Repair Effect Of Matrilin-4 In The Process Dental Pulp Injury In Rats

ObjectivesRats were used to establish a model of dental pulp injury repair.Matrilin-4 was used as a capping agent to the injuried pulp.Morphological changes and immunostaining results of rat pulp tissue at different time points were observed.To investigate the effect of matrilin-4 on the activity of odontoblasts and the formation of repaired dentin.Methods:28 male Wistar rats that had been adaptively reared were randomly divided into 4 groups(n=7).In each group of rats,the bilateral maxillary first molar occlusal surface was prepared near the pulp,and the pulp was pierced with a probe.Matrilin-4 was applied on the left exposed pulp,and PBS was applied on the right exposed pulp.On day 3,7,14 and 28 after operation,the rats were sacrificed.The tooth were stained with HE and immunohistochemistry.The reaction of dental pulp tissue,the formation of reparative dentin and the expression of DSP in odontoblasts were observed.Results:Observed HE staining found that:3 days after surgery,the matrilin-4 group accumulated a small amount of inflammatory cells under the exposed pulp compared with the PBS group,and obvious vasodilation was observed.After 7 days,the inflammatory reaction under the exposed site was aggravated compared with the--Matrilin-4 3d group,but it was significantly lighter than the PBS 7d group,and the vasodilation was obvious.Prophase dentin formation was induced on the pulpal dentin walls along the periphery of the exposed site.After injury of 14 days,there was a more complete dentin bridge.However,pulpal tissue and the incompletely absorbed maternal still remained in the reparative dentin,and tunnel defect was shown between the reparative dentins.There was a complete reparative dentin,composed of tubular dentin,on the dentin side.There were reorganized odontoblastic layers beneath the dentin bridge.After 28 days,there was a thick,complete dentin bridge,composed of tubular dentin.There were reorganized odontoblastic layers beneath the dentin bridge.Pulpal morphology is normal.The results of immunohistochemistry showed that positive expression of DSP in the two groups gradually increased at 3,7 and 14 days after operation,and decreased at 28 days.And the positive expression of DSP in odontoblast of Matrilin-4 group was stronger than that in the PBS group at each time point,and the positive expression reached the peak at 14d.Matrilin-4 group showed stronger DSP exoression(P<0.05)than PBS group at 3?7?14 d.Conclusions:As a pulp capping agent,marilin-4 is used in the pulp exposed area of mechanical damage in rats,which can enhance the activity of odontoblasts and promote the formation of reparative dentin.This result suggests that marilin-4 may be used as a new type of pulp capping agent,alone or in combination with Ca(OH)2 or MTA,to improve the inadequacies of existing capping agents,and to provide a theoretical basis for the development of superior performance of the pulp capping agent.