Effect of poly(aspartic acid) associated with mineral trioxide aggregate (MTA) on dentin regeneration in rat molars

Author(s)

Fernanda Furuse Ventura dos Santos

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Odontologia (FO/SDO)
• Defense date: 2023-02-08

Examining board members

Roberto Ruggiero Braga; Letícia Cristina Cidreira Boaro; Fabio Dupart Nascimento; Marcelo dos Santos

• Advisor: Roberto Ruggiero Braga

Abstract

Recently, it was demonstrated that a non-collagenous protein analog was able to guide the mineralization of a collagen scaffold and induce stem cell differentiation in osteoblasts, leading to the formation of a tissue similar to native bone (Thrivikraman et al., Nat Commun 2019). Thus, despite the good results achieved with calcium silicate (mineral trioxide aggregate, MTA) and Ca(OH)2 cements in pulp exposure cases, it is possible that biomimetic analogs stimulate dentin regeneration through greater differentiation of pulp stem cells into odontoblasts and guided mineralization of the dentin matrix, resulting in the formation of a reparative dentin with superior histological characteristics to that found with the use of Ca(OH)2 and MTA and in less time. The aim of this study was to verify whether the use of a biomimetic analog (polyaspartic acid, pAsp) associated with MTA would provide superior results to pulp capping with MTA only. Wistar rats (N=56) were divided into two groups, according to the postoperative period (7 and 21 days) and treatment. Under general anesthesia, mechanical pulp exposure of the occlusal surface of the first maxillary molars were performed followed by one of the treatments (randomly defined, n=7): C Group (negative control) - only sealing the cavity with flowable resin composite; MTA Group (positive control) - pulp capping with MTA and cavity sealing with flowable resin composite; pAsp Group - application of 20 L of pAsp solution and sealing the cavity with flowable resin composite; MTA / pAsp Group - application of MTA mixed with pAsp solution in the ratio of 5:1 (by mass) and sealing the cavity with flowable resin composite. After euthanasia and processing of the hemimaxillas, the secctions were submitted to histopathological analysis (HE staining and Brown and Brenn staining modified by Taylor) and immunohistochemical analysis to detect Dentin Sialoprotein (DSP), Nestin, Osteopontin (OPN) and Dentin Matrix Protein 1 (DMP-1). At 7 days, the presence of acute inflammatory infiltrate and formation of disorganized mineralized tissue was observed in all groups. The quality and thickness of the reparative dentin formed at 21 days in the treated groups was superior to that found in the control group. There was bacterial contamination only in some specimens isolated in the MTA-pAsp group at 21 days. Immunostaining for both DMP-1 and OPN was higher in the treated groups when compared to the control group in both periods, and the pAsp group showed a superior ability to express OPN than the other groups. Immunistochemical reactions for the detection of DSP and nestin did not show positive immunostaining. The use of poly(aspartic) acid in dentin regeneration in rats proved to be an alternative as effective as the isolated use of MTA in direct pulp capping. (AU)

• FAPESP's process: 20/10208-1 - Effect of polyaspartic acid on dentin regeneration in rat molars
• Grantee: Fernanda Furuse Ventura dos Santos
• Support Opportunities: Scholarships in Brazil - Master