Physical, mechanical, and flexural properties of 3 orthodontic wires: an in-vitro study.
BACKGROUND
Understanding the biologic requirements of orthodontic patients requires proper characterization studies of new archwire alloys. The aims of this study were to evaluate properties of wires made of 2 new materials and to compare their properties with those of stainless steel.


METHODS
The sample consisted of 30 straight lengths of 3 types of wires: stainless steel, titanium-molybdenum alloy, and beta-titanium alloy. Eight properties were evaluated: wire dimension, edge bevel, composition, surface characteristics, frictional characteristics, ultimate tensile strength (UTS), modulus of elasticity (E), yield strength (YS), and load deflection characteristics. A toolmaker's microscope was used to measure the edge bevel, and x-ray fluorescence was used for composition analysis. Surface profilometry and scanning electron microscopy were used for surface evaluation. A universal testing machine was used to evaluate frictional characteristics, tensile strength, and 3-point bending.


RESULTS
Stainless steel was the smoothest wire; it had the lowest friction and spring-back values and high values for stiffness, E, YS, and UTS. The titanium-molybdenum alloy was the roughest wire; it had high friction and intermediate spring-back, stiffness, and UTS values. The beta-titanium alloy was intermediate for smoothness, friction, and UTS but had the highest spring-back.


CONCLUSIONS
The beta-titanium alloy with increased UTS and YS had a low E value, suggesting that it would have greater resistance to fracture, thereby overcoming a major disadvantage of titanium-molybdenum alloy wires. The beta-titanium alloy wire would also deliver gentler forces.
Department of Orthodontics & Dentofacial Orthopedics, Panineeya Mahavidhyalaya Institute of Dental Sciences & Research Centre, Kamala Nagar, Dilsukh Nagar, Hyderabad, India.
Shubhaker Rao
SR
Juvvadi
Vignesh
V
Kailasam
Sridevi
S
Padmanabhan
Arun B
AB
Chitharanjan
D000497:Alloys / Q000032:analysis / Q000737:chemistry; D055598:Chemical Phenomena; D002857:Chromium / Q000032:analysis; D003722:Dental Alloys / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D055119:Elastic Modulus; D004548:Elasticity; D017276:Friction; D006801:Humans; D007501:Iron / Q000032:analysis; D008422:Materials Testing; D055595:Mechanical Phenomena; D008855:Microscopy, Electron, Scanning; D008982:Molybdenum / Q000032:analysis; D009532:Nickel / Q000032:analysis; D009969:Orthodontic Wires; D018583:Pliability; D013052:Spectrometry, X-Ray Emission; D013193:Stainless Steel / Q000032:analysis / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D014001:Tin / Q000032:analysis; D014025:Titanium / Q000032:analysis / Q000737:chemistry; D015040:Zirconium / Q000032:analysis
D000497:Alloys; D003722:Dental Alloys; C525450:titanium molybdenum alloy; D002857:Chromium; D013193:Stainless Steel; D014001:Tin; D009532:Nickel; D008982:Molybdenum; D015040:Zirconium; D014025:Titanium; D007501:Iron