Mechanical properties of various ceramic brackets and torque generation of stainless steel, TMA, and NiTi wires
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Abstract
There have been several studies comparing the fracture strengths of ceramic brackets. It was found that all the brackets tested in this study were strong enough to withstand the forces that were required during orthodontic treatment. Research has shown that ceramic brackets have a significantly higher frictional resistance compared to stainless steel brackets during sliding arch mechanics. In an attempt to reduce the frictional forces encountered during sliding mechanics, a particular polycrystalline bracket was manufactured with a stainless-steel insert in the archwire slot. There were no significant differences in frictional resistance between this new bracket and a stainless-steel bracket. However, there have been no studies evaluating and comparing the fracture strength of this new bracket. Torsional strength is hypothesized to be greater in ceramic brackets with a metal insert than those brackets without it. Whereas previous studies measured physical properties under ambient conditions, this study investigated their properties under a more clinically simulated environment. It is known that many ceramics tend to lose strength when they are subjected to constant loading for a period of time in a corrosive environment, such as water (static fatigue). The objectives of this study are 1) to determine if there is a difference between the fracture values of the various ceramic brackets and to determine whether the stainless steel inserted ceramic brackets are better than the all-ceramic brackets for withstanding orthodontic forces, 2) to determine if there is a difference between the fracture values of ceramic brackets in dry conditions compared to those in wet state, 3) to qualify and compare the reliability of the ceramic brackets using the Weibull analysis, 4) to examine if there are any differences in surface roughness and grain size of the various ceramic brackets, 5) to find out whether the ceramic brackets undergo static fatigue, and 6) to determine whether rectangular NiTi wires are able to generate enough moment for root torque compared to stainless steel wires.
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Description
Thesis (M.S.D.)--Boston University, Henry M. Goldman School of Dental Medicine, 2002 (Biomaterials and Restorative Sciences).
Includes bibliographical references (leaves 69-73).
Includes bibliographical references (leaves 69-73).
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This work is being made available in OpenBU by permission of its author, and is available for research purposes only. All rights are reserved to the author.