| Objective:To observe the expression change and distribution of vascular endothelial growth factor(VEGF)and actin in rat dental pulp after direct pulp capping with mineral trioxide aggregate, to further clarify the mechanism of action involved in the damage pulp repair process, to provide the theoretical basis and experimental evidence for the preservation of pulp in the clinical.Methods:Thirty-five male Wistar rats were included in this study provided by the Hebei Medical University Experimental Center, weighing250-280g,2-3months, have good oral hygiene, no dental caries and periodontal disease.Thirty-five male Wistar rats were randomly divided into seven groups:1d,3d,5d,7d,14d,28d and the normal group, randomly selected one side of the maxillary first molar as the experimental side. The rats were anesthetized with10%chloral hydrate(3ml/kg)and sit-fixed, and2%tincture of iodine disinfection of the oral cavity,75%alcohol swab to disinfection the experimental side. Drilling and grinding in the occlusal fossa down to the bottom of the cave until revealed a pink, probe lightly pithing used homemade diameter0.5mm sharp probe in the bottom of the cavity. Normal saline flushed, sterile cotton ball soft reduction to stop bleeding, a small amount of MTA immediately set to the exposed pulp hole, filling with glass ionomer cement; normal group received no treatment and served as controls.The rats were anesthesia in1d,3d,5d,7d,14d and28d after direct pulp capping, to perfusion fixed within the heart40-60mins use4%paraformaldehyde solution, and then separated of the experimental side of the maxillary molar area rapidly, and cut the apical dense bone exposed tip, fixed48h and post in10%EDTA decalcification4w, running water overnight, and then removed the glass ionomer fillings. Embedded in paraffin and the preparation of slice, the slice thickness5μ m. Randomly selected the slice which pass through the pulp hole to staining, six in the group. One for HE staining, and the other for immunohistochemical(SP method)to VEGF and actin. To analysis the positive cell percentage and the staining intensity of VEGF and actin use Image Pro-Plus software and then overall rating, each group of points is multiplied by two ratings.To use SPSS13.0statistical software for data analysis. Kruskal-Wallis test was used to compare; between any tow groups were compared using Wilcoxon test. As a=0.05, if P value is≤0.05, there is difference statistically.Results:1The experiment change of VEGFThe normal group showed strong expression of VEGF in vascular endothelial cells, and weakly positive or no coloring expression in fibroblasts and odontoblasts. With the extension of time, the trend of the expression of VEGF was increased firstly and then reduced and last near normal levels. The expression parts were mainly located in the cells which were vascular endothelial cells, fibroblasts, odontoblasts. Among the3d expression began to increase,5d strongest,7d and14d had a slight decrease and then to28d, closed to the normal level.In the staining intensity test, the results of Kruskal-Wallis test showed that there was difference among the seven groups (H=24.425, P<0.05). The results of Wilcoxon test showed that there was no difference in the staining intensity between the normal group, Id,14d and28d (P>0.05). The staining intensity in the normal group was different from that in3d,5d,7d (P<0.05). The staining intensity in Id group was different from that in3d,5d,7d (P<0.05). The staining intensity in3d was different from that in7d,14d,28d (P<0.05). The staining intensity in5d was different from that in7d,14d,28d (P<0.05). The staining intensity between3d and5d was not statistically significant (P>0.05). The staining intensity in7d was no different from that in14d and28d(P>0.05). 2The experiment change of actinThe normal group showed strong expression of actin in the odontoblasts, and showed positive expression in vascular endothelial cells. With the time of pulp capping, the expression intensity of actin was first decreased and then enhanced and in the final trend of near-normal levels. The expression parts were mainly located in vascular endothelial cells and odontoblasts. In group3d, there ware some odontoblasts had arranged disorder, so the expression of actin was negative, and as the odontoblasts increased, the expression of actin gradually strengthened in group5d and7d, and to28d actin expression of basic back to normal levels.In the staining intensity test, the results of Kruskal-Wallis test showed that there was difference among the seven groups (H=19.637, P<0.05). The results of Wilcoxon test showed that there was no difference between the normal group, Id,14d and28d (P>0.05). The staining intensity in the normal group was different from that in3d,5d,7d (P>0.05). The staining intensity in the normal group was different from that in3d (P<0.05). The staining intensity in1d group was different from that in3d and7d (P<0.05). The staining intensity in the Id group was no different from that in5d (P>0.05). The staining intensity in3d was different from that in5d,7d,14d,28d (P<0.05). The staining intensity in5d was no different from that in14d and28d(P>0.05). The staining intensity in5d was different from that in7d (P<0.05). The staining intensity in7d was different from that in14d (P>0.05). The staining intensity in7d was different from that in28d (P<0.05).Conclusions:1The change trend of VEGF was first decreased and then increased and at last to close to the normal after direct pulp capping with MTA, this may be related to the defensive reactions and repair itself in the pulp after injury.2The change trend of actin was first increased and then diminished and then gradually increase, and had regional distribution characteristics, this may be related to the repair itself in the injury pulp.and the arrangement of odontoblast. |
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