EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...

More documents

Recommendations

Info

primarily a measure of how flared (proclined) the maxillary incisors are when viewed occlusally. When the incisors are upright and essentially perpendicular to the occlusal plane, Incisor Depth will be minimized, so greater Incisor Depth in the fixed-retention sample suggests that orthodontists were somehow attuned kind of retention they received. Amount of Relapse The prior sections identified several variables that exhibit statistically significant differences between the types of retention. In this section, we turn attention to assessing the effect that variables had on the extent of relapse. Appendix C lists the results of testing each of the 32 variables to evaluate whether the amount of change depends on the type of retention, with the patient’s sex and time out of treatment as covariates. A word of explanation will help clarify the thought behind these statistical tables. Retention (Hawley versus fixed) is the key variable, and the other variables in the model are used simply to control for known sources of confounding variation. “Sex” was included merely to absorb the variance due to men being larger than women. Time (i.e., years out of treatment) was included to control for the variability in the duration of time available for relapse. In fact, “time” is rarely significant because most relapse seems to occur soon after treatment (Horowitz and Hixon 1969), so, at a minimum of one decade out of treatment the full rebound due to treatment probably has occurred. The other four terms in the model are the standard first- and second-order interaction terms (e.g., Winer et al. 1991) that are included to check for additivity of the main effects. Put simply, additivity—that the main effects respond in proportional fashions—is a necessary assumption; if additivity does not occur (i.e., a significant interaction effect) then the model is biased and yields unreliable results. Of the 32 variables, six showed a significant relationship between the amount of relapse and the kind of retention. Figures 4-20 through 4-25 provide graphic representations of the group differences for these six variables. Anterior discrepancy (Table C-1) exhibits a statistically significant difference depending on type of retention (P = ~ 0.02). Figure 4-20 discloses that using fixed retention provides greater stability, although clinically small, following treatment. Mandibular Incisor Irregularity (Table C-17) shows up as a significant variable (P = ~ 0.01). Figure 4-25 shows that the sample with fixed retention was 103
8 Anterior Discrepancy (ADisc) 6 4 2 0 -2 Fixed Retention Remove Figure 4-20. Box plot of the amount of relapse in Anterior Discrepancy (ADisc) dependent on type of retention. On average, treatment change in anterior discrepancy was significantly greater in the removable sample, though clinically less than 1.0 mm. 104
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 and 38:
years postretention. Årtun et al.
Page 39 and 40:
adjustment, if necessary. This abil
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
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: 3 2 1 0 Canonical Variate 2 -1 -2 R
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.
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:
Page 171 and 172:
Page 173 and 174:
APPENDIX B. ANCOVA TESTS OF THE COM
Page 175 and 176:
Table B-1. Continued. Sex Retention
Page 177 and 178:
Page 179 and 180:
Page 181 and 182:
Page 183 and 184:
Page 185 and 186:
Table C-1. Results of ANCOVA tests
Page 187 and 188:
Page 189 and 190:
Page 191 and 192:
Page 193 and 194:
Page 195 and 196:
Page 197 and 198:
Table D-1. Descriptive statistics,
Page 199 and 200:
Page 201 and 202:
Page 203 and 204:
Table E-1. Two-way ANOVA tests eval
Page 205:
VITA Mark Owens was born on January
show all

EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?