EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...

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acceptable postretention stability at the long-term (80%) than previously reported (Little et al. 1981, 1988). The authors attributed much of this stability to meeting specific evidence-based treatment objectives during treatment. The present study and others, as reviewed by Boley (2007, p 16), also document that acceptable long-term stability is possible and can be linked to several common characteristics of these “satisfactory stable” samples—including minimal alteration of the mandibular arch form and the retraction and uprighting or maintenance of mandibular incisors in their original position (Boley et al. 2003). Mandibular Incisor Irregularity often is used as an important indicator of a case’s stability (Little 1977), partly because it is a condition obvious to the patient. Figure 5-1 illustrates that group averages do not differ at the pretreatment examination, but at the end of treatment, the fixed group has a significantly greater amount of irregularity. However, by the recall examination, this difference not only disappears, but becomes statistically significant in the other direction, as the removable group now has a statistically significant greater Incisor Irregularity than does the fixed group. This is also evident in the significant difference noted in the rate of change of Incisor Irregularity between the two groups following treatment (Table A-5). Patients receiving only Hawley removable retainers displayed ~ 2.5 mm of Incisor Irregularity, while patients receiving an upper Hawley retainer in combination with a temporary fixed lower retainer displayed only ~ 1.9 mm irregularity. This difference between the groups (~ 0.6 mm) at the recall examination was found to be statistically significant, but from a clinical standpoint, these differences are minimal, and likely would not be detected by the patient or practitioner. Overall incidence of long-term stability of both groups ( x ~ 2.2 mm) was greater than previously reported by most studies (Table 5-1). Other statistically significant changes after treatment occurred in Incisor Segment Ratio and Incisor Aspect Ratio. These two ratios reflect the proclination of the lower incisors. There was a net decrease in Incisor Segment Ratio ( x = -0.8 for the removable group), while there was a net increase ( x = 0.7 for the fixed group). There was a greater positive change in Incisor Aspect Ratio in the fixed retention group ( x = 5.8 mm) compared to the removable group ( x = 3.1 mm). Considered together, these changes suggest that the lower incisors tipped forward more in the removable group than in the fixed group. This does not necessarily mean that alignment deteriorated, only that there was a greater proclination. There was also a greater decrease in maxillary intermolar width during this period in the removable group than in the fixed group. It is unclear why this might be. 119
Figure 5-1. Plot of average Incisor Irregularity, by group, at the three examinations. Though statistically significant, the fixed retention appliance only enhances stability by an average of 0.6 mm at the long-term recall examination. 120
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EFFICACY OF TEMPORARY FIXED RETENTI
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DEDICATION This thesis is dedicated
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ABSTRACT Instability of the occlusi
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CHAPTER 5. DISCUSSION .............
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LIST OF FIGURES Figure 3-1. All cas
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Figure 4-14. Box plot of the distri
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Joondeph and Riedel (1994, p 908) d
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Strang (1952, p 794) claimed that
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malocclusion must be maintained if
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e aimed at maintaining, in most ins
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three time intervals: during treatm
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mechanical treatment does not neces
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elation, the masticatory system wil
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exerted on the denture from the buc
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In summary, the variance in tongue
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Sinclair and Little (1983, p 114) a
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Study and 43 orthodontically treate
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and Sakols 1982; Vaden et al. 1997;
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years postretention. Årtun et al.
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adjustment, if necessary. This abil
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Duration of Retention The premise i
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The reduction in tooth structure of
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4. The most stable position of the
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CHAPTER 3. MATERIALS AND METHODS Sa
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The present sample consisted of the
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Figure 3-2. Illustration of how mol
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Figure 3-3. Illustration showing di
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Figure 3-5. Illustration showing mi
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Figure 3-6. Illustration showing an
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Figure 3-8. Illustration showing in
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34. LR3 cusp tip point. 35. Right d
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Figure 3-10. Illustration showing o
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Figure 3-11. Illustration of Inciso
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3. Go, Gonion (anatomic): The most
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Figure 3-13. Depiction of the angle
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Figure 3-15. Illustration of the me
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Figure 3-17. Illustration of the me
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Figure 3-19. Illustration of the an
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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
Page 95 and 96: larger ANB at the recall examinatio
Page 97 and 98: 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
Page 111 and 112: 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
Page 129: decreased in both arches during the
Page 133 and 134: Based on the present results, the u
Page 135 and 136: these variables indicate more anter
Page 137 and 138: and the hassle associated with plac
Page 139 and 140: Figure 5-2. Scatter-plot graph refl
Page 141 and 142: 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
Page 155 and 156: Ormiston JP, Huang GJ, Little RM, D
Page 157 and 158: Rosenstein SW, Jacobson BN. Retenti
Page 159 and 160: Steadman SR. A philosophy and pract
Page 161 and 162: Zachrisson BU, Büyükyilmaz T. Bon
Page 163 and 164: Table A-1. Descriptive statistics a
Page 165 and 166: Table A-2. Descriptive statistics a
Page 167 and 168: Table A-3. Descriptive statistics f
Page 173 and 174: APPENDIX B. ANCOVA TESTS OF THE COM
Page 175 and 176: Table B-1. Continued. Sex Retention
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Table B-4. Continued. Sex Retention
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Table B-5. Continued. Sex Retention
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Table C-1. Results of ANCOVA tests
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Table D-1. Descriptive statistics,
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Table E-1. Two-way ANOVA tests eval
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VITA Mark Owens was born on January
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EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...

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