Date of Graduation

2017

Document Type

Thesis

Degree Type

MS

College

School of Dentistry

Department

Orthodontics

Committee Chair

Elizabeth Kao

Committee Co-Chair

Jerry Bouquot

Committee Member

Keith Hildebrand

Committee Member

Bryan Weaver

Abstract

Introduction: The aim of this study was to evaluate the efficacy of two new to the market 3-dimensional serpentine shaped nickel titanium rotary files, XP Shaper and TRUShape, as primary retreatment files for the removal of filling of material from mesial roots of mandibular first molars filled with bioceramic sealer and two different types of gutta percha, bioceramic coated and traditional non-coated cones.;Materials and methods: 40 mesial roots of mandibular first molars were prepared and divided into four groups (n = 10). 20 specimens were obturated with single cones of traditional non-coated gutta percha (TGP), EndoSequence Gutta Percha, and 20 specimens were obturated with bioceramic coated single cones (BC), EndoSequence BC Points. Both were sealed with a bioceramic sealer, EndoSequence BC Sealer. Removal of the obturated and sealed gutta percha from the root canals were performed by either the TRUShape (TS) or XP Shaper (XP) files. The efficacy of filling material removal was examined using a micro-computed tomographic scanner. Mean percentages of volume and surface area remaining after the retreatment procedure were analyzed using the Kruskal-Wallis and Mann-Whitney U tests. Canal patency and their correlation with the files and gutta percha were analyzed using Pearson's chi-square test. All tests were set at a significance level of (p = 0.05).;Results: The mean percentage volume and surface area of remaining filling material was significantly different (p < 0.05), among all groups tested. The use of XP files in removing BC coated cones, resulted in canals with a mean percentages of 33.98 +/- 5.28% volume and 61.97 +/- 7.17% surface area of residual material which were significantly different than all the other groups, (p < 0.05). Significant differences were found in the mean percentage of volume and surface area of remaining material when comparing the efficacy of XP to TS for (p < 0.05), independent of the type of gutta percha used. Finally, there was a significant association between the type of gutta percha used and canal patency (p < 0.05); teeth obturated with TGP cones achieved 65% canal patency compared to 25% in those obturated with BC cones. There appears to be a strong correlation between the type of file used and canal patency (p = 0.0565) with 60% of the TS group regaining canal patency compared to 30% in the XP group.;Conclusion: Neither of the 3D motion files tested were able to successfully remove 100% filling material from the canals nor regain 100% canal patency. However, the TS instrument was found to remove significantly more material independent of the gutta percha used and establish canal patency in 60% of the roots retreated. Teeth obturated with traditional gutta percha regained canal patency better than those obturated with bioceramic coated gutta percha. The results of this study show that the use of a bioceramic sealer especially in combination with a bioceramic coated gutta percha may make regaining canal patency more difficult.

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