Effect Of Dentin Cells And Microvessel Capping The Direct Pulp Of Nano Hydroxyapatite/Polyamide 66

Objective:To investgate and compare the changes of reparative dentin and pulp micro vessel after the indrect capping of nHA-PA66,nHA and CH on molars of Wistar rats 7 days and 30 days.Methods: 84 teeth of the first or second molars were selected as the research object from 12 Wistar rats.7 d and 30 d were two test cycle.84 teeth randomly divided into nano hydroxyapatite / polyamide 66 composite group(NHA PA66),nano hydroxyapatite group(NHA)and calcium hydroxide group(CH).Under sterile conditions,we prepared Class?cavities on the teeth until the pulp was exposed.nHA-PA66,nHA and CH were used as indrect capping materials.These animal were killed after 7d and 30 d.All the teeth were made Chinese ink perfusion,fixed,decalcified,paraffin embedded and serial sections.5um section slice could observe dentin cells by hematoxylin eosin staining and 100 um section slice could observe the changes of pulp blood vessel.Results:7 d after operation: nano hydroxyapatite / polyamide 66 compound group showed in experimental area tissue necrosis and neutrophile granulocyte infiltration,dentinal cell hyperplasia around necrosis area,dilation of blood vessels along the dentin wall;nano hydroxyapatite group showed tissue necrosis,neutrophile granulocyte infiltration and dilation of blood vesselsin experimental area;calcium hydroxide group showed most pulp tissue in pulp chamber necrosis,fibroblasts hyperplasia significantly below necrosis,neutrophil infiltration,a part of vascular necrosis.30 d after operation: nano hydroxyapatite / polyamide 66 composite group showed experimental zone below into dentin cell hyperplasia were stratified,around the tooth essence thickened,dental pulp fibroblasts hyperplasia,dentin cells increased,the dilation of blood vessels;nano hydroxyapatite group showed predentin partly were thickened,dilation of blood vessels obviously,sparse;calcium hydroxide group wore pith cavity under the dental surface agglomerate necrosis,and normal tissue clear boundaries,a large number of neutrophils infiltration,necrosis area beneath dense blood.The results showed that the nano hydroxyapatite polyamide 66 composite had the effect on induce the regeneration of the dentin cells and the stimulation to the pulp blood vessel was small.Conclusion: nano hydroxyapatite / polyamide 66 as pulp capping agents on dentin cells inducing ability was stronger than that of nano hydroxyapatite;the effect on vascular dilatation of nano hydroxyapatite / polyamide 66 pulp capping material was less than that of nano hydroxyapatite.