Multistranded Wires Research Articles

Mechanical properties and clinical applications of orthodontic wires

This review article describes the mechanical properties and clinical applications of stainless steel, cobalt-chromium, nickel-titanium, beta-titanium, and multistranded wires. The consolidation of this literature will provide the clinician with the basic working knowledge on orthodontic wire characteristics and usage. Mechanical properties of these wires are generally assessed by tensile, bending, and torsional tests. Although wire characteristics determined by these tests do not necessarily reflect the behavior of the wires under clinical conditions, they provide a basis for comparison of these wires. The characteristics desirable in an orthodontic wire are a large springback, low stiffness, good formability, high stored energy, biocompatibility and environmental stability, low surface friction, and the capability to be welded or soldered to auxiliaries. Stainless steel wires have remained popular since their introduction to orthodontics because of their formability, biocompatibility and environmental stability, stiffness, resilience, and low cost. Cobalt-chromium (CoCr) wires can be manipulated in a softened state and then subjected to heat treatment. Heat treatment of CoCr wires results in a wire with properties similar to those of stainless steel. Nitinoi wires have a good springback and low stiffness. This alloy, however, has poor formability and joinability. Beta-titanium wires provide a combination of adequate springback, average stiffness, good formability, and can be welded to auxiliaries. Multistranded wires have a high springback and low stiffness when compared with solid stainless steel wires. Optimal use of these orthodontic wires can be made by carefully selecting the appropriate wire type and size to meet the demands of a particular clinical situation.

Comparative range of orthodontic wires

ADA specification No. 32 for determining the range (elastic limit) of orthodontic wires uses the bending of a wire section treated as a cantilever beam. An alternative method for defining the range of orthodontic wires proposed by Waters (1981) is to wrap wire sections around mandrels of varying, diameters and measure the deformation imparted after unwrapping. Four brass mandrels with a total of 46 test diameters ranging from 3.5 to 60.0 mm were used in this study. Wire sections 9 cm in length were rolled on the mandrel with a hand lathe. The mandrel cross section required to produce a predetermined amount of deformation (2 mm arc height for a 5 cm chord) was defined as the yield diameter for that particular wire. No individual wire was tested twice so as to avoid introduction of strain history. Test samples of 488 different orthodontic wires supplied by nine commercial distributors were evaluated (a total of 4,747 samples). Stainless steel wires of identical dimensions had a large variation in range, depending on the state of strain hardening and heat treatment. For example, 0.020 inch round wire had yield diameters ranging from 22.8 mm for Australian special plus orange (TP Laboratories) to 42.9 mm for Nubryte gold (G.A,C. International). Chromium cobalt wires had less range than stainless steel before heat treatment, but increased greatly in range after heat treatment. Nitinol (Unitek) had the greatest range of all wires tested (yield diameter of 8.7 mm for 0.016 inch Nitinol). Multistranded stainless steel wires had yield diameters between 9.0 and 14.0 mm.

The Identification of Cut Multistranded Wires

Abstract The theft of electrical equipment often involves the cutting of attached wires to expedite removal of the equipment. This situation presents the investigator with the problem of determining that wire segments attached to stolen articles were at one time joined to wire segments at the site of the theft. The usual approach taken by the forensic scientist is to effect an identification by demonstrating a physical match between the cut ends of the wire segments. Other methods utilized to compare cut wire segments include quantitative comparison of trace elements by neutron activation analysis [1,2] and by emission spectrography [3].

Design of a Digital Telemetry Unit using Dot Components

It has long been apparent that uniformity of the body geometry and of the lead geometry and material of electronic parts is highly desirable. Dot or pellet component parts provide such uniformity to a high degree and thus lend themselves to the design of equipment of considerable sophistication. To demonstrate the technique a digital telemetry unit, previously packaged in the form of welded cordwood modules, was designed using dot components. The unit consists of some 1200 parts disposed on six card-shaped modules measuring 3 x 6.7 x 0.03. Modules are made of molded epoxy and are color coded for assembly and trouble shooting purposes. Silkscreened conductive adhesive is used for intraconnections. All interconnections (i.e. external to modules) are brought out along one edge of the module in the form of flexible, multistranded wires. These wires are permanently soldered, book fashion, to an interconnection matrix consisting of an array of welded tubes. By treating the modules as pages in a book, all parts are accessible for inspection or replacement without disconnecting any section of the circuit. Foil-clad balsa wood spacers are provided for separation between adjacent modules. The modules and spacers are stacked and compressed by means of two rigid end plates and two screws, thus providing a compact, prestressed structure virtually immune to shock and vibration.