A influência da aplicação da endodontia minimamente invasiva na descontaminação e modelagem de incisivos inferiores hígidos

Abstract

The main goal of minimally invasive endodontics is to preserve as much of the dental structure during treatment root canal. The present study intends to evaluate the influence of the taper and of the tip of the endodontic instruments on the decontamination and on the ability to shape root canals of mandibular incisor with incisal access. Seventy teeth were scanned via microcomputed tomography to analyze their initial internal anatomy, surface area (mm²) and volume (mm³) with the goal of assembling homogenous groups of three specimens. Forty mandibular incisors were divided in three experimental groups (n=10 in each group) and two control group (positive and negative; n=5 in each group). Subsequently, the incisal coronal access was performed. The samples were, then, contaminated with bacterial suspensions of Enterococcus faecalis. Following the three-week period, the initial microbial sampling was performed (S1) in all experimental groups. The chemical-mechanical preparation was performed out according to the experimental group, as follows: Group 1: preparation with the Univy 25/02 instrument, Grupo 2: preparation with the TruNatomy 26/04 instrument and Grupo 3: preparation with the Univy instrument 35/04. After using these instruments, the second microbiological sample (S2) was performed out in all experimental groups according to S1. After the use of each instrument, the root canal was irrigated with 1 mL of 0.5% NaOCl. Then, all specimens received a final irrigation protocol using 2 mL of 0.5% NaOCl, 2 mL of 17% EDTA and 2 mL of 0,5% NaOCl. Next, a new microbiological sample was peformed (S3). To neutralize NaOCl before microbiological sampling 1 mL of saline, 2.5 mL of 10% sodium thiosulfate and 1 mL of saline were used. The total volume of irrigating solution used was 21 mL per canal. After the instrumentation and the sample S3, the teeth were rescanned and the percentage of unprepared walls and the volume of dentin removed were evaluated. The statistical analysis was performed with adjustments of the type I negative binomial regression model as well as the beta regression model with a 0-1 inflation. Testing of instrumentation results was performed by means of the Kruskal-Wallis and ANOVA. The results showed that no discrepancies in the percentage of unprepared surface in the removal of dentin (P>0.05). In microbial reduction, the larger values of bacterial counts were found in group 1 in the samples S2 and S3 when compered to the other groups (p<0,05). In S3, there was also a significant difference between groups 2 and 3, with group 2 having a higher microbial count (p<0.05). Regarding the percentage of the microbial reduction there was no significant difference between groups (p>0,05). It was concluded that the application of conservative 25.02 (G1) presented losses in relation disinfection of the SCR compered to conventional preparations.