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

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with elastomeric ligatures). Friction values obtained from both passive self-ligating sets at ±5 degrees remained significantly smaller than the friction produced by the Victory set, likely due to the absence of any other than incidental contact from ligation within these self-ligating bracket-slots. With the exception of the In-Ovation R set and positive angles, increasing the torque from ± 5 to ±10 degrees brought the frictional resistances from the self- ligating attachment-sets to magnitudes similar to those from the Victory sets. This finding contrasted outcomes from a previous study 44 that found self-ligating brackets to produce smaller frictional forces than traditionally ligated brackets with torque placed. In the present research, interaction of the wire with the slot walls, as well as with the ligating mechanism, would be expected to occur when approaching ±10 degrees of torque, possibly tempering the alleged advantage of smaller frictional resistance that is commonly associated with self-ligating brackets. The marked increase in friction found in the self-ligating (but not in the Victory) sets when increasing the torque from ±5 degrees to ±10 degrees suggest that there were faciolingual force additions from substantial contacts with the ligating mechanisms. The In-Ovation R 68
set, when the torque angle was increased from +5 to +10 degrees, displayed substantially higher frictional resistance, possibly a result of increased normal forces due to its “active” self-ligation and the asymmetrical clip design. When the torque was increased beyond the third-order clearance values to ±15 degrees, the friction associated with the SmartClip and the In-Ovation R sets grew to significantly larger magnitudes than the values displayed by the other three sets. This finding may be related to properties of the individual ligating mechanisms of these brackets. Interactions of the archwires with the clips in both brackets were likely because of the faciolingual dimensions of the ligated slots. Bunkall 58 attributed larger frictional forces from SmartClip brackets with first-order wire-slot discrepancies to flexure of the nickel-titanium-alloy clips contributing to normal forces as well as the relative roughnesses of the nickel-titanium- alloy surfaces. The clip integral to the In-Ovation R bracket is made of a cobalt-chromium alloy which has been reported to have a greater frictional potential related to surface-roughness than stainless steel, 13 and it may also have contributed to the relatively greater resistance displayed in this study. 69
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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
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 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: tension on one edge of the wire and
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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