Browsing by Subject "Orthodontic Wires"
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Item A Comparative Study of the Fatigue Resistance of Four Orthodontic Alloys(1983) Kamisugi, Curtis N.This investigation was designed to compare the fatigue resistance of four orthodontic alloys and to determine whether their surface characteristics had any influence on their fatigue lives. Stainless steel, Blue Elgiloy, TMA, and Nitinol were evaluated using a round (.018") and a rectangular (.016" x .022") size of each type of alloy. Fifty specimens of each size were tested, making the total sample size 400. The wire samples were evaluated using a cantilever bend test in which each specimen was stressed cyclically at the defection of .625 inch in either direction. All of the wires were evaluated in their untreated condition, with the exception of Blue Elgiloy, which was heat-treated prior to testing at 900° Fahrenheit for seven minutes in a burnout furnace. One specimen from each group was viewed under the scanning electron microscope to evaluate its surface structure and each alloy presented a unique microstructure. Stainless steel was relatively smooth. Blue Elgiloy was slightly rougher in appearance, Nitinol appeared dimply and crater-like, and TMA looked eroded or striated. It was suspected that the alloys which had a rough surface would be less resistant to fatigue. On the other hand, due to the differences in modulus of elasticity of each alloy, the amount of stress applied to the different materials varied accordingly and the effect of surface roughness on fatigue resistance was not great enough to overcome the effect of stress. Since TMA and Nitinol had relatively low moduli of elasticity, they were subjected to less stress and were thus more fatigue-resistant than either stainless steel or Blue Elgiloy. Nitinol sustained the most cycles to fracture in both the round and rectangular samples. In the round sample, TMA had the next best fatigue life, and stainless steel and Blue Elgiloy had comparable fatigue lives. With the rectangular samples, there were no significant differences between TMA, stainless steel, and Blue Elgiloy. Therefore, although Nitinol and TMA cost more than stainless steel or Elgiloy, their high flexibility, large working ranges, and favorable fatigue properties make them attractive substitutes for the conventional stainless steel or Elgiloy wires. TMA and Nitinol provide a new dimension in controlling the magnitude of forces used for tooth movement, and Burstone40 has stated that "the variable-modulus concept gives the orthodontist one more tool in the efficient design and use of his appliance."Item A Torsional Analysis of Stainless Steel Orthodontic Wires(1962) Mulligan, Thomas F.Maximal torque and torque-twist rate were determined for straight lengths of wire. The effect of wire length on each was studied. Anti-rotational torque was determined for cuspid retraction springs, and finally, distal root torque produced by cuspid retraction springs and anterior retraction springs was determined. Torque watch gauges in combination with a Bunsen burner assembly and self-devised deflection scale were used to determine the data. Maximal torque was shown to be independent of wire length, and closely approximated the theoretically determined values, while twist was shown to be proportional to wire length. Pre-stressing followed by stress-relief produced the highest maximal torque values, while wires which received neither type of treatment exhibited the lowest values. Torque-twist rate was determined for a number of wires commonly used in orthodontics, both experimentally and theoretically. It was shown that anti-rotational torque produced by cuspid retraction springs used in the Segmented Arch Technique was not only capable of preventing cuspid rotation during distal tooth movement, but could actually move the distal of the cuspid labially on the basis of theoretical mechanics. Initial activation of anterior retraction springs used in the Segmented Arch Technique produces added distal root torque for the appliance when activated for distal tooth movement, while it appears that both cuspid and anterior retraction springs produce sufficient distal root torque to prevent forward root displacement.Item An Analysis of the Fatigue Resistance of Beta Titanium and the Effect of Spot-Welding Upon the Fatigue Resistance of this Alloy(1984) Wong, Michael B.; Garner, LaForrest; Baldwin, James; Moore, Keith; Barton, Paul; Shanks, JamesThis investigation was designed to establish a fatigue curve for beta titanium, determine the effect of spot-welding upon the fatigue resistance of this alloy, and provide qualitative observations about surface characteristics of different batches of TMA in relation to their fatigue lives. Rectangular .016" x .022" 1MA was evaluated. Twelve specimens in each group were tested, making the total sample size 108. The wire samples were evaluated using a cantilever bend test in which specimens were stressed cyclically at varying deflections. Two welded groups were also tested. An auxiliary .016" x .022" TMA was welded to a main test segment of TMA with the .016" side against the opposing .016" side. The weld overlap varied at 25% for one group and 50% for the other. These specimens were stressed at the area adjacent to the weld. One specimen from each group was viewed under the scanning electron microscope to evaluate the fractured area. Specimens from three different batches of 1MA were tested and their fatigue lives compared at .625 inch deflection. One specimen from each batch was viewed under the scanning electron microscope to evaluate its surface structure. A fatigue curve for TMA was plotted from the data. At .625 inch deflection, welding an auxiliary onto the main segment significantly decreased the fatigue resistance of the wire. However, both welded groups had comparable fatigue lives. These wire specimens fractured at some point adjacent to the welded site. Fatigue resistance differed significantly between one batch of TMA and the other two. The scanning electron micrographs of representative specimens from each batch seemed to indicate that the fatigue resistance of each batch was inversely related to its surface roughness.Item An analytical approach to 3D orthodontic load systems(The Angle Orthodontist, 2014-09) Katona, Thomas R.; Isikbay, Serkis C.; Chen, Jie; Department of Orthodontics and Oral Facial Genetics, IU School of DentistryOBJECTIVE: To present and demonstrate a pseudo three-dimensional (3D) analytical approach for the characterization of orthodontic load (force and moment) systems. MATERIALS AND METHODS: Previously measured 3D load systems were evaluated and compared using the traditional two-dimensional (2D) plane approach and the newly proposed vector method. RESULTS: Although both methods demonstrated that the loop designs were not ideal for translatory space closure, they did so for entirely different and conflicting reasons. CONCLUSIONS: The traditional 2D approach to the analysis of 3D load systems is flawed, but the established 2D orthodontic concepts can be substantially preserved and adapted to 3D with the use of a modified coordinate system that is aligned with the desired tooth translation.Item Comparison of Frictional Forces Between Three Grades of Low Friction "Colors" TMA(2001) Rosenthall, Mark R.; Oshida, Yoshiki; Baldwin, James; Hohlt, William; Katona, Thomas; Shanks, JamesFrictional forces between archwires and brackets play a significant role in the efficiency of orthodontic tooth movement. The purpose of this investigation were to (1) compare the wet static frictional forces of low friction "Colors" TMA ™ arch wires with arch wires of other materials (stainless steel, NiTi, and uncoated TMA ™) and (2) test the effects of repetitive sliding. Testing was accomplished by using a cantilever testing device, which held the archwire in place between two 303 stainless steel test flats. The test flats were used to simulate an orthodontic bracket. A saliva substitute (Ringer's solution) was used to simulate the oral environment. Six wire types (stainless steel, NiTi, TMA ™, and three types of "Colors" TMA ™ wires [purple, aqua and honeydew]). For each said wire type, 15 archwires were tested. Each archwire type was run five times at three different weights (normal forces) and each wire was subjected to five repetitions. In total, 450 runs were established. The effects of wire type (6 types), normal force (1267g, 2153g, 2533g) and repetition (5 per wire) on wet static frictional were examined using three-way analysis of variance (ANOVA). Pairwise comparisons between treatment combinations were made using Sidak method to control the overall significance level. After wire testing, a sample of untested (0 runs) and tested (1 run, 5 runs) wires were viewed under a light microscope at 160X magnification. The results indicated uncoated TMA ™ wires produced the highest wet static frictional forces. In general, NiTi produced the next highest force levels followed by the three "Colors" TMA ™ wires, and then stainless steel. Repetition was observed to affect only NiTi and uncoated TMA TM wires. NiTi wires showed a decrease in force values between runs 1 and 5 at p < 0.05. Uncoated TMA ™ showed an increase in force values between runs 1 and 2. The cause for these findings could not be validated by light microscope evaluation.Item A Comparison of Frictional Forces During Simulated Cuspid Retraction on a Continuous Edgewise Archwire(1982) Allai, W. Wesley; Garner, LaForrest D.; Sondhi, Anoop; Shanks, James C.; Swartz, Marjorie L.; Barton, PaulThis investigation was designed to compare the force (grams) required to overcome a simulated cuspid retraction assembly capable of three dimensional control during the retraction process. It was hypothesized that a significant difference in the mean retraction values exists between the newer orthodontic alloys of Nitinol, Beta-Titanium, as well as Stainless Steel. One hundred eighty bracket and archwire combinations were examined as follows: Sample # Wire Cross-section Wire Material 30 .016”x.022” Stainless Steel 30 .017”x.025” ” 30 .016”x.022” Nitinol 30 .017”x.025” ” 30 .016”x.022 Beta-Titanium (TMA) 30 .017”x.025” ” A statistically significant difference was shown to exist between all six groups examined regarding the variables of wire size and wire material. The statistical analysis revealed that increasing rectangular archwire cross-sectional size from .016"x.022" to .017"x.025” rectangular wire when simulating canine retraction using an .018" slotted Lewis bracket will lead to significantly greater functional forces. The analysis of wire materials indicated that a significant difference (p=.01) exists between rectangular Beta-Titanium (TMA), Nitinol, and stainless steel during simulated cuspid retraction utilizing a narrow .018" Lewis bracket ligated with A-lastik ligatures. The least frictional force was observed with the .016"x.022" stainless steel test cells. The largest frictional force was found in the .017”'x.025" Beta-Titanium retraction specimens. Nitinol revealed force data intermediate between stainless steel and Beta-Titanium. The maximum resistance assembly developed 2.3 times the minimum frictional force observed. The mean grams of frictional force within these test cells ranged from 55.03 grams for the .016"x.022" retraction assembly to 132.68 grams for the .017"x.025" Beta-Titanium assembly. A topographical scanning electron microscope survey of the brackets and archwires utilized was included to provide qualitative insights into the quantitative results described.Item The Effect of Wire Fixation Methods on the Measured Force Systems of a T-Loop Orthodontic Spring(1997) Gregg, Joseph R.; Chen, Jie; Baldwin, James J.; Katona, Thomas R.; Shanks, James C.Ideal orthodontic springs are able to provide a controlled moment-to-force (M/F) ratio and a low load deflection rate. A great deal of research has gone into describing force systems generated by orthodontic springs. Most studies investigating the force system generated by T-loops have used rigid fixation for the spring ends. This is practical for laboratory studies, but it does not truly represent clinical situations in which orthodontic brackets are used to anchor spring ends. Results from laboratory studies have been applied to clinical situations without regard to what effect, if any, the method of end fixation may have. It is the goal of this study to determine the effects of spring fixation on generated force systems. The springs were held by rigid fixation and bracket ligation with either elastomeric or steel ligature ties. Comparison of these fixation methods was made by testing T-loops of different dimensions, with and without heat treatment at various activation distances. In theory, the wire is ligated rigidly against the bracket, so that the combination acts as a single unit by rigid fixation. Thus, there should be no difference between the generated force systems when spring ends are held by rigid fixation, or when they are held in place with orthodontic brackets and ligated by either elastomeric or steel ligature ties. However, the results indicate that are significant differences among the methods of fixation for each spring variation and heat treatment. The rigid fixation method consistently produced smaller moments and M/F ratios for all springs with every activation and heat treatment combination.Item Heat Treatment of Orthodontic Steel Wire(1958-06) Denver, Paul IrwinA study was made to ascertain the effect of heat treatment, at a time-temperature ratio of three minutes at 900 F., on orthodontic 18-8 and Elgiloy steel wire with respect to the followings a) the ability of a vertical loop to resist permanent deformation when subjected to a tensile load; b) the effect of heat treatment on ductility of a steel orthodontic wire; c) the effect of heat treatment on the warpage of a orthodontic wire which has previously been formed. A standardized nine millimeter vertical loop was incorporated in the wire. Weights in increments of 100 grams were suspended from one end of the wire while the other end was firmly held in a vice. Permanent deformation as a result of a given load was determined by the amount of permanent opening of the vertical loop. The force just necessary to produce a permanent opening of the vertical loop is defined as the proportional limit. The ability of Elgiloy to resist permanent deformation due to heat treatment is enhanced as much as 66 percent. On the other hand, Elgiloy heat treatment produces the undesirable side effect of reducing ductility i.e., as high as 77 percent reduction in ductility following heat treatment. Therefore a Elgiloy steel wire cannot be altered in shape to any great extent after heat treatment. Eighteen-eight type 304 steel wire, when subjected to the same treatment, shows an increased ability to resist permanent deformation i.e. a 39 percent increase in proportional limit following heat treatment. It is significant that ductility, as determined by the cold bend test, is not significantly affected by heat treating 18-8 steel wire. The latter phenomena supports the claim of many investigators that 18-8 steel is not capable of a true heat treating transformation and therefore any improvements in elastic properties as a result of heat treatment can be considered to be due to a stress-relieving process. Ductility, as determined by the cold bend test, was found to be a highly variable property. Large variations in ductility were even found in the same feet-length of wire. Both 18-8 and Elgiloy steel wire exhibit this phenomena. Following heat treatment of Elgiloy a reduction in the variability of ductility was noted in all the wires tested. The effect of heat treatment on warpage of a previously shaped orthodontic steel wire was studied by incorporating a right angle bend in the center of a four inch section of wire. After a three week storage at a constant temperature of 98.6m to simulate mouth conditions, the angles were again measured. Any alteration in degrees from the right angle was considered to be indicative of warpage. Heat treated wires were compared to non-heat treated. Heat treatment appears to increase warpage in orthodontic steel wires; however, because of large variations no conclusive results were obtained with respect to this problem.Item Load-Deflection Determinations of Specific Wire Configurations(1960-07) Fryar, Gene M.A method was devised for the measurement and tabulation of load-deflection values for various wire spring configurations that are commonly used for orthodontic procedures. 1. The deflection of a simple cantilever varies as the third power of the length. 2. The incorporation of a helix into a cantilever at the area of maximum stress markedly increased the deflection. 3. The addition of a helix into a short lever produced a proportionately greater amount of deflection than did the addition of a helix into a long lever. 4. Under continued loading, the rate increased on all springs tested. 5. The load-deflection characteristic of a base arch is approximately the same as that of a simple cantilever. 6. Alteration of the spring height greatly affects the load-deflection values of the retraction springs. Reducing the spring height from 10 mm. to 8 mm., resulted in an increase of approximately 1.5 times as much force being delivered.Item Load-Deflection Rates and Maximum Deflection of Orthodontic Appliances(1958) Lawless, David T.For purposes of clarity and organization, the subject matter was divided into four separate phases. Each phase is distinct in that it deals with a specific facet of orthodontic force application; however, all phases are similar in that they deal with a measurement of force values. The first phase of the thesis deals with a measurement of load-deflection rates of various arch wire designs. These arch wire designs were in the form of vertical loops or helical torsion springs, i.e., a vertical loop in combination with one or more 360⁰ loops contained therein. The load-deflection rate in grams of force per mm. of deflection along with the maximum deflection of each wire design is given in table form in the study. Stainless steel wires marketed by the Rocky Mountain and Unitek Companies were tested in the study along with a new type of alloy known as Elgiloy. In the second phase of the thesis, load-deflection rates of 360⁰ loops were determined. Both single and double 360⁰ loops were determined. Both single and double 360⁰ loops were tested. The force was applied to the loops in three ways, i.e., to close the loops, to open the loops, and at right angles to loops. These various load-deflection rates were presented in graph form in the thesis. In the third phase of the thesis, load-deflection rates of some commonly used orthodontic elastics were determined and represented in graph form. A considerable lack of uniformity in regard to wall thickness and diameter was found in a great number of these elastics. In the fourth phase of the thesis, a method has been described to obtain effective torque in the anterior segment using round wire. It was found that as much as 360 grams of force can be obtained in this way with .016” wire and as much as 660 grams with .020” wire.