Geometric Analysis of Curved Canals Prepared by HyFlex EDM Versus HyFlex CM Rotary Nickel Titanium Files: An In-Vitro Study
Mohamed Moftah Mohamed1*, Shaimaa Ismail Gawdat2 and Reem A Lutfy3
1MSD Endodontic, Faculty of Dentistry, Cairo University, Egypt
2Associate Professor of Endodontics, Department of Endodontics, Faculty of Dentistry, Cairo University, Egypt
3Professor of Endodontics, Department of Endodontics, Faculty of Dentistry, Cairo University, Egypt
*Corresponding Author: Mohamed Moftah Mohamed, Masters Student, Faculty of Dentistry, Cairo University, Egypt and Shaimaa Ismail Gawdat, Associate Professor of Endodontics, Department of Endodontics, Faculty of Dentistry, Cairo University, Egypt.
Received: April 08, 2021; Published: May 29, 2021
Objective: The aim of this study was to compare and evaluate 2 file systems: HyFlex EDM and HyFlex CM in preparing severely curved mesiobuccal canals of human mandibular molars regarding: the centering ability, transportation of the canal and ability to maintain canal radius of curvature, utilizing cone beam computed tomography (CBCT).
Materials and Methods: A sum of thirty mesiobuccal root canals of extracted human mandibular molars having angle of curvature ranging from 25 - 45 ͦ (according to Schneider) were selected and assigned into two groups; HyFlex EDM and HyFlex CM. The distal roots with the respective part of the crowns of all samples were sectioned and discarded after access cavities preparation and working length determination. Samples were mounted in two molds of acrylic resin for pre and post-instrumentation imaging utilizing CBCT. Root canal preparation was done by each NiTi system according to the manufacturers' instructions. The CBCT images at the root canal levels (3, 5 and 8 mm from the tooth apex) were superimposed using a fusion module of OnDemand 3D App software for dentin thickness measurement. Ability to maintain canal radius of curvature was recorded following Estrela., et al. while canal transportation and centering ability were recorded following a formula introduced by Gambill., et al. Data was tabulated and statistically analyzed.
Statistical Analysis: Data was tabulated and statistically analyzed; Independent samples t-test was used for comparing the change in the radius of canal curvature angle between the two groups and also was used for comparing the variables between the two groups at each root canal level. The significance level is considered at P ≤ 0.05.
Results: The HyFlex EDM recorded statistically lower mean value at the 5 mm level, while at the 8 mm level it recorded statistically higher mean value of root canal transportation than HyFlex CM. There was no statistically significant difference regarding direction of root canal transportation and centering ability between the two rotary systems. Concerning the ability to maintain canal radius of curvature, a statistically significant difference was found between pre and post radii of curvature for each file system, but no significant difference was found between the two systems.
Conclusion: Under the limitations of this in vitro study, it can be concluded that; HyFlex EDM and HyFlex CM systems were relatively safe in preparation of curved root canals and were not able to achieve perfect centering ability during root canal preparation. HyFlex CM has shown more straightening regarding the radius of curvature.
Keywords: Canal Transportation; Centering Ability; Canal Radius of Curvature; HyFlex EDM; HyFlex CM; CBCT
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