Análise da neoformação tecidual e de marcadores da inflamação e de dentinogênese em procedimento endodôntico regenerativo com ou sem uso de fibrina rica em plaquetas injetável em ratos imunossuprimidos

Abstract

The regenerative endodontic procedure (REP) aims to restore the formative, immunological, and defensive properties of the dentin-pulp complex in immature permanent teeth with necrotic pulp. It works by inducing a blood clot within the root canal, which brings stem cells from the periapical region and growth factors to promote the formation of new tissue. However, systemic conditions such as immunosuppression can impair this tissue regeneration process. This study analyzed tissue neoformation, mineralized tissue formation, and immunolabeling for dentin sialophosphoprotein (DSPP) and interleukin (IL)-1β in immunosuppressed rats after REP, with or without the use of injectable platelet-rich fibrin (iPRF). Twenty-four rats were divided into immunosuppressed and non-immunosuppressed groups (cyclophosphamide; 50 mg/kg). The animals were then allocated into four groups (n=6): REP, immunosuppressed REP (IM-REP), REP with iPRF (REP-iPRF), and immunosuppressed REP with iPRF (IM-REP-iPRF). After pulp necrosis induction, root canals were disinfected using 2.5% sodium hypochlorite and 17% EDTA, followed by intracanal medication (ICM). After 15 days, ICM was removed and intracanal bleeding was induced by overinstrumentation with a #10 K-file; in the REPiPRF and IM-REP-iPRF groups, iPRF was inserted into the root canal before bleeding induction. The molars were sealed, and after 21 days, the animals were euthanized and specimens collected for histological (hematoxylin-eosin) and immunohistochemical analyses. Statistical tests were applied (p<0.05). The REP group showed connective tissue neoformation within the root canals extending to the middle and cervical thirds; the REP-iPRF group to the cervical third; and IM-REP and IM-REP-iPRF showed tissue neoformation only in the apical third, with a significant difference between REP and IM-REP (p<0.05). Specimens from REP and REP-iPRF groups showed neoformation of mineralized tissue in both length and thickness of the root canal; most IM-REP and IM-REP-iPRF specimens showed mineralized tissue formation in either length or thickness, or none, with a significant difference between REP-iPRF and IM-REP-iPRF groups (p<0.05). Most specimens from REP and REPiPRF showed moderate immunolabeling for DSPP; in IM-REP and IM-REP-iPRF, almost all specimens also showed moderate labeling, with no significant difference among the groups (p>0.05). All groups showed low immunolabeling for IL-1β (p>0.05). It can be concluded that immunosuppression negatively affected tissue neoformation within the root canals and the formation of mineralized tissue in immature rat molars after REP, but did not influence the presence of DSPP or IL-1β; furthermore, the use of iPRF did not affect the outcomes observed.