Animal Experimental Study Of The Anti-inflammatory Effect Of TIMP-1 In Irreversible Pulpitis

Objective A model of partially irreversible pulpitis was established in SD(Sprague Dawley)rats,and the tissue inhibitor of metalloprotease(TIMP-1)was applied during pulpotomy.The anti-inflammatory effect of TIMP-1 was investigated by histological and immunohistochemical analysis in the treatment of partially irreversible pulpitis with vital pulp therapy(VPT).Methods1.Establishment of partial irreversible pulpitis modelBilateral maxillary first molars of 8-10 weeks old male SD rats were selected as experimental teeth,and the pulp cavities were exposed for 6 h,12 h,24 h,36 h,48 h and 72 h to construct a model of irreversible pulpitis with different degrees of inflammation.The duration of pulp exposure(24h,36h,48h)was selected for follow-up experiments based on HE(Hematoxylin-Eosin)sections with histopathological manifestations of typical partially irreversible pulpitis.2.VPT of partial irreversible pulpitisAfter the pulp cavity was exposed for 24h,36h and 48h,and the partially irreversible pulpitis model was successfully established,the crown pulp was abraded and pulpotomy was performed,and TIMP-1 was given to the experimental group and normal saline(NS)to the control group after pulpotomy.Histological and immunohistochemical observations were performed on maxillary first molars 24 and 48 hours after the administration of the drug.:HE staining was performed to observe the histopathological changes(inflammatory cell reaction in the root pulp,morphological changes in the root pulp tissue,extent of root pulp necrosis)in the remaining root pulp tissue after pulpotomy with TIMP-1/NS treatment and to perform quantitative histological analysis;IHC(Immunohistochemistry)staining(immunofluorescent CD68 labeling)to observe the expression of CD68-positive cells in the remaining root pulp tissue of rat molar teeth after pulpotomy.Results1.The quantitative histopathological analysis of HE-stained sections showed that the drug(TIMP-1/NS),the length of pulp exposed,and the duration of drug administration had a significant effect on the inflammatory histological status of the root pulp(root pulp inflammatory cell response,root pulp tissue morphological changes,and extent of root pulp necrosis),and the inflammation score was significantly higher in the TIMP-1 group compared with the NS group and increased with increasing length of pulp exposed and duration of drug administration(P<0.05).2.Immunohistochemically stained(CD68-labeled)sections showed that the expression of CD68-positive cells was significantly more in the TIMP-1 group than in the NS group,and the expression of CD68-positive cells increased with the increase in the length of pulp exposed and the length of drug administration,in accordance with the histological scoring results(P<0.05).Conculsion1.The use of TIMP-1 in vital pulp therapy of partially irreversible pulpitis aggravated the progression of root pulp inflammation,and TIMP-1 had no anti-inflammatory effect.2.The inflammatory condition of the root pulp increased with the length of pulp exposed and the length of drug administration,and TIMP-1 had no anti-inflammatory effect in various degrees of pulpitis.