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Orthodontic rotational relapse: prevalence and prevention

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Orthodontic rotational relapse: prevalence and prevention

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1

Orthodontic Rotational
Relapse: Prevalence and
Prevention
By
Katie Wong
May 2016

A thesis presented to the faculty of the USC Graduate School in partial fulfillment of the
requirements for the Masters of Science in Craniofacial Biology degree

2

Table of Contents

I. Abstract 3
II. Introduction 4
III. Literature Review 4-23
a. Causes of relapse 4-7
b. Determinants of orthodontic stability 7
c. Retention methods 8-9
d. Evidence-based use of retainers 9-12
e. Relapse prevention 12-14
f. Expected changes over time 14-15
g. Records to assess rotational tooth movement 15-17
h. Targets of orthodontic treatment- Scoring systems 17-20
i. Assessment of rotational tooth movement- The literature 20-22
j. Study objective 22-23
IV. Materials and Methods 23-26
V. Results 26-33
VI. Discussion 33-39
VII. Conclusions 39-40
VIII. References 41-45
IX. Appendix 46-54
a. Case examples 46-54

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I. Abstract
Background: Relapse is an inevitable soliloquy of orthodontic treatment without proper
retention. A better knowledge of how teeth relapse after appliance removal may help the
orthodontic practitioner in choosing the most appropriate retention and relapse prevention
therapy. Purpose: The aim of this study is to accurately assess the prevalence of
rotational relapse that takes place between appliance removal and retainer delivery to
determine any patterns in relapse direction. Methods: Dental models from 13
consecutively de-bonded patients were compared at three time points: initial
malocclusion, day of appliance removal, and 6-16 days later at retainer delivery. Initial
models and models from the day of appliance removal were visually assessed to
determine how the teeth were rotated into their corrected positions. To observe the
direction these teeth relapsed, models from appliance removal and retainer delivery were
digitally scanned and superimposed to create a 3D color map showing changes that
occurred between the two time points. Results: Overall among the teeth that were
moved orthodontically, the majority had no rotational relapse. The data suggests that
teeth are nine times more likely to relapse in the opposite direction of orthodontic rotation
than in the same direction. A large proportion of the teeth sampled were not moved
orthodontically and did not relapse after appliance removal. Surprisingly, a small
proportion of teeth relapsed even when not moved orthodontically from their initial
malocclusion. Conclusion: Using the described methods, it is possible to conclude some
trends in the direction of orthodontic rotational relapse. While most teeth will not relapse
between appliance removal and retainer delivery, the orthodontic practitioner should be
most aware of the potential for relapse in the opposite direction of orthodontic rotation.

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II. Introduction
Much attention has been given to the changes that occur in dental position after
orthodontic treatment. When these changes approach their original pretreatment tooth
positions, relapse is said to have occurred. This relapse potential is well described in the
literature, yet it is still a challenge to predict or prevent after orthodontic treatment[1-6].
Various types of retention are available to orthodontists in an attempt to minimize this
unwanted post-treatment movement. A better knowledge of how teeth relapse after
appliance removal may help the orthodontic practitioner in choosing the most appropriate
retention and relapse prevention therapy. Many studies have described the potential for
relapse and need for long-term retention, but few have specifically examined rotational
relapse. The aim of this study is to accurately assess the incidence of rotational relapse
that takes place between appliance removal and retainer delivery in order to identify any
patterns in relapse direction that may improve relapse prevention protocols.

III. Literature review
a. Causes of relapse
Aligned teeth have a tendency to relapse because of: the elasticity of gingival fibers,
intraoral pressures from the cheek, lip, and tongue, and differential jaw growth (Figure I).

5

Figure I: Major causes of orthodontic relapse (Adapted from Proffit).

Teeth are subject to a dynamic equilibrium of forces from the cheeks, tongue, lips, and
periodontal ligament[7]. These forces act together to determine the position in which
teeth are most stable. These pressures still exist after aligning teeth orthodontically and
may act to push teeth back to their pre-treatment positions if the equilibrium has been
disrupted.

Many studies have described the remodeling of the supporting tissues that occurs before,
during, and after orthodontic tooth movement [8]. There are two soft-tissue periodontal
entities that may influence the stability of the teeth following orthodontic movement: the
supra-alveolar group of fibers and the principal fibers of the periodontal ligament[9].
Turnover of the PDL is appreciably increased in response to orthodontic forces. When
force is applied to a tooth the PDL is compressed on one side, compacting collagen fibers

6

and decreasing blood flow; Stretching of collagen fibers and increased blood flow occurs
on the tension side[10, 11]. In turn, chemical messengers are released and cells are
activated leading to pressure-induced resorption and tension-induced deposition of
bone[12]. While the rate of tooth movement is determined by bone removal on the
pressure side, stability is determined by remodeling on the tension side. The remodeling
of the principal fibers on the tension side is related to the direction of tooth movement
and results in production of new fibers only in that direction. During retention the
stretched PDL fibers become relaxed and rearranged, and bone is deposited providing
support for the new tooth position[13].

While the principal fibers of the PDL will rearrange themselves after a period of 8 to 9
weeks, the supra-alveolar fibers may remain stretched over a longer period and are thus
more of a concern for relapse[8, 14]. Experiments by Reitan on rotation and retention of
rotated teeth in young dogs reveal that some of the gingival fiber bundles will remain
displaced and stretched even after a retention period of 232 days[10]. This fiber group
may remain stretched because they attach to a movable fibrous system, rather than to
bone that is readily remodeled. The fibrous system is slow to remodel because its main
function is to protect the alveolar process and conserve the interproximal tooth contact.
Additionally, Elastic fibers are present in the free gingiva and will enter into action the
moment forces on the tooth are released, acting to pull teeth back to their pre-treatment
positions. Thus, if teeth are not retained until this remodeling of the bone, gingiva, and
PDL is complete, relapse is likely to occur.

7

Even after this remodeling, teeth are subjected to variable oral muscular forces that have
the potential to alter their positions. Continuation of jaw growth after active orthodontic
treatment may contribute to these forces. When the mandible grows forward or rotates
downward, a lingual crown force is exerted on the teeth by the lip. Class III patients or
those with skeletal open bite problems are strongly associated with relapse of lower
incisor alignment due to these forces[7]. The goal of life long retention is to maintain the
alignment of teeth even in the presence of changing intraoral pressures.

b. Determinants of orthodontic stability

There is currently insufficient research data on which to base clinical retention
protocols[15]. Generally, extraction cases are more stable than arch-development cases,
but it is impossible to predict on an individual basis. Expansion of the inter-canine width
is one of the greatest predictors of relapse [16]. Despite this knowledge, teeth should not
be extracted based on these generalizations. Many orthodontists implement a protocol of
interproximal reduction of the mandibular anterior teeth following orthodontic alignment
to broaden the contact and increase long-term stability [17]. This procedure is not related
to an increased incidence of caries[18] or gingival or periodontal problems[19]. Alone,
however, interproximal reduction is not sufficient to assure the permanence of the
orthodontic treatment results.

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c. Retention methods

Studies have shown that 40% to 90% of orthodontic patients have unacceptable dental
alignment 10 years after treatment[13]. Based on these considerations, it is important that
some sort of long-term retention be utilized. Fixed or bonded retainers are used in
situations where prolonged retention is necessary due to inherent intra-arch instability.
There are currently three generations of fixed retainers available: Plain blue Elgiloy wire
with a loop at each terminal end for added retention, multistranded wire of similar
diameter, and round 0.032 inch stainless steel or 0.030 inch gold coated wire[20]. Fixed
retainers can be bonded to two teeth, most often the canines, or to three or more teeth,
frequently all lower incisors and canines and all upper incisors[21]. Indications for a
bonded canine-to-canine retainer include: Severe pretreatment lower incisor crowding or
rotation, planned alteration in the lower intercanine width, advancement of the lower
incisors during active treatment, after nonextraction treatment in mildly crowded cases,
after correction of deep overbite[22]. Zachrisson listed the following indications for use
of flexible wire retainer: closed median diastema, spaced anterior teeth, adult cases with
potential post orthodontic tooth migration, after mandibular incisor extractions, severely
rotated maxillary incisors, and palatally impacted canines[23].

Removable retainers can be an acrylic/wire type of appliance, including the Hawley-type
(HR) and wrap-around, a clear vacuum formed retainer (VFR), or other design. The
follow includes a summary of the benefits and drawbacks of each:
1. Hawley retainers: rigid, yet adjustable, and allow for some settling of the

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occlusion[15]. Less esthetic than other retainers.
2. Clear vacuum formed retainers: esthetic, easily fabricated but with occlusal coverage
that does not allow settling of occlusion.
3. Other designs: positioners and silicone-based retainers

Figure II: Examples of fixed and removable retainers: (a) canine only mandibular fixed
retainer, (b) fixed retainer bonded to mandibular canines and incisors, (c) removable
Hawley retainers, (d) removable clear vacuum formed retainer

d. Evidence-based use of retainers

There are two phases of retention: the retention phase and the post-retention phase. In the
first phase, the final alignment achieved by orthodontic treatment is maintained by full
time retainer wear until the periodontal tissues have remodeled. This is generally
completed within a year of appliance removal[24]. The second phase continues after this
remodeling and includes indefinite part-time retainer wear.

b
.

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There are many published studies comparing VFRs with HRs[25-27]. Rowland et al
conducted a prospective, randomized clinical trial and concluded that VFRs were more
effective than HRs in retaining the correction of the maxillary and mandibular labial
segments[25]. Demir et al

also determined that VFRs were more efficient in retaining the
anterior mandibular teeth during a 1-year retention period. However, a recent
retrospective, randomized, double-blind comparison study reported no statistically or
clinically significant differences in the effectiveness of HRs and VFRs in maintaining
specific arch-form features after orthodontic treatment[28].

These conflicting results may be due to the fact that the success of removable retainers
depends almost completely on good compliance of the patient. A survey conducted at the
University of Kentucky in 2008 evaluated patient compliance with removable orthodontic
retainers[29]. The authors found that the patient’s age, sex, amount of time since
debonding, understanding of proper compliance, and retainer type all significantly
influenced patient compliance. The study also concluded that patients were more
compliant with vacuum-formed retainers than Hawley retainers initially after debonding,
but compliance decreased at a much faster rate than with Hawley retainers. Thus, in the
long run, patients were more compliant with Hawley retainers than with vacuum-formed
retainers. Finally, this study found that very few patients wore their retainers as instructed
at 5 years after debonding.

Fixed retainers remove the need for patient compliance. Those bonded to all incisors are
capable of retaining the alignment of all the teeth involved[28]. Canine-only bonded

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retainers are effective in maintaining post-orthodontic alignment in most patients, but
some will have a mild increase in incisor irregularity due to some freedom of movement
of the non-bonded teeth[15, 30-32].

Booth and colleagues examined the health effects and effectiveness of very long-term
fixed retention[33]. In a group of 60 patients examined at a minimum of 20 years after
orthodontic de-bonding, 45 were still wearing a canine-only bonded retainer and 15 were
not. Gingival index scores demonstrated no detrimental effects to the mandibular anterior
gingiva. Eighty percent required none or one repair of the retainer. It has been proposed
that a retainer could actually have positive effects on patient’s hygiene in terms of
motivation[34]. This concurs with Booth’s sample, in which patients who had retainers
removed had worse hygiene than those who kept their retainer in place. However, Pandis
and colleagues reported that patients with long-term fixed retention accumulated more
calculus, and emphasized the need to assess oral hygiene when deciding whether to bond
a fixed retainer[35].

Scheibe and Ruf retrospectively assessed 1,062 patients with lower bonded retainers[36].
One-third of the sample experienced retainer failure over an average retention period of 3
years with canine-only bonded retainers being less troublesome than those bonded to
every anterior tooth. This discrepancy was contributed to operator technique. Zachrisson
and colleagues reported a success rate of 95% after a follow up of 1-10 years for various
bonded retainers[23].

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Based on the above, it seems that with good hygiene, fixed retainers do not cause long-
term gingival or periodontal problems. Their long-term efficacy and success is related to
the operator technique[28].

The orthodontist’s choice of retention protocol is an individual decision. In a survey of
632 US orthodontists conducted by Pratt et al, respondents reported predominant use of
Hawley (47%) and VFRs (41%) for retention in the maxillary arch, and fixed retention
(42%) in the mandibular arch [37]. Despite the predominant use of Hawley retainers, this
study concluded that there is an overall shift toward the use of VFRs and fixed retainers.
Keim et al conducted surveys regarding orthodontic trends between 1986 and 2008[38].
The results of this study concurred with the trends toward VFRs and fixed retention, with
a corresponding decrease in the use of Hawley retainers.

e. Relapse prevention

Several techniques for prevention of relapse have been suggested including
overcorrection, low-level laser irradiation, and supracrestal fiberotomy[39-42]. The
following is a summary of a small sample of what has been publish on the efficacy of
these treatments.

A long-term prospective evaluation of the circumferential supracrestal fiberotomy in
alleviating orthodontic relapse by Edwards used Little’s “irregularity index” to
quantitatively record relapse over a 15 year period[42]. There was a highly significant

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difference between the mean relapses of the control and the CSF cases. The surgical
procedure appeared to be somewhat more effective in alleviating pure rotational relapse
than in labio-lingual relapse, indicating that this therapy should be considered for
rotational relapse prevention. Overall, the CSF procedure was shown to be more
successful in reducing relapse in the maxillary anterior segment than in the mandibular
anterior segment. No clinically significant increase in the periodontal sulcus depth nor
decrease in the labially attached gingiva of the CSF teeth was observed at 1 and 6 months
following the surgical procedure.

Figure III: Circumferential supracrestal fiberotomy

Low-level laser irradiation is a process that involves laser application to the gingiva to
alter cellular activity. A recent study on the effect of LLLT on the rate and short-term
stability of rotational tooth movement in dogs found that LLLT has no effect on the rate
of rotational movement. However, LLLT can significantly increase the short-term
stability of rotational movement with its effects decreasing over time[40].

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Figure IV: Low-level laser irradiation
Another study by Jahanbin et al., investigated the effectiveness of Er:YAG laser-aided
fiberotomy and low-level laser therapy in alleviating relapse of rotated incisors[41].
Patients were divided into four treatment groups (conventional CSF, Er:YAG laser-aided
CSF, LLLT, and control) and compared. Er:YAG laser-aided CSF proved to be an
effective alternative to conventional CSF in reducing rotational relapse. LLLT with
excessively high energy density was also as effective as the CSF procedures in alleviating
relapse, at least in the short term. Pocket depth changes and gingival recession are similar
in conventional and laser-aided supracrestal fiberotomy groups.

f. Expected changes over time

For over 30 years, Little and colleagues followed patients who had non-extraction
treatment with crowding, premolar extractions, incisor extractions, non-extraction
treatment with generalized spacing, and patients with no orthodontic treatment[43-49].
All of them showed similar changes in the dentition despite high variability in treatment.
The natural tendency after orthodontic retention is removed includes (1) a decrease in

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arch length and intercanine distance and (2) an increase in mandibular crowding (which
also occurs in untreated dentitions)[50]. Based on current evidence, it is impossible to
predict relapse on an individual basis, and there are no pretreatment variables that are
useful as predictors[49]. Additionally, third molars have little effect on relapse following
orthodontic treatment[44].

g. Records to assess rotational tooth movement

Tooth movement and outcomes of orthodontic treatment can be assessed by comparison
of photographs, cephalometric measurements and superimpositions, and
comparisons/measurements on dental casts. Photographs allow for qualitative assessment
of the dentition and are valuable in communicating with patients. However, due to the
likelihood of different camera angulation during photograph acquisition, it is not practical
to obtain quantitative information for precise assessment of change[51].

Cephalometric radiographs can be superimposed with great precision and accuracy to
assess changes in the dentition and jaws [52]. Their main disadvantage is that
cephalometric radiographs are two-dimensional (2D) representations of three-
dimensional (3D) structures. Overlapping of the left and right sides of the dentition
makes it difficult to obtain precise assessment of tooth movement.

Dental casts are the most frequently used 3D record in orthodontics and are regarded as
the most valuable orthodontic record[53]. However, casts cannot be superimposed in

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space and thus, changes in the dentition can only be made qualitatively by visual
inspection.

Digital photographs and digital radiographs are already in regular use, and the
introduction of digital models allows for the fully digitized patient record. Digital models
have several advantages over plaster models including: ease of data transmission, storage
over distance, superimposition, manipulation in all planes of space, digital caliper
measurements, and virtual model set-ups. Many studies have investigated whether digital
models are as accurate as their plaster counterparts.

Mayers et al. compared 48 pairs of plaster and digital pretreatment models using the PAR
index[54]. No significant differences were found between overall PAR scores indicating
that digital models could be used to make valid and reliable measures of occlusion. A
systematic review on the validity of the use of digital models to assess tooth size, arch
length, irregularity index, arch width, and crowding vs. measurements made on hand held
plaster models concluded that indirect measurements of digital models offer a high
degree of validity when compared to direct measurement on plaster models[55].

The AJODO investigated a step further by comparing the accuracy of measurements on
3D scanned models from plaster, 3D models from intraoral scans (Lava Chair side Oral
scanner), and plaster models[56]. Tooth widths were measured with a digital caliper on
plaster models and a virtual measurement tool on the digital models. Very few
measurements made on the digital models were different from those of the plaster models

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so it was determined that all three methods of model measurement were accurate and
reproducible.

Based on the current available research, it is reasonable to assume that digital models are
a valid and reliable record to measure malocclusion variables.

h. Targets of orthodontic treatment- Scoring systems

Several indices have been used to evaluate the outcome of orthodontic treatment by
comparing pretreatment and post-treatment records[57-60]. The Occlusal Index
evaluates treatment quality by looking at nine characteristics including: dental age, molar
relation, overbite, overjet, posterior cross-bite, posterior open-bite, tooth displacement
(actual and potential), midline relations, and missing permanent maxillary incisors.
However, this method has proved to be tedious and more appropriate for scoring pre-
rather than post-treatment records[61].

The Peer Assessment Rating Index (PAR) was developed to assess occlusion at any stage
of development[62]. There are 11 components of the PAR Index: upper right segment,
upper anterior segment, upper left segment, lower right segment, lower anterior segment,
lower left segment, right buccal occlusion, overjet, overbite, centerline, left buccal
occlusion. These characteristics are assigned individual scores, which are summed to
obtain the overall total that represents the degree a case deviates from normal alignment
and occlusion. The pre- and post-treatment scores are determined from the dental casts,

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and the difference between the two denotes the degree of improvement achieved by
orthodontic treatment. The PAR Index has good reliability and validity, but it is not
precise enough to discriminate between the minor inadequacies of tooth position.
The American Board of Orthodontics Objective Grading System (ABO OGS) was
developed as a precise method of objectively evaluating the quality of treatment by
looking at the post-treatment dental casts and panoramic radiograph[63]. The OGS
contains eight criteria: alignment, marginal ridges, buccolingual inclination, occlusal
relationships, occlusal contacts, overjet, interproximal contacts, and root angulation.
Proper alignment is a critical goal of orthodontic treatment because it has a heavy
influence on smile esthetics in the anterior region. Alignment is scored by evaluating the
incisal edges and lingual surfaces of the maxillary anterior teeth, and the incisal edges
and labio-incisal surfaces in the mandibular anterior region. In the posterior dentition, the
central grooves of the maxillary teeth are evaluated, and the buccal cusps of the
mandibular teeth are used to assess alignment. It has been shown that 80% of deductions
in ABO OGS scores are taken in the second molar and lateral incisor regions.
Marginal ridges are evaluated to ensure proper vertical positioning of the teeth. The
marginal ridges of adjacent teeth should be at the same level to allow for proper occlusal
contacts. Even marginal ridges allow the cemento-enamel junctions and bone heights to
also be level. Field tests indicate the majority of marginal ridge discrepancies occur
between the maxillary and mandibular first and second molars.

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To establish proper occlusion and eliminate balancing interferences during excursions,
buccolingual inclination of posterior teeth must be correct. In assessing the buccolingual
inclination, there should not be a significant difference between the heights of the buccal
and lingual cusps of the molars and premolars. Correct inclination of the maxillary and
mandibular second molars has proven the most difficult to obtain.
A major goal of orthodontic treatment is to establish maximum intercuspation of
opposing teeth. Occlusal contacts of the functioning cusps are used to assess the
adequacy of posterior occlusion. Again, maxillary and mandibular second molars are the
greatest problem area.
In order to assess the relative anteroposterior position of the posterior teeth, the occlusal
relationship is evaluated according to Angle’s classifications. The buccal cusps of the
maxillary molars, premolars, and canines should align within 1 mm of the interproximal
embrasure of the mandibular posterior teeth. The mesiobuccal cusp of the maxillary first
molar should align within 1 mm of the buccal groove of the mandibular first molar.
Overjet is important to evaluate the transverse relationship of the posterior dentition and
the anterior posterior relationship of the anterior teeth. In the posterior, mandibular buccal
cusps and maxillary lingual cusps should fit within the fossae of the opposing arch. In the
anterior region, mandibular incisors should contact the lingual surface of the maxillary
anterior teeth. Errors typically occur in the second molar and lower incisor regions.

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Interproximal contacts of adjacent teeth should be closed to provide the best post-
treatment esthetics and to prevent food impaction. This is typically an easy movement to
achieve but can be hard to maintain.
Root angulation is assessed on a panoramic radiograph to ensure maximum bone present
between adjacent teeth. Common mistakes in root angulation occur in the maxillary
lateral incisors, canines, second premolars, and mandibular first premolars.
In the ABO OGS, each of these characteristics is evaluated and points are deducted when
they deviate from ideal. In general, a case should lose no more than 30 points to be
considered quality treatment.
i. Assessment of rotational tooth movement- The literature
The inherent difficulty in accurately measuring the pre- and post-treatment rotational
changes of teeth has been well documented in the literature [64, 65]. Therefore, Little’s
“Irregularity Index” is often employed to assess the degree of dental malrelationships at
different time points. This technique involves measuring the linear distance from
anatomic contact point to adjacent anatomic contact point of the mandibular anterior teeth
(Figure V). The sum of the five measurements represents the degree of anterior
irregularity and is noted as the Irregularity Index[66]. Perfect alignment would
theoretically have a score of 0, and a higher index score would represent increased
crowding. Little’s Irregularity index can be used to measure relapse by comparing the
scores from models obtained on the day of appliance removal to scores from models
obtained 2 to 3 years post-retention as was done in a study by Edwards[42]. The

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disadvantage of using Little’s Irregularity Index to assess rotational relapse is that the
score does not isolate rotational changes in the alignment and it can only be used to study
the anterior teeth.

Figure V: Little’s Irregularity Index is represented by the sum of the distances
A+B+C+D+E.
Another study by Swanson et al. measured rotational relapse by studying the angle of
teeth relative to the midpalatal raphe[65]. The study sample was comprised of initial, end
of treatment, and post-retention dental casts from 116 cases treated at the University of
Washington Graduate Orthodontic Clinic and from the private practice of Dr. R. A.
Riedel. On the casts from each time point, the cusp tip, cingulum, midincisal and
midpalatal raphe points were marked (Figure VI). A point on the midpalatal raphe
between the most anterior rugae was selected as well as between the most posterior
rugae. The midpalatal plane was transferred to the mandibular casts with a
symmetriscope. The coordinates of these selected points were digitized, and computer
techniques were employed to assess the rotational position of each tooth by constructing

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a straight line through the proper points and measuring its angular relationship to the
midpalatal raphe as seen in Figure VI. The measurements from the initial, end of
treatment, and post-retention casts were compared to see changes in individual tooth
angulations and an indication of rotational movements. Findings of this study indicated
that age, sex, classification, presence of extractions, and growth of the maxilla or
mandible had no effect on rotations found at the end of the post-retention period.
However, the amount a tooth is orthodontically rotated may affect the amount of
rotational relapse in the same tooth during the post-retention period. This study
demonstrated that the cuspids are the most frequently rotated teeth in the pre-treatment an
post-retention periods.

Figure VI: Method of angular measurements on mandibular cast.

Study Objective

The mechanics of rotating malposed teeth into the arch is rarely a problem in
orthodontics. However, it is well known that rotational relapse is possibly the most

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common post-orthodontic movement, and the hardest to prevent. The aim of this study is
to evaluate the prevalence of rotational relapse and investigate any directional patterns in
order to improve relapse prevention protocols.

IV. Materials and Methods

Maxillary and Mandibular dental models were compared at three time points, initial
malocclusion (T1), day of appliance removal (T2), and 6-16 days later at retainer delivery
(T3), and evaluated to observe rotational relapse patterns. The study sample consisted of
orthodontic records of 13 consecutively de-bonded patients from the University of
Southern California graduate orthodontic clinic. Eight female and five male patients
participated, and were in the age range of 9-38 at the time of appliance removal (Table I).
Participants included in the study were full maxillary and mandibular orthodontic cases
that were consecutively de-bonded between August 27
th
2013 and October 15
th
2013.
Partial orthodontic cases and cases where full records could not be located were
excluded.
Age range Male Female Total
9-16 1 4 5
17-21 2 4 6
21-38 2 0 2
n= 5 n=8 n=13
Table I: Age and gender of study sample at time of appliance removal

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At each time point, intraoral photos and alginate impressions were taken. Impressions
were poured within 10 minutes into orthodontic white stone and plaster models were
roughly trimmed to remove excess stone and all positive bubbles on the dentition. The
models from T2 and T3 were scanned using the Ortho Insight 3D Desktop Scanner
(Motionview software LLC; Tennessee). Maxillary and mandibular arches were scanned
individually by placing them in the laser scanner one at a time with anterior teeth facing
out and occlusal surfaces facing up. Scanned models were saved as a randomized number
to keep the anonymity of patients and eliminate any possible bias, and were exported to
the Geomagic Studio 2012 Version 10 (Morrisville, NC) software system for
superimposition. For each patient, maxillary and mandibular models were imported into
Geomagic simultaneously. The lasso tool was used to select and remove any portion of
the model not needed for registration, including the gingival tissues, to leave just a 3D
model of the dentition. Once properly trimmed, the cropped models were saved as .stl
files in the same anonymous format.

An n-point registration was used to register the T2 and T3 3D models of each arch. The
T2 models were used as the “reference” and remained stable while the T3 “test” models
were superimposed. Nine homologous points were chosen on the teeth of T2 and T3
models to allow for a procrustes type registration. If a point was chosen on one side of the
arch, a similar point was also selected on the contralateral side of the arch, and the same
points were chosen at each subsequent time point. Once 9 homologous points were
chosen, an n-point superimposition based on minimizing the distance between the points
was completed by the Geomagic software. Following the n-point superimposition, a

25

global “best fit” registration was performed based on surface-to-surface registration of
the T2 and T3 digital models. Using the “best fit” registration, it was possible to visualize
the direction of the rotational relapse that occurred between appliance removal and
retainer delivery.

To verify the reproducibility of the 3D model superimposition, 3 maxillary and 3
mandibular models from T2 were n-point and globally registered with the corresponding
models from T3 two independent times. After models were properly registered, the
models from T3 from the two independent superimpositions were saved as “Version 1”
and “Version 2”. These models should theoretically be positioned identically in space as
long as the Geomagic repeated registration system does not introduce any positional
variability into the system. Comparison of “Version 1” and “Version 2” by color mapping
showed no variability and verified the reproducibility of the superimposition protocol.

Models from T1 and T2 could not be registered in a valid and precise manner because
stable reference landmarks or structures could not be defined between the two time
points. Thus, the stone models were visually assessed from an occlusal perspective to
determine how the teeth were rotated from their initial position to the corrected position.
Each tooth was looked at individually and it was determined whether the teeth were
rotated mesially or distally by looking at the alignment of the buccal cusps and central
grooves for posterior teeth, and the incisal edges for anterior teeth. The superimposed
digital models from T2 and T3 allowed qualitative analysis of individual tooth
movements that occurred between appliance removal and retainer delivery. The 3D color

26

maps were used to note whether each tooth rotated mesially, distally, or did not relapse
after appliance removal. Rotational movements from T1 to T2 were compared to
movements between T2 and T3 to observe whether each tooth: (1) relapsed in the same
direction as orthodontic movement, (2) relapsed in the opposite direction as orthodontic
movement, (3) did not relapse, (4) relapsed after no orthodontic rotation, (5) was not
rotated orthodontically and did not relapse.

All statistical analysis was done with Microsoft Excel. A chi square test (P<0.05)
determined if the teeth that were moved orthodontically were more likely to relapse than
teeth that were not moved during treatment.

V. Results
For each patient, a superimposition of the digital models from T2 and T3 was generated
for the maxillary and mandibular arches. Figure VII shows the maxillary superimposition
of one patient involved in this study. The 3D color map shows that the upper centrals
rotated lingually at the mesial between T2 and T3. The upper right lateral and cuspid also
rotated lingually at the mesial after debond.

Figure VII: Maxillary T2 and T3 superimposition

27

Rotational movements for each tooth were determined from the 3D color maps and the
data was charted on an individual patient basis (Figure VIII).

Figure VIII: Single patient rotation chart T2 to T3

For each patient, the data gathered from T1 to T2 based on visual analysis of the stone
models was charted in the same manner (Figure IX).

Figure IX: Single patient rotation chart T1 to T2

28

With movements documented for each tooth, rotational charts with data from T1 to T2
could be compared to charts with data from T2 to T3 for each patient in order to
determine the direction of rotational relapse. Table II summarizes the number of teeth
that relapsed in the same direction as orthodontic movement, relapsed in the opposite
direction as orthodontic movement, did not relapse, relapsed after no orthodontic rotation,
or were not rotated orthodontically and did not relapse for each patient. Tables III-V
summarize this data for three different age groups: 9-16, 17-21, and 22-28.

Patient Same
Direction
Opposite
Direction
No
Relapse
Relapse
after no
orthodontic
rotation
No ortho
and no
relapse
Total
1001 0 1 8 1 10 20
1002 0 0 12 0 12 24
1003 0 5 8 0 7 20
1004 0 1 16 0 7 24
1005 1 0 10 0 13 24
1006 0 3 16 0 5 24
1007 0 2 4 4 14 24
1008 0 0 12 4 8 24
1009 1 4 13 0 6 24
1010 1 3 16 0 0 20
1011 0 4 8 0 12 24
1012 0 4 14 1 3 22
1013 0 0 14 2 8 24
n= 3 27 151 12 105 298
Frequency
(n/Total)
0.01 0.09 0.51 0.04 0.35
Table II. Number of teeth and direction of rotation after appliance removal by patient.

29

Patient Same
Direction
Opposite
Direction
No
Relapse
Relapse
after no
orthodontic
rotation
No ortho
and no
relapse
Total
1004 0 1 16 0 7 24
1007 0 2 4 4 14 24
1008 0 0 12 4 8 24
1009 1 4 13 0 6 24
1013 0 0 14 2 8 24
n= 1 7 59 10 43 120
Frequency
(n/Total)
0.01 0.06 0.50 0.08 0.36
Table III: Number of teeth and direction of rotation after appliance removal by patient in
the 9-16 age range.

Patient Same
Direction
Opposite
Direction
No
Relapse
Relapse
after no
orthodontic
rotation
No ortho
and no
relapse
Total
1001 0 1 8 1 10 20
1002 0 0 12 0 12 24
1003 0 5 8 0 7 20
1006 0 3 16 0 5 24
1010 1 3 16 0 0 20
1012 0 4 14 1 3 22
n= 1 16 74 2 37 130
Frequency
(n/Total)
0.01 0.12 0.57 0.02 0.28
Table IV: Number of teeth and direction of rotation after appliance removal by patient in
the 17-21 age range.

Patient Same
Direction
Opposite
Direction
No
Relapse
Relapse
after no
orthodontic
rotation
No ortho
and no
relapse
Total
1005 1 0 10 0 13 24
1011 0 4 8 0 12 24
n= 1 4 18 0 25 48
Frequency
(n/Total)
0.02 0.08 0.38 0 0.52
Table V: Number of teeth and direction of rotation after appliance removal by patient in
the 22-38 age range.

30

In addition, each tooth was looked at individually to observe whether it relapsed in the
same direction as orthodontic movement, relapsed in the opposite direction as orthodontic
movement, did not relapse, relapsed after no orthodontic rotation, or was not rotated
orthodontically and did not relapse, and the results were charted in Table VI.

Lowe
r
Centr
als
Low
er
Late
rals
Low
er
Cusp
ids
Lower
First
Bicusp
ids
Lower
Secon
d
Bicusp
ids
Low
er
Mol
ars
Uppe
r
Centr
als
Upp
er
Late
rls
Uppe
r
Cusp
ids
Upper
First
Bicusp
ids
Upper
Secon
d
Bicusp
ids
Upp
er
First
Mol
ars
Total
Same
direction
0 0 0 1 0 0 0 1 1 0 0

0 3
Opposite
direction
3 0 4 1 1 0 4 5 7 0 2 0 27
No
relapse
10 15 16 6 18 8 19 18 6 9 13 13 151
Relapse
after no
rotation
1 0 0 1 1 0 2 0 1 2 4 0 12
No ortho
and no
relapse
12 9 6 11 6 18 1 2 11 9 7 13 105
n=
26 24 26 20 26 26 26 26 26 20 26 26 298
Table VI. Number of teeth and direction of rotation after appliance removal by tooth
type

Overall among the teeth that were moved orthodontically, most had no rotational relapse
(n=151, 50.7%), followed by relapse in the opposite direction (n=27, 9.1%) and relapse
in the same direction (n=3, 1.0%) of orthodontic movement. The data suggests that teeth
are nine times more likely to relapse in the opposite direction of orthodontic rotation than
in the same direction. A large proportion of the teeth sampled were not moved
orthodontically and did not relapse after appliance removal (n=105, 35.2%). Surprisingly,
a small proportion of teeth relapsed even when not moved orthodontically from T1 to T2
(n=12, 4.0%).

31

The lower first bicuspids, upper laterals, and upper cuspids were the only teeth to relapse
in the same direction as orthodontic movement. Among the teeth that relapsed in the
opposite direction, the upper bicuspids relapsed most (n=7, 2.3%), followed by the upper
laterals (n=5, 1.7%), upper centrals (n=4, 1.3%), and lower cuspids (n=4, 1.3%). Relapse
after no orthodontic rotation occurred most frequently in the upper second bicuspids
(n=4, 1.3%).

Figure X: Number of teeth and direction of rotation after appliance removal.

When analyzing if the teeth that were moved orthodontically were more likely to relapse
than teeth that were not moved during treatment, no significant difference was found (P=
0.13). Of the teeth that were moved orthodontically, 16.6% experienced rotational
relapse. This can be compared to the 10.2% of teeth that relapsed that were not initially
moved through orthodontic treatment. When a chi square test was run, the expected
probability of relapse was compared to the observed values (Table VII-VIII). The
0

20

40

60

80

100

120

140

160

SAME
OPPOSITE
NO
RELAPSE
RELAPSE
NO

ORTHO

NO
ORTHO

NO
RELAPSE

Number
of
Teeth

Direction
of
Relapse

32

expected probability of relapse after orthodontic movement was calculated by
multiplying the total number of teeth that relapsed by the total number of teeth that were
moved orthodontically and dividing by the grand total of all teeth studied. The remaining
expected values were calculated in the same manner. The comparison of expected and
observed values produced a P value of 0.13, indicating that rotational relapse is just as
likely to occur in unmoved teeth as it is in orthodontically rotated teeth.

Observed
Relapse No Relapse Total
Ortho 30 151 181
No Ortho 12 105 117
Total 42 256 298
Table VII: Observed presence or absence of relapse in orthodontically rotated and not
rotated teeth.

Expected
Relapse No Relapse Total
Ortho 26 155 181
No Ortho 16 101 117
Total 42 256 298
Table VIII: Expected presence or absence of relapse in orthodontically rotated and not
rotated teeth.

33

VI. Discussion

While many studies have investigated post-orthodontic tooth relapse, our study appears to
be the first study related to directionality of rotational relapse of individual teeth. In this
study, models from 13 consecutively de-bonded patients form the University of Southern
California graduate orthodontic clinic were assessed at their initial malocclusion (T1),
day of appliance removal (T2), and 6-16 days later at retainer delivery (T3). Rotational
movements from T1to T2 were compared to movements between T2 and T3 to observe
whether each tooth: (1) relapsed in the same direction as orthodontic movement, (2)
relapsed in the opposite direction as orthodontic movement, (3) did not relapse, (4)
relapsed after no orthodontic rotation, (5) were not rotated orthodontically and did not
relapse.

Findings of this study suggest that the majority of teeth that are moved orthodontically do
not relapse between appliance removal and retainer delivery. A study by Lyotard et al
evaluated short-term post-orthodontic changes in the absence of retention for thirty
participating patients[67]. At the end of active treatment, archwires were removed, and
alginate impressions were taken. A second set of impressions were taken four weeks
later, and used for comparison to the initial using the American Board of Orthodontics’
Objective Grading System. After four weeks without archwires or other retention, 13 of
the 30 patients required no additional orthodontic treatment. This study supports our
conclusions that some teeth will be intrinsically stable after removal of orthodontic
appliances.

34

The results of this study suggest that a larger percentage of teeth will relapse in the
opposite direction of initial orthodontic movement than in the same direction, indicating
that teeth tend to relapse back to their pretreatment dental positions. Additionally, certain
teeth tend to undergo more rotational relapse than others. The upper bicuspids relapsed in
the opposite direction of orthodontic movement most, followed by the upper laterals,
upper centrals, and lower cuspids. This can be compared to Edward’s findings that
determined lower cuspids relapse most, followed by upper cuspids, lower second
bicuspids, and lower first molars[42]. Rotational relapse may be due to the use of elastics,
which are typically attached to the hook of the cuspid bracket towards the end of
treatment. Tooth anatomy may contribute to mandibular cuspid distal rotation due to the
greater convexity seen at the mesial of these teeth. In the current study, the finding that
none of the molars experienced any type of rotational relapse may be due to their large
root surface area. With the double root structure of the mandibular molars and triple root
structure of the maxillary molars, rotational relapse is less likely to occur.

The tendency of certain teeth to relapse more than others is likely influenced by the
amount of rotational correction required from the initial dental position. Wiser and
Swanson both separately reported a direct relationship between relapse and initial
rotation[65, 68]. Ultimately, teeth that require a greater amount of rotational correction
are more likely to relapse and should be considered for surgical intervention.

Periodontal fibers have been cited in the literature as playing a predominant roll in the
relapse of orthodontically rotated teeth. Several techniques for prevention of relapse

35

have been suggested including early treatment, surgical interruption of the supra-alveolar
fibers, and long-term retention.

Edward’s study of the circumferential supracrestal fiberotomy procedure indicated that it
is an effective therapy for preventing rotational relapse[42]. Other studies by Jahanbin et
al. have shown Er:YAG laser-aided CSF and LLLT to be effective, less invasive
alternatives to conventional CSF[41]. These findings suggest that surgical interventions
may be an important therapy for relapse prevention. The current study, however, did not
involve any patients who were subject to these procedures, so direct evaluation cannot be
made.

Reitan suggested that rotated teeth are less likely to relapse if corrected early[8, 11].
Rotations should be addressed early in orthodontic treatment to allow more time for
periodontal tissues to remodel. A comparison of the response of bone tissue in children
and adults found that adult tissues have fewer cellular elements and stronger, thicker fiber
bundles[10]. This static state accounts for the slower response of adult tissues to
orthodontic forces and may contribute to greater relapse due to slower remodeling of
tissues. In children, supporting tissues contain a greater amount of cellular elements and
are in a stage of proliferation during orthodontic movement. Tissues respond quicker to
forces and the new fibers formed during movement naturally enhance maintenance of the
new tooth position. Thus, rotational movements may be more stable when corrected in
children rather than adults. The sample population in the current study, however,
experienced relapse at a similar frequency regardless of age.

36

A small proportion of teeth relapsed even when not moved orthodontically. This finding
may be a result of normal maturation and decrease in arch perimeter, including maxillary
and mandibular compensations and post-treatment active growth. Van der Linden
described the crowding that develops in the middle or late teens as tertiary crowding[69].
Because most patients are treated in their adolescence, there is a high probability of
subsequent growth of the maxillary and mandibular complexes that may alter the
established tooth alignment[70, 71]. With continued post-orthodontic growth of the
mandible that continues after maxillary growth ceases, lingually directed forces from the
maxillary arch and labial soft tissues can cause uprighting of the mandibular incisors.
This uprighting can result in crowding by forcing the incisors to occupy a smaller arch
perimeter[7]. Perera reported a relationship between mandibular growth and mandibular
anterior crowding in untreated subjects, implicating this growth as a cause of the
crowding that commonly occurs after adolescence[72]. It is clear that this differential
mandibular growth and tertiary crowding is not uncommon, occurring in treated as well
as untreated patients, and may be the cause of relapse in teeth that were not moved
orthodontically to begin with.

Lundstrom evaluated untreated subjects for changes in the dimensions of the dental
arches [73]. The arch width and arch length were measured from 41 subjects in the early
permanent dentition and again 14 years later. The study found that arch length was
reduced by an average of 1 to 2 mm accompanied by an increase in crowding. Arch
width did not change in this sample.

37

Richardson and Gormley reported similar results in a study of 20 untreated men and 26
untreated women in the adult dentition[74]. Mandibular study casts were collected at
ages 18 (T1), 21 (T2), and 28 (T3), and incisor crowding, intercanine width, intermolar
width, and arch length were measured at all 3 time points. There was a statistically
significant mean increase in crowding and decrease in arch length from T1 to T2.
Changes from T2 to T3 were similar but to a greater extent. Again, no changes were seen
in arch widths.

In another study of untreated subjects, Sinclair and Little found that arch length decreased
and incisor irregularity increased from the mixed dentition into early adulthood[75].
Changes in mandibular arch length, mandibular intercanine width, overbite, and overjet
were not associated with mandibular crowding at 13 years old as measured by the change
in incisor irregularity. Because no clinically significant variables were predictive of
mandibular incisor crowding, they concluded that the changes were due to normal
maturational processes.

While orthodontic patients often exhibit decreases in arch length and tooth alignment
over time, these studies show that this trend can also be seen in the dental arches of
untreated patients. Along with active post-orthodontic growth, inevitable decreases in
arch length may explain why some of the teeth in our study sample relapsed even though
they were not rotated orthodontically.

38

Post-orthodontic tooth movement is often regarded as an unwanted result of appliance
removal; however, some degree of settling can be beneficial to patient occlusion. A study
by Nett and Huang evaluated one hundred randomly chosen subjects from the post-
retention archives of the Department of Orthodontics at the University of Washington.
Pre-treatment PAR scores and post-treatment and post-retention ABO OGS scores were
measured on study casts to asses alignment, marginal ridges, buccolingual inclinations,
occlusal contacts, occlusal relationships, and overjet. It was determined that the mean
overall OGS score improved by approximately 4 points from post-treatment to post-
retention, indicating an improvement in most of the criteria studied. Alignment was the
only criteria associated with a mean long-term worsening and a less predictable pattern of
change. Thus, while some degree of settling is desired, alignment can be expected to
worsen if teeth are not retained properly. It has been shown that Hawley’s allow a greater
degree of settling than VFRs [15]. Therefore if maintenance of the alignment is of utmost
importance, VFRs should be considered as the primary means of retention.

As with any pilot study, there were a few limitations. A larger sample of patients needs to
be studied. Because the study sample differed in initial malocclusion, treatment plan, and
treatment mechanics, the groups could be broken down and studied individually to
discover how these differences may influence rotational relapse. Relapse is a continuous
process that may continue beyond retainer delivery, so patients could be evaluated at
longer intervals after appliance removal. In obtaining patient records, the accuracy of the
initial alginate impressions is not as precise as some of the other commercially available
dental products such as Polyvinyl siloxane (PVS). While analysis of models in 3D has

39

been shown to be a valid qualitative measurement technique for model superimposition,
the accuracy of the superimpositions is limited by the presence of stable registration
surfaces. Models from T1 and T2 could not be superimposed digitally, so evaluation of
individual tooth movements could only be made visually and qualitatively, and the
amount of rotational movements could not be quantitatively compared. Data collected by
visual assessment of the patient models may be subjective and should be reproduced by
the same or additional researchers to validate the results.

In addition to evaluating patients at longer intervals after appliance removal to further
investigate rotational relapse patterns, future studies could use the same protocol to
analyze different relapse movements. The data collected in this study could be used to
evaluate any patterns in the relapse of tip as indicated by the superimpositions and 3D
color maps.

VII. Conclusions
1. The majority of teeth that are moved orthodontically do not relapse between
appliance removal and retainer delivery.
2. Of the teeth that relapse, a larger percentage will relapse in the opposite direction
of initial orthodontic movement than in the same direction.
3. The upper bicuspids relapsed in the opposite direction of orthodontic movement
most, followed by the upper laterals, upper centrals, and lower cuspids.
4. Molars experienced absolutely no rotational relapse.

40

5. The tendency of certain teeth to relapse more than others is influenced by the
amount of rotational correction required from the initial dental position.
6. Rotational relapse occurs less in children rather than adults.
7. Teeth may relapse even when not moved orthodontically due to normal
maturation and decrease in arch perimeter.
8. Rotational relapse is just as likely to occur in unmoved teeth as it is in
orthodontically rotated teeth.

41

VIII. References
1.
Dyer,
K.C.,
J.L.
Vaden,
and
E.F.
Harris,
Relapse
revisited—again.
American

Journal
of
Orthodontics
and
Dentofacial
Orthopedics,
2012.
142(2):
p.
221-‐
227.

2.
Erdinc,
A.E.,
R.S.
Nanda,
and
E.
Işıksal,
Relapse
of
anterior
crowding
in
patients

treated
with
extraction
and
nonextraction
of
premolars.
American
Journal
of

Orthodontics
and
Dentofacial
Orthopedics,
2006.
129(6):
p.
775-‐784.

3.
Francisconi,
M.F.,
et
al.,
Overjet,
overbite,
and
anterior
crowding
relapses
in

extraction
and
nonextraction
patients,
and
their
correlations.
American

Journal
of
Orthodontics
and
Dentofacial
Orthopedics,
2014.
146(1):
p.
67-‐72.

4.
Sharpe,
W.,
et
al.,
Orthodontic
relapse,
apical
root
resorption,
and
crestal

alveolar
bone
levels.
American
Journal
of
Orthodontics
and
Dentofacial

Orthopedics,
1987.
91(3):
p.
252-‐258.

5.
Shields,
T.E.,
R.M.
Little,
and
M.K.
Chapko,
Stability
and
relapse
of
mandibular

anterior
alignment:
A
cephalometric
appraisal
of
first-‐premolar-‐extraction

cases
treated
by
traditional
edgewise
orthodontics.
American
Journal
of

Orthodontics,
1985.
87(1):
p.
27-‐38.

6.
Edwards,
J.G.,
A
study
of
the
periodontium
during
orthodontic
rotation
of
teeth.

American
Journal
of
Orthodontics,
1968.
54(6):
p.
441-‐461.

7.
W.,
P.,
Contemporary
Orthodontics.
2007,
St.
Luis,
MO:
Mosby
Elsevier.

8.
Reitan,
K.,
Principles
of
retention
and
avoidance
of
posttreatment
relapse.

American
Journal
of
Orthodontics,
1969.
55(6):
p.
776-‐790.

9.
Ahrens,
D.G.,
Y.
Shapira,
and
M.M.
Kuftinec,
An
approach
to
rotational
relapse.

American
Journal
of
Orthodontics,
1981.
80(1):
p.
83-‐91.

10.
Reitan,
K.,
Clinical
and
histologic
observations
on
tooth
movement
during
and

after
orthodontic
treatment.
American
Journal
of
Orthodontics,
1967.
53(10):

p.
721-‐745.

11.
Reitan,
K.,
Tissue
behavior
during
orthodontic
tooth
movement.
American

Journal
of
Orthodontics,
1960.
46(12):
p.
881-‐900.

12.
Jacobson,
A.,
Biological
mechanisms
of
tooth
movement.
American
Journal
of

Orthodontics
and
Dentofacial
Orthopedics,
2009.
136(1):
p.
139.

13.
Thilander,
B.,
Orthodontic
relapse
versus
natural
development.
American

Journal
of
Orthodontics
and
Dentofacial
Orthopedics,
2000.
117(5):
p.
562-‐
563.

14.
Krishnan,
V.
and
Z.e.
Davidovitch,
Cellular,
molecular,
and
tissue-‐level

reactions
to
orthodontic
force.
American
Journal
of
Orthodontics
and

Dentofacial
Orthopedics,
2006.
129(4):
p.
469.e1-‐469.e32.

15.
Littlewood,
S.J.,
et
al.,
Retention
procedures
for
stabilising
tooth
position
after

treatment
with
orthodontic
braces.
Cochrane
Database
Syst
Rev,
2006(1):
p.

Cd002283.

16.
Richard,
A.R.,
A
Review
Of
The
Retention
Problem.
The
Angle
Orthodontist,

1960.
30(4):
p.
179-‐199.

42

17.
LR.,
B.,
Fiberotomy
and
reproximation
without
lower
retention
9
years
in

retrospect:
part
II.
Angle
Orthod,
1980(50):
p.
169-‐78.

18.
Jarjoura,
K.,
G.
Gagnon,
and
L.
Nieberg,
Caries
risk
after
interproximal
enamel

reduction.
American
Journal
of
Orthodontics
and
Dentofacial
Orthopedics,

2006.
130(1):
p.
26-‐30.

19.
Zachrisson,
B.U.,
L.
Nyøygaard,
and
K.
Mobarak,
Dental
health
assessed
more

than
10
years
after
interproximal
enamel
reduction
of
mandibular
anterior

teeth.
American
Journal
of
Orthodontics
and
Dentofacial
Orthopedics,
2007.

131(2):
p.
162-‐169.

20.
Prakash
A,
R.S.,
Arya
G,
Jain
S,
Nilachandra,
Fixed
Retention-‐
A
Review.
The

Orthodontic
Cyberjournal,
2013.

21.
Moffitt,
A.H.
and
J.
Raina,
Long-‐term
bonded
retention
after
closure
of

maxillary
midline
diastema.
American
Journal
of
Orthodontics
and

Dentofacial
Orthopedics,
2015.
148(2):
p.
238-‐244.

22.
RT,
L.,
The
lower
incisor
bonded
retainer
in
clinical
practice:
a
three
year
study.

Br
J
Orthod,
1981(8):
p.
15-‐18.

23.
Zachrisson,
B.U.,
The
bonded
lingual
retainer
and
multiple
spacing
of
anterior

teeth.
Swed
Dent
J
Suppl,
1982.
15:
p.
247-‐55.

24.
Colin
Melrose,
B.,
FDS,
MSc,
MOrth,a
and
Declan
T.
Millett,
BDSc,
FDS,
DDS,

MOrth,
Toward
a
perspective
on
orthodontic
retention?
Am
J
Orthod

Dentofacial
Orthop
1998(113):
p.
507-‐14.

25.
Rowland,
H.,
et
al.,
The
effectiveness
of
Hawley
and
vacuum-‐formed
retainers:

A
single-‐center
randomized
controlled
trial.
American
Journal
of
Orthodontics

and
Dentofacial
Orthopedics,
2007.
132(6):
p.
730-‐737.

26.
Demir,
A.,
et
al.,
Comparison
of
retention
characteristics
of
Essix
and
Hawley

retainers.
Korean
Journal
of
Orthodontics,
2012.
42(5):
p.
255-‐262.

27.
Barlin,
S.,
et
al.,
A
retrospective
randomized
double-‐blind
comparison
study
of

the
effectiveness
of
Hawley
vs
vacuum-‐formed
retainers.
The
Angle

Orthodontist,
2011.
81(3):
p.
404-‐409.

28.
Zachrisson,
B.U.,
Long-‐term
experience
with
direct-‐bonded
retainers:
update

and
clinical
advice.
J
Clin
Orthod,
2007.
41(12):
p.
728-‐37;
quiz
749.

29.
Pratt,
M.C.,
G.T.
Kluemper,
and
A.F.
Lindstrom,
Patient
compliance
with

orthodontic
retainers
in
the
postretention
phase.
American
Journal
of

Orthodontics
and
Dentofacial
Orthopedics,
2011.
140(2):
p.
196-‐201.

30.
Artun,
J.,
A.T.
Spadafora,
and
P.A.
Shapiro,
A
3-‐year
follow-‐up
study
of
various

types
of
orthodontic
canine-‐to-‐canine
retainers.
Eur
J
Orthod,
1997.
19(5):
p.

501-‐9.

31.
Stormann,
I.
and
U.
Ehmer,
A
prospective
randomized
study
of
different

retainer
types.
J
Orofac
Orthop,
2002.
63(1):
p.
42-‐50.

32.
Renkema,
A.-‐M.,
et
al.,
Effectiveness
of
lingual
retainers
bonded
to
the
canines

in
preventing
mandibular
incisor
relapse.
American
Journal
of
Orthodontics

and
Dentofacial
Orthopedics,
2008.
134(2):
p.
179.e1-‐179.e8.

33.
Booth,
F.A.,
J.M.
Edelman,
and
W.R.
Proffit,
Twenty-‐year
follow-‐up
of
patients

with
permanently
bonded
mandibular
canine-‐to-‐canine
retainers.
American

Journal
of
Orthodontics
and
Dentofacial
Orthopedics,
2008.
133(1):
p.
70-‐76.

43

34.
Årtun,
J.,
Caries
and
periodontal
reactions
associated
with
long-‐term
use
of

different
types
of
bonded
lingual
retainers.
American
Journal
of
Orthodontics,

1984.
86(2):
p.
112-‐118.

35.
Pandis,
N.,
et
al.,
Long-‐term
periodontal
status
of
patients
with
mandibular

lingual
fixed
retention.
The
European
Journal
of
Orthodontics,
2007.
29(5):
p.

471-‐476.

36.
Scheibe
K,
R.S.,
Lower
bonded
retainers:
survival
and
failure
rates
particularly

considering
operator
experience.
J
Orofac
Orthop,
2010(71):
p.
300-‐7.

37.
Pratt,
M.C.,
et
al.,
Evaluation
of
retention
protocols
among
members
of
the

American
Association
of
Orthodontists
in
the
United
States.
American
Journal

of
Orthodontics
and
Dentofacial
Orthopedics,
2011.
140(4):
p.
520-‐526.

38.
Keim,
R.G.,
et
al.,
2002
JCO
study
of
orthodontic
diagnosis
and
treatment

procedures.
Part
1.
Results
and
trends.
J
Clin
Orthod,
2002.
36(10):
p.
553-‐68.

39.
Littlewood,
S.J.,
et
al.,
Orthodontic
retention:
A
systematic
review.
Journal
of

Orthodontics,
2006.
33(3):
p.
205-‐212.

40.
Salehi,
P.,
et
al.,
Effect
of
low-‐level
laser
irradiation
on
the
rate
and
short-‐term

stability
of
rotational
tooth
movement
in
dogs.
American
Journal
of

Orthodontics
and
Dentofacial
Orthopedics,
2015.
147(5):
p.
578-‐586.

41.
Jahanbin,
A.,
et
al.,
Effectiveness
of
Er:YAG
laser-‐aided
fiberotomy
and
low-‐level

laser
therapy
in
alleviating
relapse
of
rotated
incisors.
American
Journal
of

Orthodontics
and
Dentofacial
Orthopedics,
2014.
146(5):
p.
565-‐572.

42.
Edwards,
J.G.,
A
long-‐term
prospective
evaluation
of
the
circumferential

supracrestal
fiberotomy
in
alleviating
orthodontic
relapse.
American
Journal
of

Orthodontics
and
Dentofacial
Orthopedics,
1988.
93(5):
p.
380-‐387.

43.
Little,
R.M.,
Stability
and
relapse
of
mandibular
anterior
alignment:
University

of
Washington
studies.
Semin
Orthod,
1999.
5(3):
p.
191-‐204.

44.
Little,
R.M.,
Clinical
implications
of
the
University
of
Washington
post-‐retention

studies.
J
Clin
Orthod,
2009.
43(10):
p.
645-‐51.

45.
Little,
R.M.,
Dr.
Robert
M.
Little
on
the
University
of
Washington
post-‐retention

studies.
J
Clin
Orthod,
2009.
43(11):
p.
723-‐7.

46.
Little,
R.M.
and
R.A.
Riedel,
Postretention
evaluation
of
stability
and
relapse—
Mandibular
arches
with
generalized
spacing.
American
Journal
of

Orthodontics
and
Dentofacial
Orthopedics,
1989.
95(1):
p.
37-‐41.

47.
Little,
R.M.,
R.A.
Riedel,
and
J.
Artun,
An
evaluation
of
changes
in
mandibular

anterior
alignment
from
10
to
20
years
postretention.
American
Journal
of

Orthodontics
and
Dentofacial
Orthopedics,
1988.
93(5):
p.
423-‐428.

48.
Little,
R.M.,
T.R.
Wallen,
and
R.A.
Riedel,
Stability
and
relapse
of
mandibular

anterior
alignment—first
premolar
extraction
cases
treated
by
traditional

edgewise
orthodontics.
American
Journal
of
Orthodontics,
1981.
80(4):
p.

349-‐365.

49.
RM.,
L.,
Stability
and
relapse
of
dental
arch
alignment.
Br
J
Orthod,
1990(17):

p.
235-‐41.

50.
Shah,
A.A.,
Postretention
changes
in
mandibular
crowding:
a
review
of
the

literature.
American
Journal
of
Orthodontics
and
Dentofacial
Orthopedics,

2003.
124(3):
p.
298-‐308.

44

51.
Sandler,
J.,
et
al.,
Quality
of
clinical
photographs
taken
by
orthodontists,

professional
photographers,
and
orthodontic
auxiliaries.
American
Journal
of

Orthodontics
and
Dentofacial
Orthopedics,
2009.
135(5):
p.
657-‐662.

52.
Björk,
A.,
Prediction
of
mandibular
growth
rotation.
American
Journal
of

Orthodontics,
1969.
55(6):
p.
585-‐599.

53.
Han,
U.K.,
et
al.,
Consistency
of
orthodontic
treatment
decisions
relative
to

diagnostic
records.
American
Journal
of
Orthodontics
and
Dentofacial

Orthopedics,
1991.
100(3):
p.
212-‐219.

54.
Mayers,
M.,
et
al.,
Comparison
of
peer
assessment
rating
(PAR)
index
scores
of

plaster
and
computer-‐based
digital
models.
American
Journal
of
Orthodontics

and
Dentofacial
Orthopedics,
2005.
128(4):
p.
431-‐434.

55.
Fleming,
P.S.,
V.
Marinho,
and
A.
Johal,
Orthodontic
measurements
on
digital

study
models
compared
with
plaster
models:
a
systematic
review.
Orthodontics

&
Craniofacial
Research,
2011.
14(1):
p.
1-‐16.

56.
Wiranto,
M.G.,
et
al.,
Validity,
reliability,
and
reproducibility
of
linear

measurements
on
digital
models
obtained
from
intraoral
and
cone-‐beam

computed
tomography
scans
of
alginate
impressions.
American
Journal
of

Orthodontics
and
Dentofacial
Orthopedics,
2013.
143(1):
p.
140-‐147.

57.
Eismann,
D.,
Reliable
assessment
of
morphological
changes
resulting
from

orthodontic
treatment.
The
European
Journal
of
Orthodontics,
1980.
2(1):
p.

19-‐25.

58.
Eismann,
D.,
A
method
of
evaluating
efficiency
of
orthodontic
treatment.
Trans

Europ
Orthod
Soc,
1974:
p.
223-‐232.

59.
Gottlieb,
E.L.,
Grading
your
orthodontic
treatment
results.
J
Clin
Orthod,
1975.

9(3):
p.
155-‐61.

60.
Berg,
R.,
Post-‐retention
analysis
of
treatment
problems
and
failures
in
264

consecutively
treated
cases.
The
European
Journal
of
Orthodontics,
1979.

1(1):
p.
55-‐68.

61.
Summers,
C.J.,
The
occlusal
index:
A
system
for
identifying
and
scoring
occlusal

disorders.
American
Journal
of
Orthodontics,
1971.
59(6):
p.
552-‐567.

62.
Richmond,
S.,
et
al.,
The
development
of
the
PAR
Index
(Peer
Assessment

Rating):
reliability
and
validity.
The
European
Journal
of
Orthodontics,
1992.

14(2):
p.
125-‐139.

63.
The
American
Board
of
Orthodontics
(ABO).
2011

[cited
2015
August];

Available
from:
http://www.americanboardortho.com.

64.
Moyers,
R.E.R.,
M.L.;
McNamara,
J.A.,
Standards
of
Human
Occlusal

Development.
1976,
Ann
Arbor:
The
University
of
Michigan,
Center
for

HUman
Growth
&
Dev.

65.
Swanson,
W.D.,
R.A.
Riedel,
and
J.A.
D'Anna,
Postretention
study:
incidence
and

stability
of
rotated
teeth
in
humans.
Angle
Orthod,
1975.
45(3):
p.
198-‐203.

66.
Little,
R.M.,
The
Irregularity
Index:
A
quantitative
score
of
mandibular
anterior

alignment.
American
Journal
of
Orthodontics,
1975.
68(5):
p.
554-‐563.

67.
Nadia,
L.,
et
al.,
Short-‐term
postorthodontic
changes
in
the
absence
of

retention.
The
Angle
Orthodontist,
2010.
80(6):
p.
1045-‐1050.

68.
Wiser,
G.,
Surgical
resection
of
supra-‐alveolar
fibers
and
the
retention
of

orthodontically
rotated
teeth
in
the
dog.
1961,
Temple
Univ.

45

69.
Van
der
Linden,
F.P.G.M.,
Theoretical
and
Practical
Aspects
of
Crowding
in
the

Human
Dentition.
J.
Am.
Dent.
Ass.,
1974(89):
p.
139-‐53.

70.
Harris,
E.H.,
R.Z.
Gardner,
and
J.L.
Vaden,
A
longitudinal
cephalometric
study
of

postorthodontic
craniofacial
changes.
American
Journal
of
Orthodontics
and

Dentofacial
Orthopedics,
1999.
115(1):
p.
77-‐82.

71.
Gardner,
R.A.,
E.F.
Harris,
and
J.L.
Vaden,
Postorthodontic
dental
changes:
A

longitudinal
study.
American
Journal
of
Orthodontics
and
Dentofacial

Orthopedics,
1998.
114(5):
p.
581-‐586.

72.
Perera,
P.S.G.,
Rotational
Growth
and
Incisor
Compensation.
The
Angle

Orthodontist,
1987.
57(1):
p.
39-‐49.

73.
Lundstrom,
A.,
Changes
in
crowding
and
spacing
of
the
teeth
with
age.
Dent

Pract
Dent
Rec,
1969(19):
p.
218-‐224.

74.
M.E.
Richarson,
J.S.G.,
Lower
arch
crowding
in
the
third
decade.
Eur
J
Orthod,

1998(20):
p.
597-‐607.

75.
Sinclair,
P.M.
and
R.M.
Little,
Dentofacial
maturation
of
untreated
normals.

American
Journal
of
Orthodontics,
1985.
88(2):
p.
146-‐156.

46

IX. Appendix

47

Figure:
Summary
of
orthodontic
rotational
movement
between
T1-‐T2
(above)
and

rotational
relapse
between
T2-‐T3
(below).

48

49

Case example #1003

50

Figure:
Summary
of
orthodontic
rotational
movement
between
T1-‐T2
(above)
and

rotational
relapse
between
T2-‐T3
(below).

51

52

Case%example%#1012
Figure: Initial (above) and final (below) intra-oral photos and stone models.

53

Figure:
Summary
of
orthodontic
rotational
movement
between
T1-‐T2
(above)
and

rotational
relapse
between
T2-‐T3
(below).

54

Abstract (if available)

Abstract Background: Relapse is an inevitable soliloquy of orthodontic treatment without proper retention. A better knowledge of how teeth relapse after appliance removal may help the orthodontic practitioner in choosing the most appropriate retention and relapse prevention therapy. Purpose: The aim of this study is to accurately assess the incidence of rotational relapse that takes place between appliance removal and retainer delivery to determine any patterns in relapse direction. Methods: Dental models from 13 consecutively de-bonded patients were compared at three time points: initial malocclusion, day of appliance removal, and 6-16 days later at retainer delivery. Initial models and models from the day of appliance removal were visually assessed to determine how the teeth were rotated into their corrected positions. To observe the direction these teeth relapsed, models from appliance removal and retainer delivery were digitally scanned and superimposed to create a 3D color map showing changes that occurred between the two time points. Results: Overall among the teeth that were moved orthodontically, the majority had no rotational relapse. The data suggests that teeth are nine times more likely to relapse in the opposite direction of orthodontic rotation than in the same direction. A large proportion of the teeth sampled were not moved orthodontically and did not relapse after appliance removal. Surprisingly, a small proportion of teeth relapsed even when not moved orthodontically from their initial malocclusion. Conclusion: Using the described methods, it is possible to conclude some trends in the direction of orthodontic rotational relapse. While most teeth will not relapse between appliance removal and retainer delivery, the orthodontic practitioner should be most aware of the potential for relapse in the opposite direction of orthodontic rotation.

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Asset Metadata

Creator Wong, Katherine (author)

Core Title Orthodontic rotational relapse: prevalence and prevention

School School of Dentistry

Degree Master of Science

Degree Program Craniofacial Biology

Publication Date 04/18/2016

Defense Date 02/05/2016

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag OAI-PMH Harvest,orthodontics,relapse,retention,rotation

Format application/pdf (imt)

Language English

Contributor Electronically uploaded by the author (provenance)

Advisor Sameshima, Glenn (committee chair), Grauer, Dan (committee member), Paine, Michael L. (committee member)

Creator Email wongka.usc@gmail.com,wongka@usc.edu

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c40-229573

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