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A Computational Analysis of Bending and Torsional Properties of Three Nickel-Titanium Endodontic Instruments with Different Cross-sections

Author: ChenLu
Tutor: WuBuLing；GaoJie
School: Southern Medical University,
Course: Clinical Stomatology
Keywords: Nickel-titanium endodontic instruments Bending properties Torsion properties Cross sectional shape Finite Element Analysis
CLC: R781.05
Type: Master's thesis
Year: 2011
Downloads: 31
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Abstract

The research background nitinol superior superelasticity plus unique cutting edge of the design to make nickel-titanium endodontic instruments by the electric motor curved root canal preparation as ideal continuous taper, and keep the original form of the root canal, but the potential of the instrument broken phenomenon is not uncommon. In recent years, the nickel-titanium endodontic instruments broken influencing factors, different nickel-titanium endodontic instruments bending and torsional performance or anti-cycle fatigue properties of comparative studies of clinical and experimental studies. While these are necessary, but the computer simulation studies as an important supplement and theoretical support for clinical and experimental studies. In fact, computer simulation studies can lead to instrument fracture stress and strain to quantify, but also by changing the model boundary conditions and load status instrument under different conditions of stress and strain conditions, without doping operator influencing factors, and these are Clinical and experimental studies can not be achieved. The impact factors of nickel titanium endodontic instruments broken many, many studies have confirmed that the cross-sectional shape largely determines the mechanical properties of nickel-titanium endodontic instruments, thereby affecting their chances of broken. Therefore, in order to compare the performance of three different cross-sectional shape of the nickel titanium endodontic instruments bending and torsion, to provide reference for clinical rational selection and use of these devices, the study from the perspective of biomechanics using finite element analysis to design and The following experiment was conducted. Purpose Micro-CT scanning technology and Hyperworks 10.0, of three -, ANSYS 12.1 software to create three different cross-sectional shape of the three-dimensional solid and finite element model of nickel titanium endodontic instruments, eight different bending the three-dimensional geometry and finite element model of the root canal. Bending parameters by comparing the same instruments (ProTaper F3, for example) into eight different curved root canals stress distribution study root canal nickel titanium endodontic instruments stress distribution, thus confirming the finite element analysis in understanding nickel titanium endodontic instruments during root canal preparation usefulness of mechanical properties, and is a follow-up experiment to pick out the most dangerous curved root canals and safest curved root canals. On this basis, three different cross-sectional shape of the nickel-titanium root canal instruments analog bending experiments in vitro and simulation clinical curved state under stress distribution compared with the position of its bending properties. Vitro bending experiments to simulate the three instrument tip subject to the same bending displacement; clinical bent state refers to the dynamic process of moving to the apical foramen simulate three instruments in the most dangerous in the curved canal. Second, through three different cross-sectional shape of the nickel-titanium endodontic instruments analog vitro reverse the stress distribution under reverse the status of the experimental and simulated clinical performance compare their reverse. In vitro reverse the experiment the analog the three instrument handle end by the same torque, while clinical reversing the state the analog instrument tip in the safest curved root canal stuck, the handle end is still subject to the process of torque. By analog instruments bending and torsion state of different cross-sectional shape of the mechanical properties of nickel-titanium endodontic instruments, rational selection and use of these nickel-titanium endodontic instruments provide a theoretical guidance for clinical. Materials and Methods Chapter nickel titanium endodontic instruments in three different cross-sectional shape of three-dimensional solid and finite element model, eight curved nickel-titanium root canal geometry and finite element model of the first part of the three different cross-sectional shapes of endodontic instruments dimensional solid and finite element model to choose three different cross-sectional shape of the machine with the nickel-titanium root canal instruments: ProFile.06 / # 30, ProTaper F3 ProTaper Universal F3 scan devices using micro-CT system slice thickness of 14um. Scanning tomographic images three-dimensional reconstruction of the Hyperworks 10.0 Importing IGES format. Tetrahedral element meshing of three-dimensional solid model to obtain a three-dimensional finite element model, unit type is solid 185. Import the file cdb format finite element analysis software ANSYS 12.1 and set nitinol nonlinear material parameters. The second part of the eight kinds of curved root canal geometry and finite element model of the establishment of the complex curved root canals simplify entities tubular structure, including the two basic components of line segments and curved segments. The parameters of the curved section to be determined as the bend angle, bend radius and curved portions. Root canal material parameters are defined as dentin, the inner surface of the root canal is defined as a smooth linear elastic, the total length of 12.9mm, root canal wall thickness of 0.1 mm, root canal diameter than the nickel-titanium endodontic instruments (ProTaper F3 ) width of 0.02mm. Combination of different parameters of bending, the establishment of the eight categories of root canal geometry model in Pro / E 3.0, to import IGES format Hyperworks 10.0, with hexahedral element meshing them to obtain a three-dimensional finite element model, unit type solid185. The file to cdb format import the FEA software ANSYS12.1 set of geometric parameters and material of the root canal. Bending parameters of the second chapter of the root canal of nickel titanium endodontic instruments stress distribution, for example, research ProTaper F3 instruments from the road to the apical root canal port, observation equipment to reach eight different canals instant stress contours most dangerous bend and the maximum von Mises stress, and equipment in eight curved root canal the maximum von Mises stress analysis, evaluation of the root canal bending parameters on the stress distribution of nickel titanium endodontic instruments; selected for follow-up experiments root canal and safest curved root canals. Chapter three different nickel-titanium endodontic instruments bending and torsional properties of a computer simulation study of the cross-sectional shape of the first part of three different cross-sectional shape of the nickel-titanium endodontic instruments bending performance computer simulation study, three nickel-titanium The endodontic instruments handle end cantilever fixed, tip perpendicular to the forced displacement of 3.5mm, loaded as a static load. Observe the Von-mises stress contours, the maximum Von-mises stress and bending moments. 2, the most dangerous curved root canals for the experiment root canal, three different cross-sectional shape of the nickel-titanium root canal instruments from the root canal opening to move the instant contact of the apical foramen. Observed three nickel-titanium endodontic instruments reach the apical foramen instant stress contours and maximum von Mises stress. Reversing the performance of a computer simulation study of the second part of three different cross-sectional shape of the nickel-titanium endodontic instruments, nickel-titanium endodontic instruments tip 3mm fixed the handle the end lend clockwise torsion torque to 2.5Nmm. Load for static loading. Observe the Von-mises stress contours, Von-mises stress and rotation in radians. 2, in the most secure curved root canals for the experiment root canal, three different cross-sectional shape of the nickel-titanium root canal instruments uniform movement from a root canal opening to the apical hole momentary contact, assuming that the instrument tip away from the apical 1mm jammed, the rod the Ministry give 2.5Nmm instant torque. Three nickel-titanium endodontic instruments torsional moment of stress contours and the maximum von Mises stress was observed. Results of this experiment successfully established a three-dimensional solid model and finite element model of nickel titanium endodontic instruments in three different cross-sectional shapes, geometric model and finite element model of the eight different curved root canals. 2, the stress distribution results of this experiment show that: the greater the bending angle, the smaller the bending radius, the greater the model of the device, the higher the stress level of nickel titanium endodontic instruments. Bend radius is to determine the most critical parameters of nickel titanium endodontic instruments stress level. 3, the experimental stress distribution: the bending stress of the U-shaped triangular ProFile minimum convex equilateral triangle ProTaper minimum torsional stress. Bending under simulated conditions, the stress concentration at the groove of the ProFile, ProTaper and ProTaper Universal cutting edge; simulation conditions under torsion stress concentration on the convex side of the ProTaper with ProFile or ProTaper Universal groove. Conclusion 1, the experimental results show that the three-dimensional finite element analysis can be successful simulation study of the mechanical properties of the nickel titanium endodontic instruments under different boundary conditions and load status. 2, curved root canal parameters significantly affect the stress distribution of nickel titanium endodontic instruments in curved root canals. Observation of the most dangerous conditions of use, we believe that in order to prevent damage and broken nickel titanium endodontic instruments, queen-size nickel-titanium endodontic instruments should be discarded after use of sharp bends root canal. 3, the cross-sectional shape of the nickel-titanium endodontic instruments significantly affect the bending and torsion properties: preparation ① ProTaper and ProTaper Universal fit narrow small root canals; while the ProFile more suitable for the preparation of curved root canals, prepare narrow root canals need to be cautious. (2) U-shaped groove improved design to improve the the ProTaper Universal flexural performance made a slight decrease in anti-torsion properties.

A Computational Analysis of Bending and Torsional Properties of Three Nickel-Titanium Endodontic Instruments with Different Cross-sections

Abstract

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