EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...

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10 8 Molar Relationship 6 4 2 0 Fixed Retention Remove Figure 4-9. Box plot of molar relationship at the end of treatment in the two retention groups. Notice that 2 cases, one in each group, were treated to a Class II molar relationship, which accounts for the outliers at the top of the graph. 89
which a Class I relationship was not fully achieved during treatment were more likely to be put into a fixed retainer. Analysis of the long-term recall records (Table A-3) reveals four variables that are predictive of the kind of retention used. The Curve of Spee continues to be an important predictor throughout the recall period. There was a moderate increase in the Curve of Spee in the fixed group (Figures 4-10 and 4-11), whereas it nearly doubled in the removable group following treatment. According to the probability values, Incisor Depth exhibited the largest statistical difference between the two groups (Figure 4-12), with a greater depth (24 mm) in the fixed group than the removable group (20 mm). This finding was unanticipated and difficult to explain. It is interesting that total chin no longer exhibits significance at the recall examination. The difference between these two groups was relatively the same at the start of treatment, persisted throughout treatment, but then disappeared years following orthodontic treatment. This suggests that orthodontics had little effect on this variable, and that with the normal growth and development that typically follows treatment, the previous statistical differences seen in this measurement were resolved in time. Mandibular Incisor Irregularity exhibits a statistically significant difference between groups at the recall examination (P = 0.0104 by two-way ANOVA; Figure 4-13). This is a key finding since Incisor Irregularity often is used as an important measure of stability because it is so obvious to the patient. The mean of the fixed group was 1.92 mm and the mean of the removable group was 2.53 mm. However, clinically this difference is pretty small and amounts to only about 0.6 mm. One additional potential benefit of fixed retention, as evident from Figure 4-13, is that visually, the fixed retainers kept outliers to more of a minimum, as you can see that the points in the fixed group are more closely related to the median than those of the removable group. This proposed benefit is purely conjecture and might be difficult to support statistically. The fourth variable that differed significantly at the recall examination (Table A-3) is IMPA, and this is graphed in Figure 4-14. By two-way ANOVA, the P value is 0.0302. However, the difference is not visually apparent in the graph, where the mean of the group with fixed retention ( x = 91.42) is significantly higher than in the Hawley-only group ( x = 89.45). In other words, the lower incisors are a bit more flared in the group with fixed retention. It was difficult to determine why this difference occurs at the recall examination, as this difference was not present at the end of treatment. 90
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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
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
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: Figure 4-8. Box plot of the distrib
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 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.
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Joondeph DR. Retention and relapse.
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Littlewood SJ, Millett DT, Doubleda
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Ormiston JP, Huang GJ, Little RM, D
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Rosenstein SW, Jacobson BN. Retenti
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Steadman SR. A philosophy and pract
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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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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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