Development and analysis of new irrigators and protocols for use in revascularization and pulp regeneration procedures

Abstract

Regenerative endodontic procedures are indicated for the treatment of necrotic immature teeth by allowing root development, resulting in increased root length, thickness and apical closure. To be effective, the disinfection of the environment is a prerequisite and the elimination of the instrumentation stage hinders the debridement that is performed only by chemical solutions. The associated use of low concentrations of sodium hypochlorite (NaOCl) and tetraacetic ethylenediamino acid (EDTA) at 17% has been recommended for cleaning and disinfection of necrotic immature tooth canals. However, studies show that NaOCl causes deleterious effects on stem cells and the dentin matrix. As a result, the objective of this research will be to evaluate, in vitro, the use of Ambroxol Hydrochloride at different concentrations, alone or associated with different irrigating solutions and when ultrasonic or laser activation is used, evaluating the following: 1) Cytotoxicity, proliferation and vitality in dental papilla stem cells; 2) Antimicrobial and antibiofilm action; 3) Ultrastructural effects on dentin; 4) Apical tissue dissolution capacity. For all tests performed, the specimens will be divided into 13 groups (G1-G13), according to the irrigation protocol and subdivided according to the irrigation method (n=3): Conventional irrigation with syringe and needle (SG1), ultrasonic agitation (SG2), agitation with Laser Thera Lase Surgery (SG3). For cytotoxicity, proliferation and vitality and tissue dissolution tests, root dentin cylinders will be prepared to simulate root canals of teeth with incomplete rhizogenesis, which will be positioned in close contact with a three-dimensional (3D) culture of SCAPs or with bovine muscle tissue, simulating the clinical environment. For antimicrobial capacity assessment, 10 bovine canines per group will be selected and prepared for antimicrobial tests in dentinal tubules and antibiofilm of Enterococcus faecalis, Eikenella Corrodens and Streptococcus anginosus. To evaluate the ultrastructural effects on dentin, a prototyped tooth will be made from the scan in computerized microtograph (micro-CT) and with the aid of a trefina, a site will be created for the fitting of bovine dentin blocks. Then, the irrigation protocols will be performed using a closed system and the amide III/phosphate and carbonate/phosphate (PO3-)/(CO3-) ratio will be determined with FTIR analysis and scanning electron microscope images will be made. The Shapiro-Wilk normality test and then the parametric or nonparametric test will be applied, and 5% will be adopted as a significance level. (AU)