EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...

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study occurred during the active phase of treatment, the results suggest that if relapse does occur, it is most likely to occur soon after treatment and can be expected to diminish thereafter. Long-term postorthodontic changes were interpreted as a combination of orthodontic relapse and normal growth and aging processes. At the University of Washington, Little, Riedel, and Årtun (1988) evaluated 31 four-premolar extraction cases from a previous study (Little, Wallen, and Riedel 1981) at a minimum of 20 years posttreatment. Variables such as Angle’s classification, patient age at the beginning of treatment, sex, overbite, overjet, arch width, arch length were analyzed at each examination. The studies evaluated mandibular anterior alignment. The secondary goal was to describe treatment and posttreatment changes and search for predictors and associations of stability. Results indicated that crowding continued to increase during the 10- to 20-year postretention phase. The authors concluded that, “Cases responded in a diverse unpredictable manner with no apparent predictors of future success when considering pretreatment records or the treated results” (p 423). Severity of Pretreatment Malocclusion and Posttreatment Stability Physiologic recovery has been described as, “The type of posttreatment changes that represent a rebound or reversion toward the original malocclusion” (Horowitz and Hixon 1969, p 4). Example of changes include: rotations, lower anterior crowding, collapse following arch expansion, molar relationship changes, and recurrence of overbite (or open-bite) and overjet. It could be assumed that cases who demonstrate an increased severity of pretreatment malocclusion will also exhibit a greater degree of posttreatment relapse. A recent study at the University of Washington involving 86 patients was undertaken to identify factors associated with stability (Ormiston et al. 2005). The sample was divided into 2 groups according to whether their treatment results were deemed stable or unstable based on the PAR index and irregularity index. The authors found the initial severity of malocclusion to be negatively correlated with posttreatment stability. They concluded that patients with more severe index scores before treatment tended to be less stable. Incisors that are labially inclined prior to treatment tend to exhibit less long-term crowding (Sanin and Savara 1973; Gilmore and Little 1984). Class II, division 1 malocclusions have been reported to exhibit around twice as much relapse in overbite correction as Class II, division 2 malocclusions according to Bresonis and Grewe (1974), who analyzed 53 orthodontically treated cases at 5 25
years postretention. Årtun et al. (1996) found that narrow pretreatment intercanine width and increased pretreatment Incisor Irregularity associated with Class II, division 1 malocclusions were significant predictors of relapse in the mandibular incisors. However, other studies (Bishara et al. 1973; Elms et al. 1996) have found no greater relapse associated with Class II division 1 malocclusion cases when compared with other types of malocclusions. Prevention of Post-Orthodontic Relapse The proposed rationale for retaining teeth in their treated position is: to allow time for periodontal and gingival reorganization; to minimize changes from physiologic growth; to permit neuromuscular adaptation to the corrected tooth position; and to maintain unstable tooth position, if such positioning is required for reasons of compromise or esthetics (Blake and Bibby 1998). Controversy involves questions such as, “Just how should the teeth be retained,” and “For how long a period of time should they be retained?” The following section describes various methods of retention and reviews opinions regarding recommended retention periods. Types of Mechanical Retention The purpose of posttreatment retention, according to Angle (1907, p 263), is that “After malposed teeth have been moved into the desired position they must be mechanically supported until all the tissues involved in their support and maintenance in their new positions shall have become thoroughly modified, both in structure and in function, to meet the new requirements.” Proffit (1993) has described various forms of mechanical retention as removable, fixed, passive, or active, mechanical retention can generally be broadly classified based on whether or not the retainer is intended to be taken in and out of the mouth by the patient. Both fixed and removable forms of retention continue to be popular means of maintaining postorthodontic treatment results. Since 1925, the standard maxillary retaining device has been the removable Hawley retainer, while in the lower arch, the cemented canine-to-canine retainer has been popular for possibly a longer period of time (Muchnic 1970). Removable Retention Of the current methods, the traditional Hawley-type appliance (Hawley 1919) is probably by far the most commonly employed. This removable appliance can be fabricated for both the maxillary and mandibular arches and 26
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 Sakols 1982; Vaden et al. 1997;
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
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occlusal issues are tolerated by bo
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40 35 30 FMA (degrees) 25 20 15 10
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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
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Figure 4-8. Box plot of the distrib
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which a Class I relationship was no
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Figure 4-11. Plot of mean Curve of
Page 105 and 106:
Figure 4-13. Box plot of the distri
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Table A-4 addresses the question of
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Figure 4-16. Bar chart of the avera
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only sample changed significantly m
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3 2 1 0 Canonical Variate 2 -1 -2 R
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8 Anterior Discrepancy (ADisc) 6 4
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40 Incisor Aspect Ratio (IAR) 30 20
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1.5 Incisor Segment Depth (ISD) 1 0
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more stable (i.e., the mean change
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Molar Correction (MC) 10 8 6 4 2 0
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Anterior Segment Width (ASW) 1 0 -1
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final vertical positions. This phas
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decreased in both arches during the
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Figure 5-1. Plot of average Incisor
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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?
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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
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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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Page 185 and 186:
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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