Comparison of Superelasticity of different Austenite active Nickel Titanium Orthodontic Archwires using Mechanical Tensile Testing and correlating with Electrical Resistivity of the same Archwires

Nagarajan, D (2007) Comparison of Superelasticity of different Austenite active Nickel Titanium Orthodontic Archwires using Mechanical Tensile Testing and correlating with Electrical Resistivity of the same Archwires. Masters thesis, Tamil Nadu Government Dental College and Hospital, Chennai.

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Abstract

Application of light and continuous forces for optimum physiological response and least damage to the tooth supporting structures should be the primary aim of the orthodontist. Nickel titanium alloys with the properties of excellent springback, superelasticity and wide range of action is one of the natural choice for the clinicians to achieve this goal. In recent periods, various wire manufacturers have come with a variety of wires exhibiting different properties. It is the duty of the clinician to select appropriate wires during various stages of treatment for excellent results. For achieving this an evaluation of the properties of these wires is essential. This study is focussed on evaluating the superelastic property of eight groups of austenite active nickel titanium wires. These wires were tested through mechanical tensile testing and electrical resistivity methods. The following are the rankings based on mechanical tensile testing. Ortho organisers wires ranked first and superior, followed by American Orthodontics and Ormco A wires. Unitek 3M and American braces wires were ranked after American Orthodontics & Ormco A wires as they exerted higher forces on deactivation. Morelli and GAC lowland NiTi wires were ranked last. In electrical resistivity tests Ormo A wires were found superior closely followed by American Orthodontics and Ortho Organisers wires. Unitek 3M, American Braces and GAC Lowland NiTi wires did not show much difference between each other and Lancer followed by Morelli remained last in the ranking. These rankings were given on the basis of the degree of phase transition from austenite to martensite, a crystallographic transformation contributing to superelastic behavior. Researchers believe that various factors like residual stress, heat treatment, alloy composition determine the expression of superelastic behavior apart from phase transition. It can be concluded that the performance of these wires based on rankings should be evaluated clinically by conducting further studies. In the future more studies should be focussed on the search for an ideal method for accurate evaluation of properties of orthodontic wires.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Superelasticity, Austenite active, Nickel, Titanium, Orthodontic Archwires, Mechanical Tensile Testing, Electrical Resistivity Archwires.
Subjects: DENTAL > Orthodontics and Dentofacial Orthopedics
Depositing User: Kambaraman B
Date Deposited: 24 Jan 2018 03:54
Last Modified: 24 Jan 2018 03:54
URI: http://repository-tnmgrmu.ac.in/id/eprint/5544

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