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

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ackets. Peterson’s group 31 also found that bracket width had no effect on friction. Frank and Nikolai, 5 however, found that frictional force increased as bracket width increased. This outcome was allegedly due to decreased interbracket distance and to the wider bracket binding at a smaller angulation. Other researchers found a similar effect, but thought the cause was the mesiodistal slot dimension of the wider bracket resulting in greater stretching of the ligature, which in turn, lead to increased normal forces of ligation. 23 A third group of studies found that narrower brackets produced more friction than wider brackets. 21,22,81 Drescher’s group 22 believed that the increased tipping seen in narrow brackets resulted in greater frictional forces. Using biomechanical analysis and mathematical formulations, Schlegal 86 determined that neighboring brackets had an extraordinary influence on friction within a bracket, and, due to this influence, single-bracket studies could not accurately determine how bracket width affected friction. He concluded that interbracket distance, wire stiffness and relative bracket position must also be considered when determining the ideal slot width. Bracket width may have an indirect influence on friction due to its relationship with interbracket distance 18
and wire stiffness. As bracket width increases, the distance(s) to the adjacent bracket(s) will decrease, resulting in shorter and stiffer sections of wire. 5,7 The influence of bracket width is more pronounced at greater angulations. Slot size has not been found to influence frictional resistance in the fixed appliance. 21,27 Kusy, Whitley and Prewitt 27 evaluated several factors, and they concluded that there was no substantial difference overall in frictional resistance between a 0.018-inch and a 0.022-inch bracket- slot when each is paired with a comparable-sized archwire. Ligation Ligation has become a popular topic among researchers in the field of orthodontics. Orthodontic products have been developed toward reducing friction potential in the fixed appliance and some seemingly have suppressed a major contributor by augmenting traditional methods of ligation within modern bracket designs. Current, common categories of ligation are 1) small, ductile, stainless steel wire- segments, 2) elastomeric o-rings and ties and 3) self- ligation. 19
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: acket and the gold-lined Luxi brack
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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