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Objective@#To study the effect of stem cell factor (SCF) on the angiogenic ability of cocultured dental pulp stem cells (DPSCs) and human umbilical vein endothelial cells (HUVECs).@*Methods @#This study has been reviewed and approved by the Ethics Committee. The experiment was split into the HUVECs, SCF+HUVECs, DPSCs+HUVECs, and SCF+DPSCs+HUVECs groups. A mixture of SCF and culture medium was used to prepare a mixed culture medium with an SCF concentration of 100 ng/mL. In vitro coculture of DPSCs and HUVECs was performed at a 1∶5 ratio. CCK-8 proliferation assay was used to observe the proliferative capacity of cells in each group on days 1, 3, 5, and 7. Wound healing and Transwell migration assays were used to detect the effect of SCF on cell migration under either direct or indirect coculture conditions, respectively. In vitro angiogenesis experiments were performed to detect the angiogenic capacity of the cells in each group. The vascular endothelial growth factor A (VEGFA) concentration in the cell culture supernatant was detected using ELISAs, and the protein expression levels of CD31, CD34, and VEGFA were detected using Western blot analysis. @*Results @# Wound healing and Transwell migration experiments showed that SCF significantly promoted the migration of cocultured DPSCs and HUVECs (P<0.05). The in vitro angiogenesis experiment showed that the number of branches and the total length of branches of tubular structures in the SCF+DPSCs+HUVECs group were significantly greater than those of the other groups (P<0.05), and the expression levels of the vascular-related proteins CD31, CD34, and VEGFA in this group were greater (P<0.01). @*Conclusion @# SCF can enhance the migration and in vitro angiogenesis of cocultured DPSCs and HUVECs.
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Objective@# To observe the effect of dopamine pretreatment of the root canal on improving the bonding performance of AH-plus sealer.@*Methods @# A total of 32 freshly isolated permanent teeth with a single canal were collected, with no caries, no fracture of roots, and a root canal curvature<10°. All sample root canals were prepared to F2 with ProTaper rotating nickel-titanium instruments and then treated with 1 mg/mL, 2 mg/mL, or 3 mg/mL dopamine solution for 24 hours and divided into 4 groups (n = 8): 0 mg/mL dopamine group (blank control group), 1 mg/mL dopamine group, 2 mg/mL dopamine group, and 3 mg/mL dopamine group. Scanning electron microscopy was used to observe the combination of dopamine and root canal dentin wall; laser confocal scanning microscopy was used to observe the penetration of AH-plus sealer; and root canal filling was performed with AH-plus sealer and gutta-percha tip using the cold gutta-percha lateral pressure technique. The root canal samples were cut horizontally at the middle and the apical third sections of the root with a slice thickness of 1-2 mm. The push-out test was carried out under an Instron universal testing machine to compare the push-out bonding strength between each group. @*Results @#Scanning electron microscopy showed that most of the dentinal tubules were open in the control group after 0 mg/mL dopamine solution treatment for 24 hours. In the 1 mg/mL group, a small number of dopamine particles on the surface of the dentin tubules in the inner wall of the root canal were loose and unevenly distributed. In the 2 mg/mL group, most of the dentinal tubules were covered by dopamine particles, and the dopamine layer was uniform and dense. In the 3 mg/mL group, a large number of dopamine particles were deposited at the mouth of the dentinal tubules, but the distribution was uneven. Dopamine and AH-plus sealer can be seen to simultaneously infiltrate into dentinal tubules under a confocal laser scanning microscope. The interaction of the two factors, the anatomical location and dopamine concentration, had no significant effects on the bonding strength of AH-plus sealer (P>0.05). Root canals treated with 2 mg/mL dopamine had the highest bonding strength in all groups (P<0.05). Analysis of the push-out test of bonding strength with AH-plus sealer at different anatomical locations showed significant differences (P<0.05). The push-out bonding strength of the AH-plus sealer in the middle third section of the root was higher than that in the apical third section of the root.@*Conclusion@# Different dopamine concentrations could affect the bonding strength of AH-plus sealer in root canals. When treated with 2 mg/mL dopamine for 24 hours, the bonding effect of AH-plus sealer in root canals was improved.
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Objective@# To investigate the effects of graphene on the proliferation, migration and cell morphology of dental pulp stem cells (DPSCs).@*Methods@#Graphene powder was prepared by the oxidation-reduction method, and a 0.5 mg/mL graphene dispersion was prepared. Raman spectroscopy and atomic force microscopy were used to characterize the structure and surface morphology of graphene. DPSCs were isolated and cultured in vitro. MTT assay was used to detect the effects of different concentrations of graphene dispersions (0, 1, 5, 10, 20, 50, 100 μg/mL) on the proliferation and wound healing assay was used to detected the migration abilities of DPSCs. The effects of graphene on the morphology of DPSCs were observed by immunofluorescence staining. @*Results @# In the present study, compared with the control group (0 μg/mL), the proliferation of DPSCs in the 100 μg/mL group was inhibited at 72 h (P < 0.05), and the proliferation of DPSCs in the other groups was not significantly affected (P > 0.05). Graphene dispersions at 10 and 20 μg/mL promoted the migration of DPSCs (P < 0.05). After being cultured in 20 μg/mL graphene dispersions for 3 days, the DPSCs showed a large and orderly cytoskeletal structure, and the spread area of cells was not significantly different from that of the control group (0 μg/mL) (P > 0.05), while some cells had the morphological characteristics of nerve cells.@* Conclusion @# Graphene has good biocompatibility and is expected to be a suitable material for tissue engineering within fitting concentration.
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Objective @#To analyze the effect of different cavosurface angles on the stress distribution of ClassⅠ cavity composite resin filling of molars through the three-dimensional finite element method and to provide references for the preparation of ClassⅠ cavities.@*Methods@#Three-dimensional finite element models of ClassⅠ composite resin filling of mandibular first molars with three different cavosurface angles (group A: 90°, group B: 120°, group C: 135°) were established. Polymerization shrinkage of composites was simulated with a thermal expansion approach. The mechanical behavior of the restored models in terms of stress and displacement distributions under the combined effects of polymerization shrinkage and occlusal load (600 N) was analyzed.@*Results@# For ClassⅠ cavities with the same cavity size, the total stress of the restoration model and the maximum stress of the enamel in group A were less than those in groups B and C after cavity composite resin restoration with three cavity cavosurface angles (in which the width of the enamel bevel was 1 mm in groups B and C). The maximum stress of the dentin and adhesive was similar in the three groups, the maximum stress of the composite in group C was the largest, and the maximum stress of the composite in group B was the smallest. In terms of stress distribution, the maximum stress in each restoration model was mainly concentrated in the enamel at the cavosurface, near the enamel-dentin interface and at the edge of the restoration material.@*Conclusion@#From the point of reducing the stress of residual tooth tissue, the preparation of 90° angle without enamel bevel is an ideal method for cavity preparation when composite resin is used to fill ClassⅠ cavities of molars.
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Abstract We recently demonstrated that a co-culture system of human umbilical vein endothelial cells (HUVECs) and human dental pulp stem cells (hDPSCs) could enhance angiogenesis ability in vitro. However, whether tumor necrosis factor α (TNF-α) could promote blood vessel formation during pulp regeneration remained unknown. The aim of this study was to investigate the effects of TNF-α on the formation of endothelial tubules and vascular networks in a co-culture system of hDPSCs and HUVECs. hDPSCs were co-cultured with HUVECs at a ratio of 1:5. The Matrigel assay was performed to detect the total tubule branching lengths and numbers of branches, and the Cell-Counting Kit 8 assay was performed to examine the effect of TNF-α on cell proliferation. Real-time polymerase chain reactions and western blot were used to detect vascular endothelial growth factor (VEGF) mRNA and protein expression. The Matrigel assay showed significantly greater total branching lengths and numbers of branches formed in the experimental groups treated with different concentrations of TNF-α compared with the control group. The decomposition times of the tubule structures were also significantly prolonged (P < 0.05). Treatment with 50 ng/ml TNF-α did not significantly change the proliferation of co-cultured cells, but it significantly increased the VEGF mRNA and protein expression levels (p < 0.05). In addition, the migration abilities of HUVECs and hDPSCs increased after co-culture with TNF-α (p < 0.05). TNF-α enhanced angiogenic ability in vitro in the co-culture system of hDPSCs and HUVECs.