EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...

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12 10 Incisor Irregularity (II) 8 6 4 2 0 -2 Fixed Retention Remove Figure 4-25. Box plot of the amount of relapse in mandibular Incisor Irregularity (II) dependent on type of retention. That is, the increase in irregularity was statistically greater on average in the removable group ( x = 2.3 mm) than in the fixed group ( x = 1.5 mm) during the posttreatment interval. 109
more stable (i.e., the mean change was close to zero) compared to greater change in the removable sample. The amount of change in the fixed sample was 1.46 mm versus 2.30 mm in the removable group. Maxillary Intermolar Width (Table C-9) also shows up as a significant variable (P = ~ 0.01). The sample with fixed retention experienced slight expansion, while cases with just Hawley retainers experienced slight constriction (Figure 4-23). Maxillary Intermolar Width decreased in both groups, but significantly more so in the group with just removable retainers. It is difficult to determine why this effect on maxillary intermolar width shows up between the groups during the recall period. Any attempts at explaining this difference would be purely conjecture. Incisor segment ratio (Table C-6) shows up as significant variable (P = ~ 0.01). In the sample that received just the Hawley retainers, incisor segment ratio is closer to zero, which indicates that the incisor arch form became more curved and decreased in width after treatment as viewed occlusally (Figure 4-21) more so than in the fixed retention sample. Incisor Aspect Ratio (Table C-7) reveals only borderline significance (P = ~ 0.05). Figure 4-22 illustrates that Incisor Aspect Ratio is greater in the fixed group, indicating that incisors remained more upright in cases retained with a fixed retainer as compared to those retained with a Hawley retainer following treatment. Incisor segment depth (Table C-13) shows up as significant variable (P = ~ 0.01). Figure 4-24 illustrates that the sample with fixed retention was more stable (i.e., the median hovered on zero) compared to the removable sample. Extraction Pattern Three different extraction patterns proved common enough in the data to allow for statistical analysis (Appendix E). These are (1) nonextraction, (2) extraction of maxillary and mandibular first bicuspids (4-4/4-4), and (3) extraction of maxillary first bicuspids and mandibular second bicuspids (4-4/5- 5). Table E-1 lists the results of two-way ANCOVA tests evaluating whether the amount of relapse was associated with a particular extraction pattern while controlling for the time out of treatment. That is, there is little chance that the occlusion is continuing to change since no one less than 10 years out of treatment was included. Still, partly out of curiosity and partly to confirm the situation, time-out-of-treatment was used as the covariate. In fact, 3 of the 33 variables did show a significant age effect (i.e., ISR, LCW, and ISD). 110
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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
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
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: 1.5 Incisor Segment Depth (ISD) 1 0
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 and 130: 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
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 169 and 170: Table A-4. Descriptive statistics f
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Table A-5. Descriptive statistics f
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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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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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