Uprighting impacted mandibular second molars using NiTi wire

Uprighting impacted mandibular second molars using NiTi wire

CONTINUING EDUCATION
Uprighting impacted mandibular second molars
using NiTi wire
Drs. Daniel DiBagno, Lauren Sigler Busch, and Daniel J. Rinchuse discuss uprighting impacted mandibular
second molars
T
he prevalence of ectopic eruption and/
or impaction of mandibular second
molars has been reported to range
from 0.3% to 2.3%.1,2,3,4,5,6 Recently, in
a Caucasian sample, Cassetta, et al.,7
found an incidence of 1.36% of mandibular
second molar impaction. There is ambiguity
in the prevalence data reporting because
second molar impaction rates may be
grouped together, maxillary and mandibular,
while other sources do not distinguish
impactions from ectopic eruption. Moreover,
the definition of impaction versus ectopic
eruption varies in the orthodontic literature.
According to the American Association of
Orthodontists (AAO) Glossary of Orthodontic
Terms, an impaction is “a condition that
describes the total or partial lack of eruption
of a tooth well after the normal age for
eruption,” whereas ectopic is defined as
“located away from normal position” or a
“condition in which a tooth develops or
erupts in an abnormal position.”8 Other
researchers use the term ectopic to describe
a tooth that could potentially erupt into the
arch.9 Using this definition, a percentage of
ectopically erupting teeth have the ability to
self-correct over time into a normal position,
whereas impacted teeth remain as such.
The definition of ectopic eruption can be
made only theoretically or in hindsight
and, therefore, is an enigmatic orthodontic
definition. Therefore, for the purposes of this
paper, we will group the two terms together
as impaction. Mandibular molar impaction
is more likely to occur unilaterally than
bilaterally. The impaction occurs more often
on the right side than the left side. Impacted
Daniel DiBagno, DMD, is Assistant Professor and Director of
Clinical Training at Seton Hill University Graduate Program in
Orthodontics, Greensburg, Pennsylvania. To contact Dr. DiBagno,
email [email protected].
Lauren Sigler Busch, DDS, is a graduate orthodontic resident at
Seton Hill University.
Daniel J. Rinchuse, DMD, MS, MDS, PhD, is Professor and
Program Director at Seton Hill University.
34 Orthodontic practice
Educational aims and objectives
This article aims to discuss uprighting impacted mandibular second molars using NiTi wire.
Expected outcomes
Orthodontic Practice US subscribers can answer the CE questions on page XX to
earn 2 hours of CE from reading this article. Correctly answering the questions will
demonstrate the reader can:
• Realize the prevalence of ectopic eruption and/or impaction of mandibular
second molars.
• Identify some of the causes of eruption problems.
• Identify some environmental factors associated with impaction.
• Realize some of the challenges of treating mandibular second molars.
• Read about the authors’ method for dealing with ectopic eruption and impaction of mandibular second
molars in young patients.
second molars are most often inclined
mesially.10 There appears to be no gender
predisposition to mandibular second molar
impaction11 although some studies report a
male predisposition.4
Eruption problems can be due to genetic
or environmental problems, specifically
ectopic position or eruption path obstacles.12
Genetic causes of eruption disturbances
remain elusive. While Parathyroid Hormone
Receptor 1 PTH1R has been associated with
Primary Failure of Eruption,13 specific genetic
mutations that are associated with second
molar impaction have not yet been identified. However, impaction of the mandibular
second molar has been demonstrated to
have an autosomal dominant inheritance
pattern in Chinese Americans.6 Shapira, et
al.,6 found that certain races have higher
prevalence of impaction than others; for
instance, 2.3% in Chinese American populations versus Israeli populations (1.4%).The
same study also found reduced mesial root
length of the mandibular second molar to be
associated with its impaction.
Environmental factors associated with
impaction include crowding,7 supernumerary
teeth, odontomas, cysts, or ectopic positions of the teeth in the deciduous dentition.5
Iatrogenic reasons for mandibular second
molar impaction are use of appliances that
maintain arch perimeter, such as the lower
lingual holding arch and/or the Schwarz
appliance,14 and incorrectly fitted bands.15
In a small sample, Evans showed an increase
in second molar impaction prevalence from
1976 to 1986.16 The increased popularity
of nonextraction treatment during the time
period of the study translated into a decrease
in extraction rates. It is postulated that the
increase in nonextraction treatment during
this time period also led to an increased
prevalence of mandibular second molar
impaction.7 Ectopic eruption of the second
molars can cause multiple problems, such as
resorption, pain, increased orthodontic treatment time, increased caries susceptibility,
malocclusion, and periodontal disease.11
Mandibular second molars can oftentimes be frustrating for orthodontists. Not
only is it difficult for the practitioner to work
in the posterior of the mouth while maintaining a dry field to bond brackets, impacted
mandibular second molar(s) may only be
partially erupted, so placing a bracket is often
problematic or impossible. Many methods
and procedures have been reported in the
orthodontic literature for uprighting mesioangular impacted mandibular second
molars such as surgical methods involving
extraction of third molars, extraction of the
second molar, and autotransplantation.17
Other methods involved miniscrews/miniplates.18,19 Conservative approaches to
correct mandibular second molar impaction
include uprighting springs,15 tip-back cantilevers coupled with buccal exposure,15 pins,20
chain-activated auxiliaries,21 and separating
Volume 6 Number 2
Appliance design and protocol
In 2011 there were two published32,33
descriptions of a non-surgical technique
for uprighting mesially impacted mandibular
molars. Bach32 used an .014" x .025" Copper
NiTi wire, whereas about the same time the
author (DD), independently, developed a
similar technique using .016" x .016" NiTi
wire. The two previous descriptions of the
technique did not include a literature review
like this current paper and did not discuss a
broader utility of the technique.
To initiate uprighting, acid etch the first
molar occlusal surface and the occlusal onethird of its distal surface for 30-60 seconds,
rinse, dry and isolate to maintain a dry
Volume 6 Number 2
working field. Cut a 10-12 mm section of
.016" x .016" nickel-titanium wire, and hold
it at approximately the midpoint of the wire
using either a Mathieu ligating plier or Weingart utility plier. Topical anesthesia and/or
local infiltration of a dental anesthetic can
be used when performing this procedure,
but it is typically not necessary. The author
(DD) has performed this procedure multiple
times and has never used anesthetic.
Gently pass the wire gingivally between the
erupted first and impacted second molars,
carefully following the distal contour of the
first molar with the leading edge of the wire
while sliding the wire in a gingival direction.
In most instances, only 3-4 mm of wire will
pass gingivally before resistance is felt. When
resistance is felt, stop the gingival movement,
and bend the occlusal portion of the wire
mesially and downward, and hold it (with
a ligature director) in the central groove of
the first molar while your assistant places a
couple small dabs of Band-Lok® (Reliance
Orthodontic Products) over the wire, being
careful not to get any Band-Lok on the ligature director. Light cure, release your hold
with the ligature director, and take a periapical radiograph, if desired, to verify correct
wire placement. If the radiograph reveals
improper wire placement, remove the BandLok from the occlusal surface of the first
molar, and repeat the procedure making the
necessary directional adjustments. When the
radiograph reveals proper wire placement,
re-isolate and dry the occlusal surface of the
first molar along with the occlusal third of its
distal surface, and add sufficient Band-Lok to
the occlusal surface to form a posterior bite
turbo to disocclude the posterior teeth and
protect the working sectional nickel-titanium
wire. In addition, also apply a small amount of
Band-Lok over the wire as it descends along
the occlusal one-third of the distal surface
of the first molar. This helps prevent buccal
or lingual movement and dislodgement of
the working wire as the second molar is
uprighting. When performing the procedure
unilaterally, a bite turbo of equal size should
be added to the first molar on the opposite
side of the arch for patient comfort.
The patient should be seen every
2-3 weeks to monitor the second molar
uprighting progress. When allowed to go
longer than 2-3 week intervals, the author
(DD) has sometimes observed the leading
edge of the working wire disengage from
the second molar and the second molar
“relapse” into its original position. At each
follow-up appointment, a periapical radiograph should be taken to assess the position of the leading edge of the working wire
and the position of the second molar. If the
crown of the second molar is not sufficiently
exposed in the oral cavity to permit bracket
placement, the orthodontist must decide
either to continue the uprighting process with
the current wire or to replace it with a wire of
longer length to prevent the disengagement
of the leading edge of the working wire from
the mesial surface of the uprighting molar. In
the majority of cases, 2-4 appointments 2-3
weeks apart (4-12 weeks total) are sufficient
to upright the second molar enough to place
a bracket on the tooth.
Case reports
A 12-year 10-month-old male presented
with a chief complaint of “I have crooked
teeth and don’t like my smile.” Intraoral
examination revealed an Angle’s Class I
malocclusion with mild maxillary and mandibular anterior crowding, minimal overjet, and
a severe (100%) impinging overbite with
partially blocked out, but favorably positioned
and unerupted, maxillary and mandibular
canines. The panoramic radiograph (Figure
1) revealed unerupted and mesially angulated mandibular second molars seemingly
Figure 1: Panoramic radiograph revealing unerupted mesially angulated mandibular second molars
Orthodontic practice 35
CONTINUING EDUCATION
wires.22 Many methods require the tooth to
have one or more of the cusps exposed
or present to place an uprighting appliance.23,24,25,26 Greater success is reported in
younger patients, suggesting that the earlier
the anomalous eruption is treated, the higher
the success rate. The recommended age
to treat the mandibular molar impaction is
between age 11 and 14.27,28,29 More specifically, it is best to treat the impaction when
mandibular second molar root formation is
not yet complete.15
Conservative treatments of second
mandibular molar impaction are successful
in roughly 50% of cases.30 However, this
data is skewed as it includes surgical
combination treatment as well as maxillary
impaction rates. In a retrospective follow-up
study of impacted second molars (maxillary and mandibular) Magnusson and Kjellberg31 found the least successful treatment
(11%) was extraction of the second molar
to permit the third molar to replace it, while
the most successful treatment (71%) was
surgical exposure of the second molars.
Valmaseda-Castellon, et al.,30 found conservative treatments for first and second molar
impaction, which included surgical exposure,
orthodontic traction, surgical luxation and
orthodontic traction, restoration, transplantation, or no treatment, resulted in a 50%
success rate in 14- to 20-year-old patients.
More studies are needed to evaluate the
success rates of orthodontic treatment for
mandibular second molar impaction.
This paper demonstrates a simple,
cost-effective, pain-free, and conservative
method for dealing with ectopic eruption and
impaction of mandibular second molars in
young patients. This procedure is not appropriate for mandibular second molars that are
afflicted with primary failure of eruption or
secondary retention.
CONTINUING EDUCATION
trapped in the distal crown-root concavity
of the erupted first permanent molars on
both sides. The developing crowns of both
mandibular third molars appeared to overlap
the distal surfaces of both unerupted permanent second molars.
Both arches were bonded from first
molar to first molar; and after leveling, alignment, and bite opening, space was made
for the unerupted maxillary and mandibular
canines. The canines were bonded upon
eruption, and at that time, the mandibular
right second molar was visibly erupting.
However, the mandibular left second molar
was not visible, and a panoramic radiograph (Figure 2) revealed it to continue to be
mesio-angulated and impacted in the distal
crown-root concavity of the permanent first
molar with the developing crown of the third
molar resting against its distal surface. At
a subsequent appointment, a 10-12 mm
section of .016" x .016" nickel-titanium wire
was inserted between the impacted second
molar and first molar and bonded to the first
molar occlusal surface as described in the
previous section (Figures 3 and 4). At the
next appointment, 3 weeks later, the crown
of the erupting mandibular left second molar
was visible in the oral cavity (Figure 5). At this
Figure 2: Panoramic radiograph revealing meso-angulated and impacted left mandibular second molar
Figure 3: Periapical radiograph of .016 x .016
nickel-titanium wire inserted subgingivally to
upright impacted second molar
Figure 5: Intraoral photograph revealing the crown of the previously
impacted mandibular second molar. The second molar was uprighted
using the NiTi wire technique described
Figure 8: Periapical radiograph at the end of treatment
revealing upright mandibular left second molar
36 Orthodontic practice
Figure 4: Intraoral photograph of .016 x.016 nickel-titanium wire inserted
distally and subgingivally to the mandibular first molar. The wire is bonded
to occlusal surface of the mandibular left first molar
Figure 6: Periapical taken at time of separator placement following use of NiTi wire
uprighting technique
Figure 7: Intraoral photograph of separator placement after crown
eruption of mandibular left second molar. The separator has been
placed to continue uprighting the mandibular left second molar
Figure 9: Posttreatment panoramic X-ray revealing upright mandibular left second molar
Volume 6 Number 2
Figure 11: Panoramic radiograph revealing meso-angulated impacted mandibular left second molar
Figure 12: Periapical radiograph of NiTi wire engaged in
mesial occlusal pit of impacted mandibular second molar
Figure 13: Periapical radiograph taken to monitor progress
of impacted mandibular second molar. The angulation and
position of the molar has improved
point in treatment, the NiTi was removed, and
an elastic separator was placed between the
mandibular left first and second molars for
one visit (3 weeks) to complete the uprighting
process (Figures 6 and 7). The mandibular
left second molar was now in alignment
(Figure 8), and the case was completed in the
usual manner. Final radiographs and photos
revealed an upright mandibular left second
molar with the third molar still present and a
total treatment time of 24 months (Figures
9 and 10).
The second patient is a 13-year
1-month-old female who presented with
a chief complaint of “My front teeth don’t
overlap.” Intraoral examination revealed an
Volume 6 Number 2
Figure 14: Intraoral photograph revealing the crown of the left mandibular second molar beginning has erupted into the
oral cavity
Angle’s Class I malocclusion with a mild anterior open bite, mild maxillary and mandibular
arch crowding, delayed development of
the mandibular right second molar, and a
mandibular left second molar with normal
development and mesio-angulated impaction. (Figure 11).
Prior to the bonding of fixed appliances,
a 10-12 mm section of .016" x .016" nickeltitanium wire was inserted between the
impacted second molar and the erupted first
molar and bonded to the occlusal surface of
the first molar as described in the appliance
design and protocol section. However, due
to the angulation of the impaction, it was
not possible to follow the distal contour of
the mandibular first molar with the leading
edge of the nickel-titanium section of wire.
Therefore, the wire was engaged in the mesial
occlusal pit of the impacted second molar
(Figure 12). The patient was seen 17 days
later to monitor her progress, and another
periapical radiograph was taken to assess
the uprighting progress (Figure 13). At this
appointment a new, slightly longer, section
of .016" x .016" nickel-titanium wire was
inserted between the molars and secured
to the occlusal surface of the first molar with
Band-Lok. The patient was seen 25 days
later, and the previously impacted second
molar was visibly erupting into the oral cavity
(Figure 14). Shortly afterward, comprehensive treatment was initiated, and the maxillary
and mandibular arches were bonded from
first molar to first molar. Four months later, a
progress panoramic radiograph was taken
Orthodontic practice 37
CONTINUING EDUCATION
Figure 10: Posttreatment intraoral photograph revealing
upright mandibular left second molar
CONTINUING EDUCATION
Figure 16: Intraoral photograph demonstrating the crown of
the previously impacted left mandibular second molar has
nearly completely erupted into the oral cavity
Figure 15: Progress panoramic radiograph confirming the left mandibular second molar has fully erupted into the oral cavity
to assist in bracket repositioning (Figure 15).
An occlusal photo taken on the same day
shows the previously impacted mandibular
left second molar erupting into the oral cavity
(Figure 16). An elastic separator was then
placed between the mandibular left first and
second molars in an attempt to finalize the
uprighting process. In the near future, it may
also be necessary to bond a bracket to the
mandibular left second molar to complete
alignment. It may also be necessary to
perform the same uprighting procedure on
the patient’s slow-developing mandibular
right second molar towards the end of active
treatment and/or during retention.
Discussion
With the decline in extractions in recent
years,34 ,35 and a bias toward nonextraction
treatment, impaction of second molars,
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particularly mandibular second molars may
increase. E-space preservation (primary
second molar space), as it is often called in
the orthodontic literature, in a nonextraction
protocol with a passive lingual arch is 10 to
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The advantages of the technique for
uprighting second molars described in this
paper are as follows:
• Relatively painless
• Inexpensive
• Efficient
• Effective
• Places little burden on the patient
• Low-maintenance.
With this technique, it is not necessary, as
the case reports demonstrate, to extract the
third molars prior to uprighting. A major advantage of this technique is that it can be performed
on a bonded or unbonded mandibular arch.
Instead of waiting many years and keeping
orthodontic appliances on for an extended
period of time until mandibular second molars
erupt, impacted mandibular second molars
can be uprighted before, during, or after active
orthodontic treatment treatment. The reciprocating effects on the mandibular first molar are
minimal since the opposing occlusion of the
maxillary arch prevents supra-eruption. When
using this procedure on a bonded mandibular
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bonding appointment or at any time during the
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22. Aksoy AU, Aras S. Use of nickel titanium coil springs for partially
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Volume 6 Number 2