Animal Experiment Study Of Platelet-rich Fibrin (PRF) Applied To Direct Pulp Capping

ObjectiveIn recent years, researchers are aiming at researching that how toconduct the vital pulp conservation treatment successfully. As ourkonwing of endodontacal biology researching progress and of thereparative dentine formation become more and more deeper,many pulpcapping materials come into view,such as MTA, calcium hydroxide,bone morphogenetic protein and so on. Each of them has bothsuperiority and inferiority, an ideal material is still expected.It is the key to success that reparative dentin form under the pulpcapping materials. When stimulation occurs,precursor cells in pulpmigrate, proliferate and differentiate into odontoblast-like cells, whichsecreting dentin matrix,then the mineralization occurs and the injuredpulp is repaired by reparative dentin[9]. Biological factors plays animportant role in this procedure.Researchers intend to carry out the vitalpulp therapy with growth factors singly by imitating the physiologicalrepairing procedure of human dental pulp[10]. Therefore,in thisexperiment,we chose PRF as pulp capping material. PRF containsnumerous growth factors, blood platelet and leukocytes,such asPDGF-AB, TGF-β1, VEGF, IGF, EGF and so on,they will be slowly released when α-grains in blood platelet are activated[11].Choukroun’sstudies have shown that PRF can promote the angiogenesis,woundhealing procedure,also, it has the property of anti-inflammatory andanti-infective[12]. Other studies showed that PRF could promote theproliferation and differentiation of dental pulp cells, increase theexpression of OPG and the activation of ALP[7]. Additionally, PRFretrieved form autologous blood by once centrifugation, withoutartificial agents, which insure the safety,cheapnessand simpleness.In this experiment, we used PRF/Dycal,PRF,Dycal as pulp cappingmaterials to carry out the direct pulp capping therapy on rabbits incisors,and observed the reparative dentin degree and pulpinflammation.Also,the feasibility of PRF as pulp capping material andthe most suitable application had been explored.MethodsThe experiment was conducted on42maxillary incisors of22healthy domestic rabbits which were divided into PRF/Dycal group、Dycal group and PRF group randomly. There are two periods:5days and10days,and7tooth each group. Under sterile conditions,we preparedcavities mechanically on the teeth until the pulp was exposed.PRF/Dycal、Dycal and PRF were applied as direct capping agents. Thenall cavities were filled with glass ionomer.Domestic rabbits weresacrificed at5days and10days after operation. After routine histological preparation, sections were stained with haematoxylin andeosin(HE). Samples were histologically evaluated for the degree ofinflammation and reparative dentine formation.Finally the data wasanalyzed by Chi-Square tests through SPSS17.0. The statisticalsignificant level was selected at p<0.05.Results5days after operation, the result showed that PRF/Dycalgroup、Dycal group and PRF group had no reparative dentine bridgesand PRF/Dycal group and Dycal group had some reparative dentinecalcifications,while PRF group did not form any reparativedentine.There was no significant difference between PRF/Dycal groupand Dycal group（P＞0.05). However, PRF group was significantlydifferent with the other groups（P＜0.05).From the pulp inflammation ofthree groups,we could observed that PRF group had milderinflammation than the other two groups, however, this three groups hadno statistical difference（P＞0.05).10days after operation,the result displayed that most of PRF/Dycalgroup and Dycal group formed reparative dentine bridges andcalcifications, and PRF/Dycal group was better than Dycalgroup, andthere was significant difference in these two groups（P＜0.05).PRFgroup formed little calcifications, and it was significant different withthe other groups（P＜0．05). We could find that compared with the othertwo groups, PRF/Dycal group had slighter inflammation or even no inflammation, and the difference was significant（P＜0.05). At the sametime, Dycal group and PRF group had no statistical differences（P＞0.05).ConclusionFrom the degree of reparative dentine, we can conclude thatcombinating application of PRF and Dycal could more benefitpromoting the repair of injured pulp, also could induce reparativedentine better. At the same time, when Dycal or PRF was applicatedseparately, both of them were far from the effect above. And from thecondition of pulpitis, combinating application of PRF and Dycalexhibited better anti-inflammation and regulation effects than Dycal wasapplicated alone. Combinating application of PRF and Dycal as a pulpcapping agent maybe better for promoting the repair injured pulp.