SBIR-STTR Award

An ideal orthodontic wire should exhibit bio-compatibility, creep resistance, weldability, formability and also, by suitable treatment, a variable elastic modulus or flexural stiffness. New titanium based shape memory effect alloys show promise of being close to this ideal. Based on preliminary studies of Titanium-Molybdenum Aluminum and Titanium-Vanadium-Aluminum alloys, it has been shown that an elastic modulus range from 2.5 to 9 x 106 psi, a 36% variation, can be achieved in these systems. Their assured bio-compatibility, based on the performance of titanium alloys in orthopedics, and their combination of shape memory effect and super-elastic behavior, makes a case for further research to characterize the properties of these two ternary alloys. Being Nickel free any of the adverse tissue reactions observed in people sensitive to this element would be avoided. To commercialize these alloys, further research on the relationship between the properties required for orthodontic application and alloy composition and heat treatment is needed. Processing procedures must also be developed for wire production. These alloys are expected to provide a significant advance in a wide range of orthodontic procedures, and in addition could be valuable new materials for general orthopedics.Awardee's statement of the potential commercial applications of the research:Orthodontic procedures require round and rectangular arch wires with a range of stiffness to effect tooth realignment. Nickel-titanium is the current preferred material, however, improved nickel-free alloys should gain a large market share. Shape memory alloys have also received a great deal attention as aids in orthopedics, and the alloys should expand the range of procedures possible in both skeletal as well as cardiovascular systems.National Institute of Dental Research (NIDR)

Based on Phase I results, Ti-Mo-Al alloys exhibit the best combination of superelastic springback, low modulus and ductility, and good potential as a new orthodontic alloy. In the short period of Phase I, optimization of the alloy composition and thermal mechanical processing was not possible. Phase II research will concentrate on Ti-Mo-Al based alloys, modifying the composition to meet the requirements of a superior orthodontic wire. Composition and processing optimization will employ a multi-component alloy design procedure using a partial factorial statistical experiment design to identify the relative importance of composition, heat-treatment and hot and cold working. The high temperature reactivity of titanium alloys creates problems in processing and heat treatment; practical processing procedures will be developed. Fundamental alloy metallurgy will be studied with respect to alloy microstructure and phase transformation kinetics. Particularly important in Phase II is the development of scaled-up alloy processing to validate the properties measured on laboratory specimens using ingots processed by techniques closer to commercial practice. The details of the effect of heat treatment on superelasticity and modulus will be determined for the optimized alloy, and the practical limits to their clinical control. Properties important to the orthodontist such as bend ductility, wire forming and weldability, will be determined on alloy wire produced from the larger scale ingot. Arch wires will be fabricated using accepted heat treating and polishing techniques to demonstrate the practicality of the final alloy selection and wire processing.