ABSTRACT
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.