Matrilin-4对大鼠牙髓损伤后修复性牙本质形成的促进作用

目的：研究Matrilin-4对大鼠牙髓损伤后修复性牙本质形成的作用，探讨其作为新型盖髓剂的可能性。方法：28只雄性Wistar大鼠，在大鼠的双侧上颌第一磨牙牙合面备洞至露髓后，左侧用含Matrilin-4的胶原蛋白海绵盖髓（Matrilin-4组），右侧用含磷酸盐缓冲溶液（PBS）的胶原蛋白海绵盖髓（PBS组），双侧均用玻璃离子封洞。分别于3、7、14和28 d灌流固定处死大鼠并取上颌双侧第一磨牙标本，HE染色和免疫组织化学染色观察分析各组大鼠修复性牙本质形成及成牙本质细胞中牙本质涎蛋白（DSP）的表达情况。结果：HE染色，3 d时与PBS组比较，Matrilin-4组穿髓孔下方较少量炎症细胞聚集，并可见明显的血管扩张；7 d时2组穿髓孔下方炎症反应加重，但Matrilin-4组明显轻于PBS组，且可见前期牙本质形成；14 d时Matrilin-4组露髓区域可被较连续完整的修复性牙本质桥覆盖；28d时，与PBS组比较，Matrilin-4组穿髓孔下方可见厚而完整的修复性牙本质桥，牙本质桥下面有重组的成牙本质细胞层。免疫组织化学染色，2组大鼠成牙本质细胞中DSP阳性表达强度在术后3、7和14 d呈逐渐增强趋势，28 d时减弱；盖髓后各时间点Matrilin-4组大鼠成牙本质细胞中DSP阳性表达强度均强于PBS组，且14 d时阳性表达达高峰。与PBS组比较，3、7和14 d时Matrilin-4组大鼠成牙本质细胞中DSP阳性表达强度明显升高（P<0.01）。结论：Matrilin-4对牙髓损伤后修复性牙本质的形成具有促进作用。

Promotion effect of Matrilin-4 on reparative dentin formation after dental pulp injury in rats

Objective: To study the effect of Matrilin-4 on the reparative dentin formation in the rats after dental pulp injury, and to explore its possibility to be used as a new capping agent. Methods: A total of 28 male Wistar rats were selected. A cavity on the occlusal surface of maxillary first molars on both sides was prepared in each rat. Matrilin-4 was applied on the left exposed pulp(Matrilin-4 group), and PBS was applied on the right exposed pulp(PBS group);and the cavities in both sides were covered with glass ions. On days 3, 7, 14 and 28 after operation, the rats were sacrificed,and the maxillary first molars on both sides of the rats were selected. HE staining and immunohistochemistry staining were used to observe and analyze the reparative dentin formation and the expression of dentin sialoprotein(DSP) in the odontoblasts. Results: The HE staining results showed that there were less inflammatory cells under the exposed pulp in that Matrilin-4 group at 3 d after operation compared with PBS group, and obvious vasodilation was found. At 7 d after operation, the inflammatory reaction under the exposed pulps in two groups was aggravated, but the inflammatory reaction in Matrilin-4 group was significantly lighter than that in PBS group, and the prophase dentin formation was found. After injury of 14 d,the pulp-exposed areas were covered by more complete dentin bridge in Matrilin-4 group; at 28 d after operation, compared with PBS group, there was a thick, complete and reparative dentin bridge under the exposed pulps, composed of tubular dentin in Matrilin-4 group, and there were reorganized odontoblastic layers beneath the dentin bridge. The results of immunohistochemistry showed that the positive expression strengths of DSP in the odontoblasts of the rats in two groups were gradually increased at 3, 7 and 14 d after operation, and were decreased at 28 d. The positive expression strengths of DSP in the odontoblast of the rats in Matrilin-4 group were stronger than those in PBS group at each time point after operation, and the positive expression strength reached the peak at 14 d. Conclusion: Compared with PBS group, the positive expression strength of DSP in the odontoblasts of the rats in Matrilin-4 group had significant differences (P<0.01) at 3, 7 and 14 d.