EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...

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y extracting bicuspids in an effort to circumvent the arch expansion that was created as a result of his previous non-extraction treatment. Tooth extraction allowed him to: create the space necessary to relieve dental crowding; position the mandibular incisors “upright over basal bone,” into what he considered their most stable position; and prevent the expansion of the dental arch. Strang (1949) also opposed expansion of the dental arches and claimed that expansion of the dental arches would not remain stable. Strang (1949, p 17) stated, “There is no question in my mind that denture expansion as a treatment procedure in the correction of malocclusion should be discarded and every effort should be directed toward preserving the muscular balance that is the most important factor in establishing tooth position.” Strang (1949, p 16) asserted that in cases where it was impossible to align the mandibular incisor teeth in an upright position over basal bone without the buccal movement of the cuspids and posterior teeth, the reduction of tooth material by the “extraction of dental units is definitely indicated.” Strang (1952) went on to assert that pretreatment intercanine width dictated the limit of acceptable denture expansion that would allow for stability of the finished result. In contrast, Douglas Walter (1953) proposed that a crowded or otherwise deformed pretreatment arch did not necessarily represent its true size or form and that maintaining arch dimension was no guarantee in achieving a stable posttreatment result. Walter based his opinions on 102 non-extraction cases ranging in age from 6 to 36 years of age. Pretreatment dental casts were taken of all 102 cases. These were compared to 34 dental casts that were available immediately after active treatment and to 90 dental casts available from intervals ranging from one to 13 years (average of 2.5 years) after all retention had been removed. Bilateral measurements were made between every pair of teeth of both arches and arch length was also recorded by measuring the distance along the arch between the mesial of each first molar. Walter found that permanent expansion of arch widths occurred in 88% of the patients, and in some of these cases, expansion continued past the active treatment phase. Walter found that 12% of expanded cases did return to their more narrow pretreatment arch form. Similar findings were noted for arch length as well. Walter claims that all cases maintained the occlusal result gained in treatment and that all but 10% of the cases could be viewed as highly successful cases. The conclusions drawn from this study was that a wide variety of results can be found when arch dimension is altered during treatment and that preservation of arch dimension is no guarantee of future stability. In his review of the literature in 1960, Riedel concluded that arch form, particularly in the mandibular arch, should not be permanently altered by orthodontic treatment. Instead, Riedel (1960, p 181) asserted, “Treatment should 7
e aimed at maintaining, in most instances, the arch form presented by the original malocclusion.” Bishara et al. (1973) examined a sample of 30 treated cases from the University of Iowa, Department of Orthodontics. All patients were treated with the edgewise appliance and required first premolar extractions. The mean postretention time was 14.8 months, with a range from 6 months to 48 months. Pretreatment, posttreatment, and postretention dental casts were used to measure maxillary and mandibular intercanine width. The results indicated that in cases where mandibular intercanine expansion occurred, the mean percentage relapse was 71%. However, where intercanine expansion occurred in the maxillary arch, the mean percentage relapse was only 3%. Herberger (1981) concluded that some patients can be treated with canine expansion and that this expansion can be maintained. Herberger looked at the stability of mandibular intercanine width at various retention periods. He based his study on a sample of 56 of his own patients whom he treated nonextraction, and cases were divided according to the length of retention, namely 4, 5, or 6 years. The intercanine widths of all patients were measured from casts at pretreatment, posttreatment, and at postretention. Of the 56 cases, 52 showed mandibular intercanine expansion, 2 remained unchanged, and 2 were constricted 1 mm during treatment. Most cases (38 patients) remained expanded to some degree, while 18 lost an average of 0.8 mm from their initial intercuspid width. Herberger found no case in which the mandibular intercuspid width increased after retention. Little, Wallen, and Riedel (1981) assessed 65 patients who had been treated with first premolar extractions and traditional edgewise mechanics at a minimum of 10 years posttreatment. Retention methods were varied. Arch width decreased an average of 2 mm after retention, regardless of treatment expansion or constriction. The researchers concluded (p 357) that, “Arch width change during treatment was a poor predictor of long-term crowding, the degree of expansion or constriction having little association with postretention alignment.” Arch length was also found to decrease during treatment due to extraction, but also found to decrease during the postretention period as well. Researchers continue to explore the ramifications associated with the expansion of the dental arches during orthodontic treatment. One possible explanation for the continued interest in canine expansion is the fact that canine expansion is responsible for creating usable space in the transverse dimension to correct crowding (Gianelly 2006). According to Ricketts et al. (1982), 1 mm of intercanine width expansion results in a 1 mm increase in arch perimeter, while a 8
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: malocclusion must be maintained if
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
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Figure 3-19. Illustration of the an
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Figure 3-21. Illustration of the up
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Figure 3-22. Illustration of the to
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Figure 3-24. Illustration of the po
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the “older” Tweed force system,
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The null hypothesis is: There was n
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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
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
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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
Page 117 and 118:
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
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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.
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Littlewood SJ, Millett DT, Doubleda
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Ormiston JP, Huang GJ, Little RM, D
Page 157 and 158:
Rosenstein SW, Jacobson BN. Retenti
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Steadman SR. A philosophy and pract
Page 161 and 162:
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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Page 171 and 172:
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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 181 and 182:
Page 183 and 184:
Page 185 and 186:
Table C-1. Results of ANCOVA tests
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Page 195 and 196:
Page 197 and 198:
Table D-1. Descriptive statistics,
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Page 201 and 202:
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Table E-1. Two-way ANOVA tests eval
Page 205:
VITA Mark Owens was born on January
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EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...

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