T3-E1 cell line and expresses with a high level,which is mediated by PEI as the gene vector.miR-2861 mimic has a certain ability of promoting osteogenesis differentiation of MC3T3-E1 cells.

OBJECTIVE: To prepare customized porous silicone orbital implants using embedded 3D printing and assess the effect of surface modification on the properties of the implants. METHODS: The transparency, fluidity and rheological properties of the supporting media were tested to determine the optimal printing parameters of silicone. The morphological changes of silicone after modification were analyzed by scanning electron microscopy, and the hydrophilicity and hydrophobicity of silicone surface were evaluated by measuring the water contact angle. The compression modulus of porous silicone was measured using compression test. Porcine aortic endothelial cells (PAOECs) were co-cultured with porous silicone scaffolds for 1, 3 and 5 days to test the biocompatibility of silicone. The local inflammatory response to subcutaneous porous silicone implants was evaluated in rats. RESULTS: The optimal printing parameters of silicone orbital implants were determined as the following: supporting medium 4% (mass ratio), printing pressure 1.0 bar and printing speed 6 mm/s. Scanning electron microscopy showed that the silicone surface was successfully modified with polydopamine and collagen, which significantly improved hydrophilicity of the silicone surface (P < 0.05) without causing significant changes in the compression modulus (P > 0.05). The modified porous silicone scaffold had no obvious cytotoxicity and obviously promoted adhesion and proliferation of PAOECs (P < 0.05). In rats bearing the subcutaneous implants, no obvious inflammation was observed in the local tissue. CONCLUSION Poprous silicone orbital implants with uniform pores can be prepared using embedded 3D printing technology, and surface modification obviously improves hydrophilicity and biocompatibility of the silicone implants for potential clinical application.
Animals ; Rats ; Swine ; Silicon ; Orbital Implants ; Endothelial Cells ; Porosity ; Silicones ; Printing, Three-Dimensional