Tungsten-based esthetic orthodontic archwire model
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Citation
Abstract
The development of a unique orthodontic wire with a more esthetic appearance was the aim of this research. Tungsten’s properties as a wire are unique in some ways and were explored as a base material for an esthetic wire. The stiffness of Tungsten, due to its high modulus of elasticity value – double that of stainless steel - was to be used for development of a clinically useful prototype. Several methods focusing on the production of such a wire are detailed including some methods that were less successful. The development of such a prototype wire was ultimately most successful using a thin layer of powder coating to wires of several different thicknesses. TGIC, a polyester powder spray, was applied and the resulting wires were tested, along with specimens produced by a different method. The wires produced in this different method consisted of several specimens containing thin tungsten filaments (.005” dia.) surrounded by a white epoxy material (3M DP-100FR). The number of filaments varied from 7, to 12, to 16. When viewed under microscopic cross-section the 7-filament wires showed the most consistent morphology of 1 central filament and 6 outer filaments.
Results: The results of cantilever bending tests were used to obtain modulus of elasticity values. Testing on a Universal Instron Machine showed consistent results for the powder coated models. The range of their values was between 221 - 228 GPa. The other group of wires showed an increase in modulus value for each increase in filament number, from 7 to 12 to 16 filaments; the values were 112 GPa, 162 GPa and 385 GPa, respectively.
Conclusion: The powder coated specimens showed the best esthetic results and can be used as a model for further study. The modulus values of these specimens are within an acceptable clinical range, albeit stiffer than stainless steel wires. Questions remain regarding the biocompatibility, staining, frictional forces within brackets, resistance to chipping or cracking of the powder coating, and suitability of other type of powders for coating. Furthermore, the ability to coat rectangular cross-section wires would greatly enhance the clinical usefulness of any new type of wire. The wires used in this experiment were circular in cross-section.
Description
Thesis (MSD)--Boston Univeristy, Goldman School of Dental Medicine, 2007 (Dept. of Orthodontics and Dentofacial Orthopedics).
Includes bibliographical references: leaves 41-42.
Includes bibliographical references: leaves 41-42.
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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.