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

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friction with active torque present in the wire and/or slot was also evaluated. Materials and Methods The posterior maxillary right quadrant with a first premolar extracted and canine retracted was simulated to evaluate the friction produced in a buccal segment during retraction of the half-incisal segment; third-order torque was generally activated at the second premolar position. A 0.019- by 0.025-inch stainless steel wire was selected for this study because it is frequently selected as the retraction archwire. The two independent variables controlled in this study were the bracket ligation design and the third-order torque angle at the second premolar bracket. The dependent variable was the kinetic friction generated in the appliance when a wire was slowly pulled posteriorly through the crown-attachments. The friction testing device is described in the Master’s thesis by Bunkall. 58 The device consists of a series of aluminum cylinders (“teeth”) mounted into a base- plate in an archform representing a maxillary quadrant. Through each cylinder is an adjustable stainless steel rod with an attached brass faceplate that simulates the facial 56
surface of a tooth-crown. The construction of the cylinder subassembly allows the faceplate to be positioned in all three dimensions of space. The mechanism was fabricated to enable the control of multiple bracket-slot locations and orientations. In the present study, four aluminum cylinders, representing the maxillary right canine, second premolar, first molar and second molar, were inserted into the four posterior mounting holes in the aluminum base- plate (Figure 3-1). The stainless steel rod and knuckle- joint set-screw were rotated 90 degrees on each “tooth” to aid in the third-order positioning of the 0.022-inch brackets and tubes. Crown-attachments were bonded to the brass faceplates. Seven bracket-positioning templates were fabricated from 0.022-inch-thick steel plates. Each template was prepared to enable control of the positions of the slots of the four crown-attachments; the slots were temporarily “engaged” and “filled” by the working edge of the template. At the site of the second-premolar bracket-slot, a rectangular section of the steel plate was cut away, 0.025 inches from the working edge of the template. The cutout left a 0.022- by 0.025-inch cross-section within each of the six templates; the small “bar” was inelastically rotated along its central longitudinal axis to one of six 57
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 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: unconstrained rotation around the l
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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