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Analysis of rotating and reciprocating systems with different alloys in the removal procedure in endodontic retreatment

Grant number: 15/08911-8
Support type:Scholarships in Brazil - Doctorate
Effective date (Start): August 01, 2015
Effective date (End): November 30, 2016
Field of knowledge:Health Sciences - Dentistry - Endodontics
Principal researcher:Marco Antonio Hungaro Duarte
Grantee:Amanda Garcia Alves Maliza
Home Institution: Faculdade de Odontologia de Bauru (FOB). Universidade de São Paulo (USP). Bauru , SP, Brazil

Abstract

The main goal of endodontic therapy is clean, shape, eliminate the infection and fill in three dimensions the root canal system to prevent recontamination. However, even reaching those goals, failures can occur in endodontic treatment, leading to the need for a retreatment, when indicated. This study consists to evaluate the effects from the removal of root canal filling material, canals reinstrumentation and reobturation, with different NiTi alloys in cases of endodontic retreatment. First, an anatomical study will be done for the selection and pairing of mesial root canals of mandibular first molars (n = 45) by computed microtomography (micro-CT). After pairing the specimens, they will be instrumented with Mtwo® system to file 25.06 and scanned by micro-CT again. The specimens will be filled by a single cone technique using Endofill® sealer plus 0.1% rhodamine B, scanned by micro-CT again and stored at 37ºC with 100% humidity for 7 days. For retreatment of the specimens, 3 groups will be established, according to the system used (Reciproc®, HyFlex® or ProDesign Duo Híbrido®). During the retreatment, the specimens will be scanned by micro-CT for another 2 times in different steps, the first being soon after the removal of root canal filling material, and the second one after the canals reinstrumentation. All the images obtained before and after the retreatment will be compared in order to assess the filling material removal capacity of each system, and to evaluate possible deviations of the root canals. It will be evaluated as well, the effective time of the removal procedure and canals reinstrumentation with different systems, in addition to filling material and debris extruded via foramen during the removal procedure and reinstrumentation respectively, which are calculated volumetrically. After this, the root canals will be reobturated with the same technique as described, but with AH Plus® sealer plus 0.1% fluorescein and stored again at 37°C with 100% humidity for 7 days. After the proposed time, the specimens will be cut crosswise into Isomet machine, resulting in 2mm slices, to be analyzed in laser scanning confocal microscope (CLSM) at 2, 4 and 6 mm from the apex, where it will be evaluated, through LAS X 3D e 2D software, the total perimeter of the root canal, the length of old filling material and the depth of penetration into the dentinal tubules of the old sealer remaining. To determine the appropriate statistical test, the data obtained in each analysis will be submitted to D'Agostino and Pearson normality test, which will be adopted the 5% significance level. (AU)

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