Comparação de diferentes técnicas de retratamento endodôntico em molares superiores: estudo ex vivo comtomografia computadorizada de feixe cônico

Abstract

Instrumentation of the root canal system is one of the most important steps in endodontic treatment. Failures in this step or in other phases may lead to treatment failure. During this procedure, proper deobturation is essential, and as much remaining primary material as possible should be removed. The aim of this study was to compare the effectiveness of two mechanized instrumentation techniques, with and without the use of solvent, in the removal of filling material from upper molars using Cone Beam Computed Tomography (CBCT). Forty extracted human upper molars were endodontically treated and submitted to CBCT examinations. The teeth were retracted using two mechanized systems (ProTaper-R - PR Group and WaveOne Gold - WG Group), with and without the aid of eucalyptol solvent, and were then reinstrumented and tomographically scanned again. The CBCT examinations were evaluated qualitatively by two dentists regarding satisfactory and unsatisfactory deobturation. Cases classified as unsatisfactory were evaluated according to the location of the remaining filling material (cervical, middle and/or apical third of the root and root: mesiobuccal 1, mesiobuccal 2, distobuccal and palatine). Statistical analysis was performed using means and deviations or medians and interquartile ranges for continuous variables. For categorical variables, absolute or relative frequencies were used. Mixed logistic regression models and mixed linear models were used to verify the associations between the variables. A 5% significance level was considered. The analyses were conducted with the aid of the R software. The results showed that of the 40 molars evaluated, thirteen (33.3%) had 4 canals (MV, MV2, P and DV) and 26 (66.7%) had 3 canals (MV, P and DV). 64% of the canals had remaining filling material, with a higher incidence in the DV canal (77%). In the PR group, the chance of having remaining material without the use of solvent was 3.30 times greater than the chance of having remaining material with the use of solvent. For the WG group, the effect was not significant. The interaction (solvent * file * location) indicated similarity of the effects of solvent and file between the canals (p = 0.4951). The incidence of remaining material per root third and canal was higher in the apical third (62%) and DV canal, respectively. There was no association between MAR and different values of volumes, solvent and file. In a single model, the interaction between the three variables (MAR, volume and solvent) was significant only for the total volume and the significant term was between file and solvent. The effect of the solvent on the identification of the volume depended on the file used. In a multiple model, the effect of the solvent contrast on the total volume appeared when the ProTaper-R file was used. It was concluded that the quality of the removal of filling material in retracted upper molars was better when the Wave One Gold R25 system was used. The aid of eucalyptol solvent contributed to facilitate root canal unblocking when the ProTaper-R file was used. There was no significant difference when the tool for metal artifact reduction (MAR) was used.