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

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The design of this study does not entirely represent what might occur in clinical situations. Because teeth tend to tip and rotate during tooth movement, 6 the effects of first- and second-order angulations on slot-wire friction should not be ignored when selecting a set of crown-attachments. The research design and execution did, however, help to highlight and evaluate factors associated with friction in attachment-designs. Observations from this study lead to the recommendation that measures should be taken to reduce the amount of torque in the buccal segments before beginning en masse retraction of the anterior teeth. Future studies evaluating the collective contributions of tip, rotation and torque in a multiple crown-attachment setup could be helpful in determining optimal treatment-mechanics in certain clinical situations. Conclusions The results of this study confirmed that the presence of third-order torque can contribute to kinetic frictional resistance in the buccal segments during anterior retraction using sliding mechanics with crown-attachment sets including self-ligating brackets. At small torque angles, friction will tend to be less with passive than 70
with active, self-ligating sets. The findings suggest that a noticeable effect from friction will be seen when the torque reaches and exceeds the third-order clearance-angle of the wire-slot combinations. Furthermore, variations in bracket-ligation design can influence the amount of friction produced, particularly at torque-values beyond the clearance-angle. When there is no torque present in the second premolar slot, attachment-sets with either passive or active self-ligating brackets will generate less friction than sets that include elastomerically ligated brackets. As torque increases toward the clearance-angle, however, differences in frictional resistances across crown-attachment sets generally lessen. Beyond this torque value, the differences in frictional resistance may not depend upon the category of ligation, but, instead, upon the basic design of the ligation mechanism. 71
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THE EFFECTS OF THIRD-ORDER TORQUE A
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of torque, all five attachment sets
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COMMITTEE IN CHARGE OF CANDIDACY: A
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ACKNOWLEDGEMENTS The author wishes
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LIST OF TABLES Table 2-1: Partial O
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CHAPTER 1: INTRODUCTION The special
Page 13 and 14:
CHAPTER 2: REVIEW OF THE LITERATURE
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surfaces. 6 The magnitudes of the c
Page 17 and 18:
Since the introduction to orthodont
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that the application of the Amonton
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archwires. At binding angulations,
Page 23 and 24:
A phenomenon known as “cold weldi
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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: set, when the torque angle was incr
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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