| Objective:In this study,PRF membrane combined with MTA was used as a new compound pulp capping agent for direct pulp capping of central mandibular incisor in rabbits.The pulp inflammatory reaction and hard tissue formation after direct pulp capping of experimental teeth were observed,and the feasibility of PRF as direct pulp capping material was discussed to provide more optimized plans for the selection of clinical pulp capping agent.Methods:1.Thirty-two healthy New Zealand rabbits which had passed the quality test of Guangxi's experimental animals were half male and half male,weighing 2.5-3 kg.2.Experimental methods:(1)Experimental grouping: 32 New Zealand rabbits were randomly divided into 4 groups with 8 experimental rabbits in each group.2 central mandibular incisors of each rabbit were used as experimental teeth and received the same treatment.According to the different capping materials,they were divided into three experimental groups(PRF+MTA group,MTA group,PRF group)and blank control group.(2)Establishment the dental pulp exposure model in animal experiments: under the condition of general anesthesia with sodium pentobarbital,the gingiva of the mandibular incisor was cut open,the flap was turned,the experimental teeth were fully exposed,and the pulp was mechanically exposed.(3)Direct pulp capping:the pulp capping materials were used in different groups for direct pith capping.3.Sample collection and measurement:(1)The experimental teeth were filmed with CBCT immediately before and after surgery,on the 7th and 28 th day,and Mimics19.0 software was usedto conduct reconstruction of the experimental teeth and calculate the volume of the dentine bridge formed at the perforating pulp hole.(2)Four experimental rabbits were randomly selected from each group and sacrificed on the 7th and 28 th day after the operation,respectively.The lower jaws were separated,the soft tissues were removed,and 4% para-formaldehyde solution was fixed.The experimental teeth were separated one by one,put into 14%EDTA solution for decalcification,followed by hematoxylin-eosinstaining(HE)staining.The pulp inflammatory reaction and dentine bridge formation were observed under light microscope,and then graded.4.Data processing: the volume of dentine bridge was analyzed by one-way analysis of variance with SPSS20.0,and the rank sum test was conducted for the histology grade of dental pulp.Results:1.Radiographic results:(1)7th day after surgery: the dentine bridge volumes in the three experimental groups were all larger than those in the blank control group,with statistically significant differences(P<0.05),but there was no significant difference among the three experimental groups(P>0.05);(2)28th day after surgery: the dentine bridge volume of PRF+MTA group was larger than that of PRF group and blank control group(P<0.05),but there was no statistically significant difference between the PRF+MTA group and MTA group(P>0.05).2.HE results:(1)Pulp inflammatory reaction:7th day after surgery: the pulp inflammation in PRF+MTA group was milder than that in PRF group and blank control group,and the difference was statistically significant(P<0.05),but there was no statistically significant difference in the degree of pulp inflammation between PRF+MTA group and MTA group(P>0.05),there was no statistically significant difference in the degree of pulp inflammation between PRF group and blank control group(P>0.05).28th day after surgery: the pulp inflammation in PRF+MTA group was milder than that in PRF group and blank control group,and the difference was statistically significant(P<0.05),but there was no statistically significant difference in the degree of pulp inflammation between PRF+MTA group and MTA group(P>0.05),there was no statistically significant difference in the degree of pulp inflammation between PRF group and blank control group(P>0.05).(2)Reparative dentin or hard tissue formation:7th day after surgery: PRF+MTA group had a higher degree of formation of repaired dentin or hard tissue than PRF group and blank control group,and the difference was statistically significant(P<0.05),but there was no statistically significant difference in the formation of repaired dentin or hard tissue between PRF+MTA group and MTA group(P>0.05).28th day after surgery: The blank control group had a lower degree of repair dentin or hard tissue formation than the other three experimental groups,and the difference was statistically significant(P<0.05),PRF+MTA group had a higher degree of repair dentin or hard tissue formation than MTA group and PRF group,and the difference was statistically significant(P<0.05).Conclusion:1.When PRF is used alone as a pulp capping agent,pulp tissue has a strong ability to form restorative dentin or hard tissue,but the pulp inflammatory response is stronger.2.When PRF+MTA is used for direct pulp capping,the response of pulp inflammation is similar to that of MTA,which has a certain inhibitory effect on inflammation.3.When PRF+MTA is used for direct pulp capping,but the ability of pulp tissue to form repaired dentin or hard tissue is stronger than that of MTA,and the hard tissue formed is dominated by osteodentin. |
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