Pulp Revascularization:A Clinical Retrospective Study And Histologic Finding Of Canine Pulpless Teeth

Objectives1 To evaluate the clinical efficacy and relevant factors of root development and calcification in the treatment of immature young permanent teeth with or without periodontitis by reviewing the cases of pulp revascularization in our hospital.2 To examine the tissues generated within the root canals by using blood clots and blood clots mixed with platelet-rich fibers(PRF)as scaffolds in revascularization under ideal conditions in a cannie model.3 To further explored the histological basis,influencing factors and mechanism of pulp revascularization combined the clincal and animal studies.Methods1 According to the inclusion criteria,25 patients,during 2016-2019,with or without periodontitis who were treating with revascularization were selected.Record the detailed informations including basic information(Age,sex,etiology,degree of root development,apical foramen size,periapical lesions);therapeutic regimen(irrigants,intracanal medicaments,degree of bleeding,the using of PRF)and outcomes(root development,root canal wall thickening,apical clousre,root development types).Datas were entered into Excel for induction and statistical analysis to summarize the efficacy and clinical factors related to root development and root canal calcification.2 Twelve inciso teeth with apex open from lyoung male dog of 5 months' age was used in this experiment.PRF membrane was prepared by extracting venous blood from the forelimb during the operation.Each root was routinely removed dental pulp,inrrigation,then induced bleeding into root canal.Six teeth were in one group.groupA was just blood in the root canal;group B was additional added PRF membrance,then putting iRoot BP Plus 2mm onto the clot.Sealed each root with resin.Three months after the operation,histological analysis was performed on the types of new tissues in the root canals of the two groups.Results1 The average follow-up time was 15.44(12-30)months,amomg which 21 root canal achieved the increasein root length,20 root canal showed dental wall thickness increased,4 root canal occurred calcification.Five types of responses were observed:type A,continued root maturation(apical foramen closure/narrow);type B,no significant continuation of root development with the root apex becoming closed;type C,severe calcification(obliteration);type D,a hard tissue barrier formed in the canal between the coronal MTA plug and the root apex;typeE,there was no change compared before.The increase of root length was significantly different between the age,degree of bleeding,while there was no statistically significant differences in the size of the root apical,the lesion area around the root apical,and the stage of root development.Since only 5 cases were treated with PRF,no correlation was found between PRF and root development.Meanwhile,we cannot find the related clinical factors between thr root Calcification.2 Nine of 12 teeth were completely extracted after 3 months.All teeth showed apical closed and dental wall thickness.5 sections of 9 teeth with homogeneous HE staining in the two groups showed different degree pulp-like tissue regeneration.The tissues ingrowth the root canal were much more similar with the tissue formed after pulpotomy.Among the blood clot group,there are much more osteodetin islands formation in one tooth canal slide,and one slide of PRF group can be seen the formation of cementum-like tissue near the apical but not ingrowth the root canal.Due to the small number of observable samples,we can not find the differences abilities of regeneration between blood clot and PRF group.Conclusions1 Pulp revascularization can promote continuous root development(72.4%).The age and degree of blood induction may be related to the root continuous development.There are no singnificant clinical factors between.the root canla calfication.2 The residual dental pulp tissue in the apical root canal may promote the regeneration of dentin-pulp complex.3 No difference was found between PRF and blood clot in promoting continuous root development and guiding tissue regeneration4 Due to the small sample size in this study and short visting time,the stastistical results may be biased to some extent.Therefore it is necessary to expand the sample size and conduct logistic multivariate regression to evaluate the primary factors related to root development and canal calcification.