RESUMEN
Objective To evaluate the biological effect of tumor necrosis factor-α(TNF-α) on the proliferation and multi-directional differentiation of stem cells from rat apical papilla(SCAP).Methods SCAP was extracted by combining enzyme digestion method with tissue block method.The cells were divided into control group(TNF-α 0 ng/mL) and experimental group(TNF-α 5,10,20,50 ng/mL).The ability of proliferation of SCAP was measured by MTT method.The ability of osteogenic/dentinogenic differentiation of SCAP was measured by alizarin red staining and quantitative real-time PCR.The ability of adipogenic of SCAP was measured by oil red O staining.The expression of vascular related genes of SCAP was measured by quantitative real-time PCR.Results SCAP was consistent with the characteristics of mesenchymal stem cells and possessed the ability of multi-directional differentiation.The MTT results showed that experimental group promoted the proliferation of SCAP in comparison with the control group.The difference was statistically significant(P<0.05),and 10 ng/mL was the optimum concentration.The results of alizarin red staining showed that with the increase of the concentration of TNF-α,the mineralized nodules in the experimental group gradually became smaller,and the number of the formation decreased gradually.The results of quantitative real-time PCR showed that the expression of OC,DMP-1 and DSPP in the experimental group was significantly lower than that of the control group at 3 and 7 days,in which the expression of OC was statistically significant different(P<0.05);at 14 days,the expression of OC,DMP-1 in the experimental group was significantly lower than that of the control group(P<0.05).The result of Oil red O staining showed that with the increase of the concentration of TNF-α,the lipid droplets formation in the experimental group gradually decreased.The result of quantitative real-time PCR showed that the expression of ANGPT1,VEGFA,PECAM-1 in the experimental group was significantly lower than that of the control group(P<0.05).Conclusion TNF-α might promote the proliferation and inhibit the multi-directional differentiation of SCAP.
RESUMEN
BACKGROUND:Due to the complexity and irregularity of bypass obturation of oval root canal and the particular stress of the post and core to the tooth, we have not yet found a reasonable post crown for dental restoration after bypass obturation of the oval root canal. OBJECTIVE:To compare the flexural capacity of the three kinds of post-and-core repair systems (cobalt-chromium cast post and core, zirconium oxide post and core, and CAD/CAM-fabricated glass fiber post and core) after bypass obturation of the oval root canal warm gutta. METHODS: Ninety mandibular first premolars were selected for bypass obturation of the root canal with Obtura II & System B, and then randomized into three groups that were respectively restored with cobalt-chromium cast post and core, zirconium oxide post and core and CAD/CAM-fabricated glass fiber post and core. After that, cobalt-chromium metal crown was used for ful-crown restoration. Fracture strength and fracture type were recorded in different groups. RESULTS AND CONCLUSION: The fracture resistance was higher in the cobalt-chromium cast post and core group and zirconium oxide post and core group than the glass fiber post and core group (P < 0.05), and the former two groups had no significant difference. Cobalt-chromium cast post and core was fractured at the root of tooth, and could not be repaired; the zirconium oxide post and core was fractured at the root neck and root of tooth, which was confirmed as reparative fracture; the glass fiber post and core was fractured at the tooth neck, which could be restored. These findings indicate that the cobalt-chromium cast post and core can bear greater occlusal force, but has a higher probability of root fracture; the CAD/CAM-fabricated glass fiber post and core exhibits a lower probability of root fracture