Avaliação da perda de estrutura e formação de microtrincas na dentina radicular após diferentes tratamentos mecanizados e soluções irrigantes: análise por microtomografia computadorizada

Abstract

The aim of this study was to evaluate the loss of structure and the formation of microcracks in root dentin after endodontic treatment with different mechanized instrumentation techniques and auxiliary irrigating chemical substance. For this ex vivo laboratory study, 40 (forty) single-rooted lower premolar teeth, Vertucci Class I, with straight roots were selected. The anatomical crowns of the selected teeth were removed with a double diamond disc to obtain a root remnant measuring 15 mm in length from the root apex. The samples were divided into 4 groups (n=10) according to the instrumentation system and auxiliary irrigating chemical substance, they are: 1. reciprocating regressive taper technique + 5.25% sodium hypochlorite; 2. reciprocating regressive taper technique + 2% chlorhexidine; 3. continuous taper reciprocating technique + 5.25% sodium hypochlorite; 4. continuous taper reciprocating technique + 2% chlorhexidine. The roots were scanned using a microtomography computer (SkyScan 1173 – Bruker, Kontich, Belgium) to check the initial and final (posttreatment) volume (mm3) of the root canals and determine the percentage of dentin removed. Two blinded evaluators analyzed cross-sectional images of the roots to identify the presence of dentin microcracks. Data on the amount of dentin removed were collected and subjected to analysis of Homogeneity of Variances (Levine's Test) and Normality Test (Shapiro-Wilk Test). They were then analyzed using the two-way ANOVA test. For all tests, a significance level of 5% was considered. The presence of microcracks was qualitatively analyzed. The two-factor ANOVA test did not demonstrate statistical significance for the results of mechanical preparation (p=0.229), auxiliary chemical solution (p=0.795) and for the correlation between mechanical preparation and auxiliary chemical solution (p=0.395). Analyzes of 29,646 crosssectional images of root canals were carried out and the formation of new microcracks in the dentin of the root canals was not observed for any of the instruments evaluated. Instrumentation of the root canals with reciprocating regressive or continuous taper files and their irrigation with 5.25% sodium hypochlorite or 2% chlorhexidine did not influence the amount of dentin removed and did not create new microcracks in the dentin of the root canals.