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

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difference in rate of tooth movement on the side with ion- implanted ß-titanium alloy wires engaged. 43 Cross-sectional Shape and Size Many studies have suggested that the cross-sectional size of an archwire and frictional-resistance potential may be directly related. 5,23,31,34,36,44,45 In 2003 Smith, Rossouw and Watson 34 found significantly greater friction with larger archwires than smaller ones, and they attributed this difference to greater flexural stiffnesses of the wires having larger cross-sections. Rectangular wires permit the orthodontist to exert third-order control during treatment. These wires are stiffer than round wires with similar cross-sectional dimensions. 46 The shape of the archwire cross-section influences its bending characteristics. Changes in shape from round to square to rectangular (e.g., while maintaining second-order slot-clearance), and the corresponding increases in stiffnesses, can cause increases in frictional resistance. Frank and Nikolai 5 found, however, that the smaller contact areas between the wire and bracket-slot with binding angulations in 0.020-inch round wires produced greater friction than the stiffer rectangular wires. They suggested that the point-contacts 14
of round wire with the slot created larger intensities of normal force than did the line-contacts of the rectangular wires. Brackets Orthodontic brackets are marketed in various designs, dimensions and materials, and a wealth of information exists in the literature regarding the effect of bracket- parameters on sliding friction. Influences discussed below include bracket material composition, slot size, and bracket width. Bracket Material Composition Clinicians have many choices when selecting the material composition of appliances. Stainless steel is the most common material of orthodontic brackets. These brackets are available to practitioners as cast or sintered. Traditionally, stainless steel brackets have been manufactured as castings; thereafter, specific surfaces are milled. Sintering is a process within which the stainless steel particles are compressed at elevated temperature into the desired shapes. When compared with previous research 23 using the same apparatus and wires, Vaughan et al. 29 found that the slots of sintered brackets 15
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 and 20: that the application of the Amonton
Page 21 and 22: archwires. At binding angulations,
Page 23: A phenomenon known as “cold weldi
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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The effects of third-order torque and self - Saint Louis University

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