EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...

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consists of an acrylic base that typically fits against the lingual surfaces of the teeth with round 0.028” or 0.030”stainless steel wire that is incorporated into the base and fits over the occlusal aspect of certain teeth for retention, then continues as a “labial bow” that follows the posttreatment facial contour of the anterior teeth in an effort to maintain the orthodontic result. Patients are typically advised to wear their Hawley retainers full time or as much as possible during the first six months posttreatment, followed by indefinite nighttime only wear after this time. Vacuum-formed retainers (VFRs) are another common type of appliance used for retention. These acrylic retainers are fashioned out of clear 0.030” acrylic coping material (Paulson 1992) that is heated and then vacuum-formed onto plaster casts of the patients’ treated dentition. The resultant trays are then trimmed to provide 1 to 2 mm buccal and 3 to 4 mm lingual extensions past the gingival margin such that they fit over the occlusal surfaces of the teeth, including the most distal tooth (Rowland et al. 2007). These are commonly clear and are can be fabricated for the maxillary and mandibular arches. Instructions for use are similar to those of Hawley retainers. Orthodontists may use a positioner immediately following comprehensive orthodontic treatment in an effort to achieve three-dimensional control of posttreatment tooth position. Kessling (1945) described an elastomeric positioner to allow for minor tooth movements, space closure, and overbite correction if worn correctly by patients following orthodontic treatment. Nowadays, this rubber-based appliance is custom made to the patient’s posttreatment occlusion and centric relation, but adjusted to fine-tune the occlusion by allowing minor changes to occur as the patient functions in it. This type of control “helps the teeth settle into the most ideal functional and aesthetic relationships without losing the centric relation position of the mandible” (Wasson 1988, p 31). Following this “settling” of the teeth, the positioner can continue to serve as a traditional removable retainer if worn on a limited basis. The logic of removable retention is that it allows functional integration of teeth into their new positions and does not totally protect them from the posttreatment forces that they will be influenced by for the remainder of their service (Waldron 1942). Waldron (1942) further suggested that because such forces are natural forces, their effect is not only enduring, but functionally essential, and he suggested that a removable retainer that permits maximum functional freedom to the denture, while providing minimal retentive restraint, is the best form of appliance. The primary advantage of a removable retainer is that the patient (and orthodontist) maintains the ability to easily remove it for cleaning and 27
adjustment, if necessary. This ability to be removed also serves as the primary disadvantage as well. The ability of the removable retainer to maintain tooth position is completely dependent on patient compliance and wear. Lack of patient compliance regarding instructions for use can result in compromised posttreatment stability. Fixed Retention Edward H. Angle (1907) was one of the first to advocate the use of cemented bands in his retentive appliances. Today, the most commonly used form of fixed retention is some variant of a round archwire that is bonded to the lingual surfaces of the maxillary central incisors or the lingual surfaces of the mandibular anterior teeth, typically from canine to canine (Zachrisson 1977, 1978). Occasionally, the first and second premolar teeth are included if these teeth had been extremely malpositioned at pretreatment or to prevent mesial tipping of these teeth or the opening of spaces in extraction cases (Rosenstein and Jacobson 1971). The purpose of mandibular canine-to-canine fixed retention is “(1) to prevent incisor recrowding, (2) to hold the achieved lower incisor position in space, and (3) to keep the rotation center in the incisor area when a mandibular anterior growth rotation tendency is present” (Zachrisson and Büyükyilmaz 2005, p 622). Wires typically used are either a braided or a solid section of wire. Currently, the most commonly used solid wires are either a round 0.032 inch stainless steel or 0.030 inch gold-coated wire (Zachrisson 1997), bent and sandblasted on the ends for improved retention for bonding (Zachrisson and Büyükyilmaz 2005). These solid wires are usually bonded only to the lingual surfaces of the canines with light cured composite. This form of retention allows rigid fixation of the teeth, thus prohibiting the potential physiologic response of the teeth to extraneous forces exerted on them. The use of a braided wire for bonded retention has recently become popular. Proponents of the braided type wire claim that its flexibility allows for some physiologic tooth movement in response to the surrounding forces, while tooth position is maintained (Dahl and Zachrisson 1991; Bearn 1995). Typically, because of the added flexibility of these wires, clinicians are able to bond all anterior teeth to it, including the canines. Atack et al. (2007) analyzed two groups of 29 patients at least one year post debonding. One group had bonded lower canine to canine multistrand retainers placed following debonding, while the other group received lower Hawley-type retainers. Based on Little’s irregularity index, relapse was seen in both groups, but no statistical difference was found in 28
Page 1 and 2: EFFICACY OF TEMPORARY FIXED RETENTI
Page 3 and 4: DEDICATION This thesis is dedicated
Page 5 and 6: ABSTRACT Instability of the occlusi
Page 7 and 8: CHAPTER 5. DISCUSSION .............
Page 9 and 10: LIST OF FIGURES Figure 3-1. All cas
Page 11 and 12: Figure 4-14. Box plot of the distri
Page 13 and 14: Joondeph and Riedel (1994, p 908) d
Page 15 and 16: Strang (1952, p 794) claimed that
Page 17 and 18: malocclusion must be maintained if
Page 19 and 20: e aimed at maintaining, in most ins
Page 21 and 22: three time intervals: during treatm
Page 23 and 24: mechanical treatment does not neces
Page 25 and 26: elation, the masticatory system wil
Page 27 and 28: exerted on the denture from the buc
Page 29 and 30: In summary, the variance in tongue
Page 31 and 32: Sinclair and Little (1983, p 114) a
Page 33 and 34: Study and 43 orthodontically treate
Page 35 and 36: and Sakols 1982; Vaden et al. 1997;
Page 37: years postretention. Årtun et al.
Page 41 and 42: Duration of Retention The premise i
Page 43 and 44: The reduction in tooth structure of
Page 45 and 46: 4. The most stable position of the
Page 47 and 48: CHAPTER 3. MATERIALS AND METHODS Sa
Page 49 and 50: The present sample consisted of the
Page 51 and 52: Figure 3-2. Illustration of how mol
Page 53 and 54: Figure 3-3. Illustration showing di
Page 55 and 56: Figure 3-5. Illustration showing mi
Page 57 and 58: Figure 3-6. Illustration showing an
Page 59 and 60: Figure 3-8. Illustration showing in
Page 61 and 62: 34. LR3 cusp tip point. 35. Right d
Page 63 and 64: Figure 3-10. Illustration showing o
Page 65 and 66: Figure 3-11. Illustration of Inciso
Page 67 and 68: 3. Go, Gonion (anatomic): The most
Page 69 and 70: Figure 3-13. Depiction of the angle
Page 71 and 72: Figure 3-15. Illustration of the me
Page 73 and 74: Figure 3-17. Illustration of the me
Page 75 and 76: Figure 3-19. Illustration of the an
Page 77 and 78: Figure 3-21. Illustration of the up
Page 79 and 80: Figure 3-22. Illustration of the to
Page 81 and 82: Figure 3-24. Illustration of the po
Page 83 and 84: the “older” Tweed force system,
Page 85 and 86: The null hypothesis is: There was n
Page 87 and 88: Figure 4-1. Distribution of the 166
Page 89 and 90:
occlusal issues are tolerated by bo
Page 91 and 92:
40 35 30 FMA (degrees) 25 20 15 10
Page 93 and 94:
Figure 4-4. Plot of the average val
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larger ANB at the recall examinatio
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21 19 Total Chin (mm) 17 15 13 11 9
Page 99 and 100:
Figure 4-8. Box plot of the distrib
Page 101 and 102:
which a Class I relationship was no
Page 103 and 104:
Figure 4-11. Plot of mean Curve of
Page 105 and 106:
Figure 4-13. Box plot of the distri
Page 107 and 108:
Table A-4 addresses the question of
Page 109 and 110:
Figure 4-16. Bar chart of the avera
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only sample changed significantly m
Page 113 and 114:
3 2 1 0 Canonical Variate 2 -1 -2 R
Page 115 and 116:
8 Anterior Discrepancy (ADisc) 6 4
Page 117 and 118:
40 Incisor Aspect Ratio (IAR) 30 20
Page 119 and 120:
1.5 Incisor Segment Depth (ISD) 1 0
Page 121 and 122:
more stable (i.e., the mean change
Page 123 and 124:
Molar Correction (MC) 10 8 6 4 2 0
Page 125 and 126:
Anterior Segment Width (ASW) 1 0 -1
Page 127 and 128:
final vertical positions. This phas
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decreased in both arches during the
Page 131 and 132:
Figure 5-1. Plot of average Incisor
Page 133 and 134:
Based on the present results, the u
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these variables indicate more anter
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and the hassle associated with plac
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Figure 5-2. Scatter-plot graph refl
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stability?” and “for how long?
Page 143 and 144:
About two-thirds (64%) of the corre
Page 145 and 146:
Baume LJ, Horowitz HS, Summers CJ,
Page 147 and 148:
Case CS. Techniques and principles
Page 149 and 150:
Glenn G, Sinclair PM, Alexander RG.
Page 151 and 152:
Joondeph DR. Retention and relapse.
Page 153 and 154:
Littlewood SJ, Millett DT, Doubleda
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Ormiston JP, Huang GJ, Little RM, D
Page 157 and 158:
Rosenstein SW, Jacobson BN. Retenti
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Steadman SR. A philosophy and pract
Page 161 and 162:
Zachrisson BU, Büyükyilmaz T. Bon
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Table A-1. Descriptive statistics a
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Table A-2. Descriptive statistics a
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Table A-3. Descriptive statistics f
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Page 171 and 172:
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APPENDIX B. ANCOVA TESTS OF THE COM
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Table B-1. Continued. Sex Retention
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Page 179 and 180:
Page 181 and 182:
Page 183 and 184:
Page 185 and 186:
Table C-1. Results of ANCOVA tests
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Page 195 and 196:
Page 197 and 198:
Table D-1. Descriptive statistics,
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Table E-1. Two-way ANOVA tests eval
Page 205:
VITA Mark Owens was born on January
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EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...

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