Download Transposition of a canine to the extraction site of a dilacerated

CASE REPORT
Transposition of a canine to the extraction site
of a dilacerated maxillary central incisor
Antônio Carlos de Oliveira Ruellas,a Aluísio Martins de Oliveira,b and Matheus Melo Pithonc
Rio de Janeiro, Brazil
This article describes the treatment of a girl in whom anterior trauma during the deciduous dentition had
caused a dilacerated maxillary central incisor in the mixed dentition. The dilacerated central incisor was
extracted, and a canine was transposed to the extraction site. Canine transposition was performed so that
the lateral incisor could be maintained in its normal position. This article discusses the clinical implications
of dental dilacerations on orthodontic treatment and the treatment possibilities. (Am J Orthod Dentofacial
Orthop 2009;135:S133-9)
T
rauma of the anterior teeth is relatively common, occurring in a third of children during
the deciduous dentition.1 Because of the close
relationship between the apex of a deciduous tooth
and the permanent tooth germ, trauma of the former
can cause abnormalities in the formation of permanent teeth, either by a direct blow or by periapical
inflammation from dental trauma.2
The most common root orientation in patients
with dilacerated maxillary central incisors is a crown
that is directed labially and superiorly.3 Treatment depends on the degree of dilaceration, the position of
the tooth, and the patient’s motivation.3
Among the treatment options reported in the literature are (1) alignment or traction with removable1,4
or fixed3,5 appliances, with apicoectomy after traction6; (2) extraction of the central incisor and transposition of the lateral incisor; and (3) extraction of
the central incisor combined with canine transposition into the central incisor site.7
In this article, we describe a clinical situation in
which a patient had an impacted maxillary left cen-
a
Adjunct professor, Department of Orthodontics, Federal University of Rio de
Janeiro, Rio de Janeiro, Brazil.
b
Doctorate student, Department of Orthodontics, Stadual University of Campinas, Campinas, Brazil.
c
Doctorate student, Department of Orthodontics, Federal University of Rio de
Janeiro, Rio de Janeiro, Brazil.
The authors report no commercial, proprietary, or financial interest in the products or companies described in this article.
Reprint requests to: Antônio Carlos de Oliveira Ruellas, Department of Orthodontics, Federal University of Rio de Janeiro, Av. Brigadeiro Trompowsky
s/n, Ilha do Fundão, Rio de Janeiro, 21941590, Brazil; e-mail, antonioruellas@
yahoo.com.br.
Submitted, July 2007; revised and accepted, October 2007.
0889-5406/$36.00
Copyright © 2009 by the American Association of Orthodontists.
doi:10.1016/j.ajodo.2007.10.041
tral incisor with extensive root dilaceration, treated
by removing the dilacerated tooth, transposing the
canine, and transforming the canine into a central
incisor.
DIAGNOSIS AND ETIOLOGY
A healthy 10-year-old girl was brought to the
orthodontic clinic at Poços de Caldas, MG Brazil,
by her parents because she had a space between the
maxillary and mandibular teeth during occlusion, and
the maxillary left central incisor was not yet erupted.
Her parents reported that she had suffered anterior
dental trauma when she was 4 years old. At the initial
orthodontic evaluation, she was in the mixed dentition, with an Angle Class I malocclusion, an anterior
open bite of about 3 mm, a mouth-breathing habit,
and a maxillary dental midline deviation because of
the missing central incisor (Figs 1-4). The maxilla
was constricted slightly with no crossbite, and there
was a mandibular arch-length discrepancy of 6 mm.
The lateral cephalometric evaluation showed a Class
II skeletal malocclusion (ANB, 6°), vertical facial
growth (SnGoGn, 42°; y-axis–SN, 74°), retroclined
(1.NA, 16°) and lingually inclined (1-NA, 3 mm)
maxillary incisors, and facially inclined mandibular
incisors (1.NB, 29°, 1-NB, 5 mm, respectively), despite being well embedded in the mandible (IMPA,
89°). The facial profile was slightly convex (S-LS, +
1 mm; S-LI, + 1 mm).
Radiographs showed that the maxillary central incisor was impacted and inverted with a dilacerated root.
The angle between the root and the crown of the central
incisor was about 90°.
The patient had a previous thumb-sucking habit that
produced the anterior open bite that was perpetuated by
her tongue.
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Ruellas, Oliveira, and Pithon
American Journal of Orthodontics and Dentofacial Orthopedics
April 2009
Fig 1. Pretreatment photographs.
Fig 2. Pretreatment dental models.
TREATMENT OBJECTIVES
The treatment objectives for this patient were to
close the anterior open bite, correct the Class II relationship, retract the maxillary teeth, correct the mandibular
arch-length discrepancy, eliminate the dilacerated and
impacted incisor, and restore the normal appearance of
the maxillary anterior teeth.
TREATMENT ALTERNATIVES
1. Extract the dilacerated maxillary incisor and restore
with a fixed prosthesis or an implant.
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Ruellas, Oliveira, and Pithon
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Fig 3. Pretreatment cephalometric tracing.
Fig 4. Pretreatment radiographs.
2. Extract the dilacerated central incisor and close
the space with mesial movement of the lateral incisor, which would then be recontoured into a
central incisor.
3. Surgically expose and erupt the dilacerated central
incisor into the proper position.
4. Extract the dilacerated central incisor and transpose
the canine into the central incisor position.
TREATMENT PROGRESS
Comprehensive treatment was proposed, consisting
of extraction of the dilacerated maxillary central incisor
and canine-lateral incisor transposition, which would
require tooth recontouring, along with extraction of the
maxillary right lateral incisor and the mandibular left
and right first premolars. In addition, the patient was referred to an otorhinolaryngologist for evaluation.
After extracting the dilacerated maxillary central
incisor (Fig 5), a Haas-type modified appliance with a
tongue crib was placed to expand the maxillary arch and
guide the tongue into a more posterior position. After
this, the appliance was stabilized for 6 months, until
consolidation of the midlateral suture was completed.
After the stabilization period, the expansion appliance
was removed, and an appliance measuring 0.022 × 0.030
in was bonded to align the teeth in both arches. In addition,
an extraoral traction appliance was adapted to correct the
Class II skeletal malocclusion and for vertical control. Additionally, the maxillary right first premolar and the mandibular left and right first premolars were removed after
placement of the traction appliance, so that the teeth could
Fig 5. Dilacerated maxillary central incisor was extracted.
be better aligned over their osseous base. Surgical bonding
of the maxillary left canine was performed after extraction.
Initially, 0.16-in and 0.18-in archwires were used
for alignment and levelling as well as for canine retraction. After that phase, an 0.018 × 0.025-in stainless steel
wire was placed to enable greater rigidity and less deformation during retraction of the canines and closure
of the extraction spaces (maxillary right canine, mandibular left and right first premolars), movement of
the maxillary left canine, and the canine-lateral incisor
transposition into the central incisor site. Lingual torque
was applied to the maxillary left lateral incisor so that
its root could be palatally positioned, thus facilitating
the migration of the canine. The canine was transposed
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American Journal of Orthodontics and Dentofacial Orthopedics
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Fig 6. Transposition of the maxillary canine, followed by leveling and alignment.
at the same time as the extraction spaces were closed
(Fig 6, A). Once the maxillary canine was transposed, a
0.14-in nickel-titanium archwire was tied to the 0.018
× 0.025-in archwire to level the tooth in relation to the
adjacent teeth (Fig 6, B and C).
After incisor retraction by using a 0.019 × 0.025-in
archwire, new 0.019 × 0.025-in archwires were used to
provide ideal torque to the teeth. Near the transposed
canine, open-coil springs were placed mesially and
distally to increase the space to esthetically transform
the canine into a central incisor.
After active orthodontic treatment, the fixed appliance was removed, and a maxillary circumferential
retainer and a mandibular lingual bonded canine-tocanine retainer were given to the patient.
TREATMENT RESULTS
The orthodontic treatment closed the open bite, improved the tongue posture, created a Class I skeletal
relationship, improved the maxillary arch shape, and
improved the occlusion. The maxillary left central incisor was extracted, and the canine was transposed into
the space and restored as a central incisor.
These results show that it was possible to correct
the malocclusion and also to position the teeth over
their osseous bases sagitally, vertically, and anteroposteriorly (Figs 7-11).
DISCUSSION
About 54% of intrusive injuries to the anterior deciduous teeth can cause abnormalities in the developing permanent teeth.1 This includes anomalies such as
root dilaceration, which is an abnormal curve between
the crown and the root of a completely formed tooth.8,9
Dilacerations are seen most commonly in the maxillary anterior teeth,3 because this region is more likely
to suffer dental trauma during infancy. These traumatic
events occur in about 3% of the general population and
are 6 times more common in girls than in boys.10
Treatment of severe root dilacerations is lengthy,
complex, and expensive.8 Failures can be caused by
ankylosis, loss of periodontal insertion,6 and external
root resorption with root exposure after traction.5 A
careful treatment plan should be designed when dilacerated and impacted teeth are involved. Although various treatment alternatives are found in the literature,11
the most common approach for this malformation is to
extract the affected tooth12 and treat the resulting malocclusion orthodontically.13
Our objective in this article was to show a clinical case
in which a viable treatment option was adopted for severe
dilaceration of a maxillary central incisor. Extraction of
the dilacerated incisor with transposition of the canine
to the central incisor position was the treatment chosen.
Extraction of the central incisor was chosen because
of the extensive root dilaceration and its close proximity to the crown; this affected both tooth movement and
arch maintenance. If the central incisor had been uprighted, the dilacerated root would have projected out
of the labial mucosa. The success of this treatment option depends on the degree of dilaceration, the position
of the tooth, and the stage of tooth formation.5 Acute
angulation between crown and root as well as complete
root formation make the prognosis poor, thus leading to
extraction of the tooth, as for our patient.
Once extraction was considered, the possibilities of
postextraction treatments were reviewed: creating space
for a prosthesis (fixed appliance or implant), space
closure by mesial movement of the lateral incisor, canine-lateral incisor transposition, and transformation of
the canine into a central incisor. The canine was favorably positioned and had better root support compared
with the lateral incisor. All these factors contributed to
achieving the satisfactory results presented here.
The canine movement in this patient was made easier, because the tooth was already positioned toward the
mesial aspect, a phenomenon known as pseudo-transposition or incomplete transposition. This anomaly occurs
in 41.3% of all transposition cases.14
The esthetic results of the canine transposition
were satisfactory, and the canine shape was modified with restorative dentistry. By the end of this
patient’s treatment, lack of cooperation led to appli-
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Fig 7. Posttreatment photographs.
Fig 8. Posttreatment dental models.
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Fig 9. Posttreatment cephalometric tracing.
Fig 10. Posttreatment radiograph.
ance removal before complete finishing. More satisfactory root positioning of the maxillary left canine
could have been obtained with tip-back bends in the
archwire.
Esthetically and functionally, it is generally preferable to move the transposed teeth back to their
normal positions in the maxillary arch. But, in this
patient, the transposed canine allowed esthetic transformation of the central incisor, without mesial movement of the lateral incisor and without a prosthesis.
What happens to the functional occlusion when
the canine is placed in the central incisor position? In
this patient, the lateral contact in functional occlusion
was replaced by the maxillary premolar with no functional or esthetic compromises, as previously stated
by Silva Filho et al.15
In this patient, the vertical skeletal pattern was
maintained (SnGoGn, 40°; y-axis–SN, 73°) with
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April 2009
Fig 11. Superimposed cephalometric tracings.
tooth extractions and extraoral appliances so that extrusive forces could be avoided. In addition, the anteroposterior relationship of the osseous bases was
improved by the extraoral appliance as the Class II
skeletal malocclusion (ANB, 6°) was corrected to
Class I (ANB, 2°).
The maxillary arch shape was also improved with
both palatal expansion and tongue repositioning. The
patient’s facial profile was slightly altered because
of the dental retraction but without esthetic compromise.
The accentuated vertical facial pattern, the convex
profile, and the mandibular arch-length discrepancy
contributed to the need for tooth extractions. The extractions helped to prevent the open-bite relapse tendency.16 In addition, to minimize open-bite relapse,
myofunctional therapy was recommended at the end
of treatment. However, the long treatment time possibly led to cooperation problems, and the patient did
not have this therapy. The patient has been followed
for 2 years, and the esthetic and occlusal results have
been maintained satisfactorily.
CONCLUSIONS
Because the esthetic and functional results were
satisfactory in the clinical case described here, one can
conclude that a maxillary central incisor with severe
root dilaceration can be treated with incisor extraction
and canine-lateral incisor transposition, if there are precise indications for that treatment.
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