The effects of third-order torque and self - Saint Louis University

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interface of wire and crown-attachment slot. These parameters are alloy composition, surface-roughness, and cross-sectional shape and size. Alloy Composition At angulations in which second-order binding existed of the wire within the bracket-slot, Frank and Nikolai 5 found that nickel-titanium alloy wires produced smaller maximum static frictional forces than did a stainless steel wire of the small size, likely due to the smaller modulus of elasticity of the former alloy. One of the many important findings from this study was that, due to variances in modulus of elasticity and surface roughness across as-received wires, archwire-alloy influenced frictional resistance. Since then, dozens of studies have compared frictional force values generated across wires differing by alloy. Some experimental studies have suggested that, typically within stainless steel slots, stainless steel wires tend to produce less sliding friction than nickel-titanium alloy wires. 17-30 When testing with second-order angulations that produce binding within the bracket-slot, however, other studies have reported less friction with the nickel-titanium alloy wires. 4,5,31-34 This behavior is related to the modulus of elasticity for the 10
archwires. At binding angulations, two contacts form at the ends of the bracket-slot, one on the occlusal face of the wire and one on the gingival face. As the wire deflects upon activation, those wires with a greater modulus of elasticity will produce larger normal bracket- wire contact forces at those contact points. 5,48 Several investigations have found that ß-titanium alloy wires have greater resistance to sliding than either stainless steel or nickel-titanium alloy wires, particularly in the absence of binding. 18,20-24,26,27,29,35,36 Tspelepsis and associates 33 failed to detect any such differences across the three alloys. Surface Characteristics Frank and Nikolai 5 found that, with small, nonbinding angulations and in stainless steel slots, stainless steel wires exhibited less sliding frictional resistance than nickel-titanium alloy wires. This difference was thought to be related to the roughness of the wire-alloy surface. This property of a wire is determined by characteristics of the alloy, the manufacturing process, any surface treatment and, for some materials, the shelf-time and/or use-time. 5 Other researchers have speculated that the greater friction produced by titanium alloy wires when compared to stainless 11
Page 1 and 2: THE EFFECTS OF THIRD-ORDER TORQUE A
Page 3 and 4: of torque, all five attachment sets
Page 5 and 6: COMMITTEE IN CHARGE OF CANDIDACY: A
Page 7 and 8: ACKNOWLEDGEMENTS The author wishes
Page 9 and 10: LIST OF TABLES Table 2-1: Partial O
Page 11 and 12: CHAPTER 1: INTRODUCTION The special
Page 13 and 14: CHAPTER 2: REVIEW OF THE LITERATURE
Page 15 and 16: surfaces. 6 The magnitudes of the c
Page 17 and 18: Since the introduction to orthodont
Page 19: that the application of the Amonton
Page 23 and 24: A phenomenon known as “cold weldi
Page 25 and 26: of round wire with the slot created
Page 27 and 28: acket and the gold-lined Luxi brack
Page 29 and 30: and wire stiffness. As bracket widt
Page 31 and 32: ligation-friction relationship. The
Page 33 and 34: designs have been introduced to the
Page 35 and 36: otated tooth or a twisted rectangul
Page 37 and 38: to incisor irregularity after initi
Page 39 and 40: added. Similarly, Bunkall 15 noted
Page 41 and 42: couple, resulting in the delivery i
Page 43 and 44: Another factor that influences brac
Page 45 and 46: References 1. Stoner MM. Force cont
Page 47 and 48: 19. Kusy RP, Whitley JQ, Ambrose WW
Page 49 and 50: 37. Kusy RP, Whitley JQ, Mayhew MJ,
Page 51 and 52: 56. Khambay B, Millett D, McHugh S.
Page 53 and 54: 75. Tecco S, Festa F, Caputi S, Tra
Page 55 and 56: 93. Thorstenson GA, Kusy RP. Effect
Page 57 and 58: Tables Table 2-1: Partial Overview
Page 59 and 60: significantly less friction than th
Page 61 and 62: optimal clinical results. Fixed-app
Page 63 and 64: self-ligating bracket systems to ma
Page 65 and 66: unconstrained rotation around the l
Page 67 and 68: surface of a tooth-crown. The const
Page 69 and 70: 0.025-inch NuBryte Standard Arch st
Page 71 and 72:
test-archwire in place and ligated,
Page 73 and 74:
aseline values at 0 degrees of torq
Page 75 and 76:
increased to only five degrees. The
Page 77 and 78:
tension on one edge of the wire and
Page 79 and 80:
set, when the torque angle was incr
Page 81 and 82:
with active, self-ligating sets. Th
Page 83 and 84:
11. Kusy RP, Whitley JQ. Effects of
Page 85 and 86:
33. Andreasen GF, Quevedo FR. Evalu
Page 87 and 88:
54. Downing A, McCabe JF, Gordon PH
Page 89 and 90:
76. Thorstenson GA, Kusy RP. Effect
Page 91 and 92:
Table 3-2: Significance levels (α
Page 93 and 94:
Table 3-4: Mean differences in fric
Page 95 and 96:
Figure 3-3: Control of the third-or
Page 97 and 98:
Figure 3-9: Victory bracket Figure
Page 99 and 100:
Figure 3-12: Cross-section diagrams
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