Download Correction of a Class III malocclusion with over 20

CASE REPORT
Correction of a Class III malocclusion with
over 20 mm of space to close in the maxilla
by using miniscrews for extra anchorage
K. Hero Breuning
Tiel, the Netherlands
Unilateral closure of maxillary extraction spaces in patients with Class III malocclusion can be challenging.
This case report describes the closure of first premolar and first molar extraction spaces in a patient with a
Class III dental relationship. Two miniscrews were used for intraoral skeletal anchorage. The Class III dental
relationship was corrected; a positive vertical overbite was achieved; occlusion of the canines, premolars,
and molars was improved; and the extraction spaces were closed. (Am J Orthod Dentofacial Orthop 2008;
133:459-69)
U
nilateral closure of a large maxillary extraction
space in a patient with a Class III dental
relationship can be a serious orthodontic challenge. The use of miniscrews for skeletal anchorage
during orthodontic treatment, originally introduced by
Creekmore and Eklund,1 allows large extraction spaces
to be closed during treatment, without detriment to the
position of the anterior teeth.
DIAGNOSIS AND ETIOLOGY
The patient, a boy aged 13 years 6 months, was
referred by his dentist for correction of his malocclusion (Figs 1-4). Clinical evaluation indicated a skeletal
Class I pattern and a midline shift of the mandible by 3
mm to the right. Overbite and overjet were approximately –1 mm, and the right canine was out of
occlusion; the occlusion of the right canines and the
first molar was a Class III relationship. There was no
crowding in either dental arch.
The facial photographs show a mild Class III facial
appearance, a chin deviation of 3 mm to the right, and
incompetent lips at rest. The patient reported no history
of mandibular prominence in the family. Intraoral
photographs and dental casts showed the extent of the
2 extraction spaces in the maxillary arch. The panoramic radiograph showed all teeth present, but there
was extensive caries in the maxillary left first premolar
and first molar. The patient’s general practitioner
Private practice, Tiel, the Netherlands.
Disclaimer: The combination of active and passive self-ligating brackets in
combination with miniscrews, called the Hero System, was developed by the
author. He reports no commercial relationship with a specific company.
Reprint requests to: K. Hero Breuning, Tolhuiswal 33 4001 LL, Tiel, the
Netherlands; e-mail, [email protected].
Submitted, June 2006; revised and accepted, August 2006.
0889-5406/$34.00
Copyright © 2008 by the American Association of Orthodontists.
doi:10.1016/j.ajodo.2006.08.019
thought that both teeth were beyond repair and should
be extracted. The resulting large extraction spaces
would need to be restored with implants or bridges, or
closed orthodontically.
The cephalometric tracing and analysis (Fig 4,
Table I) showed an SNA angle of 77.6°, indicating a
retrognathic maxillary complex. The ANB angle, however, was normal at 3°. The maxillary incisors were
retroclined, and the mandibular incisors were slightly
proclined. The Wits appraisal indicated a normal Class
I relationship.
TREATMENT OBJECTIVES
The treatment objectives for this patient were to
correct the Class III incisor relationship; achieve a
positive vertical overbite; improve the occlusion of the
canines, premolars, and molars; close the extraction
spaces; finish; and retain.
TREATMENT ALTERNATIVES
Correction of the malocclusion would involve traditional orthodontic treatment with fixed appliances in
both arches. A combined orthodontic/orthognathic approach after growth was initially considered. The patient had a mild skeletal Class III relationship, but
cephalometric measurements were within the normal
range, and no prominent jaws were reported in the
family. Development of a more severe Class III skeletal
relationship was thought unlikely; therefore, delaying
the start of treatment to observe the need for surgical
correction of the skeletal relation was not indicated.
Closure of extraction spaces closure was the most
challenging aspect, particularly because of the Class III
incisor relationship. Correction of the occlusion without
closing the spaces was, of course, an option, but this
treatment plan would require prosthetic restoration of the
459
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American Journal of Orthodontics and Dentofacial Orthopedics
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Fig 1. Pretreatment extraoral and intraoral photographs.
dentition after orthodontic treatment. Because of the
patient’s age, alveolar growth after orthodontic treatment
would be expected; temporary prosthetic devices would
be needed to fill the spaces in the maxillary arch until
dental implants could be used for a definitive solution.
If feasible, closure of 1 extraction space or both
would be the treatment of choice.
TREATMENT PLAN
Orthodontic mechanics with significantly reduced
friction in the molar and premolar regions were desirable because less friction would help reduce the force
needed to close the extraction spaces. Molar and
premolar tubes were used (Fig 5).
Two miniscrews (1 between the maxillary left
lateral incisor and the canine; the second just distal to
the canine) were placed to significantly enhance anterior anchorage during protraction of the maxillary left
second premolar and the second molar. Interarch elastic
traction would be used to help with correction of
overjet, overbite, and occlusion.
TREATMENT PROGRESS
The maxillary teeth were bonded with a .022-in
preadjusted self-ligating bracket system. In the maxillary incisors and canines, interactive self-ligating
brackets were used. In the maxillary premolars and
molars, bonded tubes were placed. Tip and torque
values used in this patient are listed in Table II.
A continuous .014-in nickel-titanium-selenium
wire, with a dimple between the maxillary central
incisors to prevent sliding, was used during the first
phase of treatment.
After leveling, which took only 8 weeks, a .016 ⫻
.025-in nickel-titanium-selenium wire was used for
further correction of rotations, tip, and torque of the
maxillary teeth. One month later, a panoramic radiograph was taken to help determine the position of the
miniscrews (Fig 6).
Miniscrews (diameter, 1.6 mm; length, 10 mm)
were considered ideal for this patient, and he was
referred to the maxillofacial surgeon for placement of 2
miniscrews under local anesthesia. One was placed
between the maxillary left lateral incisor and the
canine, and the second just distal to the canine.
Immediately after surgery, a ligature was used to
connect the miniscrew to the maxillary left canine to
increase the anchorage value of this tooth (Fig 7). A
nickel-titanium spring was then used to provide gentle
forces to protract the second premolar and the second
molar simultaneously. Those teeth had been previously
linked together with a steel ligature. At the next visit, even
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Fig 2. Pretreatment dental casts.
Fig 3. Pretreatment panoramic radiograph.
with the miniscrew to stabilize the position of the canine,
some distalization was observed (Fig 8). Because of this
loss of anchorage, the mechanical system was changed.
Direct loading of the mesial miniscrew with the same
nickel-titanium spring might have helped to protract the
second premolar and the second molar, but without the
reciprocal distalizing force on the canine.
Fig 4. Pretreatment cephalometric tracing.
462 Breuning
Table I.
American Journal of Orthodontics and Dentofacial Orthopedics
March 2008
Pretreatment and posttreatment cephalometric
Table II.
Torque, angulation, and tip values
values
SNA angle
SNB angle
ANB angle
Y-axis
U1 to ANS-PNS
SOB
VOB
U1 to FOP
L1 to FOP
LI to MP
SN to MP
Wits appraisal
Pretreatment
Posttreatment
77.6°
74.5°
3.0°
70.2°
98.6°
0.3 mm
⫺1.0 mm
⫺0.4 mm
⫺0.6 mm
97.3°
35.6°
0.1 mm
78.3°
74.9°
3.4°
72.2°
100.3°
3.0 mm
1.6 mm
⫺1.1 mm
0.5 mm
99.5°
35.2°
0.7 mm
SOB, overjet; VOB, overbite; FOP, functional occlusal plane.
Maxilla
Central incisors
Lateral incisors
Canine with hooks
First and second premolar
tubes (⫹ hooks)
First and second molar tubes
(⫹ hooks)
Mandible
Anterior teeth
Canines with hooks
First premolar
Second premolar tubes with
hook
First molar tubes with hooks
Second molar tubes with hooks
Torque
Angulation
⫹12°
⫹8°
⫺2°
⫺7°
⫹5°
⫹9°
⫹9°
⫹0°
⫺10°
⫹0°
⫺1°
⫺2°
⫺11°
⫺17°
0°
⫹7°
0°
0°
⫺20°
⫺20°
0°
0°
Rotation
10°
Fig 5. Brackets and tubes (Hero system) used in this
patient.
As a result of the direction of the applied traction,
an open bite started to develop (Fig 9). It was decided
at this stage to use a sliding hook with a long arm
placed distal to the second premolar to provide the
force to protract it. For protraction of the second molar,
a nickel-titanium spring connected to the distal miniscrew and the second molar was used.
For evaluation purposes, a panoramic radiograph was
taken (Fig 10). Controlled protraction of the second
premolar and the second molar (without tipping of the
roots) was confirmed. Extraoral photographs were used to
evaluate facial changes (Fig 11). Fixed appliances were
placed in the mandible to correct the sagittal and vertical
relationships between the arches. Protraction of the second
premolar and the second molar was finally hindered by the
position of the miniscrews, and they were removed,
without anesthetic, during a regular appliance check visit.
No pain or discomfort was reported, either during or after
removal. Once the miniscrews had been removed, final
correction of the malocclusion occlusion was achieved
with the help of interarch elastics.
At the end of treatment, the maxillary dental midline was positioned in line with the facial midline, but
Fig 6. Panoramic radiograph during treatment.
the mandibular dental midline was not coordinated with
the maxillary midline, because of the underlying mandibular asymmetry.
The panoramic radiograph (Fig 12) shows good
position of the roots with no root resorption evident.
The maxillary left third molar should erupt in occlusion
with the mandibular second molar. The second mandibular molar overerupted slightly during the first few
weeks after treatment; the overeruption was identified
at the first posttreatment check visit, and a fixed retainer
was used to prevent further eruption (Fig 13).
The posttreatment cephalometric tracing and cephalometric values are shown in Figure 14 and Table I.
Superimposed tracings (Fig 15) show the differences in
the position of the maxillary left second molar before
treatment. The maxillary superimposition shows the
position of the left second molar and the most prominent maxillary incisor, and the mandibular superimposition shows the position of the first molar and most
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Fig 7. Intraoral photographs immediately after miniscrew placement.
Fig 8. Intraoral photograph showing loss of anchorage of canine.
Fig 9. Intraoral photograph showing bite opening.
Fig 10. Panoramic radiograph showing miniscrews and
roots during protraction.
prominent incisor. Posttreatment extraoral and intraoral
photos were taken during the first retention visit, 8
weeks after removal of the appliance (Fig 16). Retention consisted of a fixed retainer in the mandibular arch
and an Essix (Raintree, Seoul, Korea) retainer in the
maxillary arch (Fig 17). During settling, the occlusion
Fig 11. Frontal extraoral photograph during treatment.
changed. Plaster study models taken 6 months posttreatment (Fig 18) show coordinated midlines.
The total active treatment time was 1 year 6 months.
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Fig 12. Posttreatment panoramic radiograph.
Fig 13. Closeup of retention of the mandibular left
second molar to prevent eruption.
DISCUSSION
The main problem in treating this patient was the
excessive extraction spaces in 1 side of the maxillary
arch with no crowding and no overjet. Closing this
extraction space, without a detrimental effect on the
maxillary arch form, and correcting the interarch relationships were extremely tall orders.
The etiology of this malocclusion was mainly
genetic, with a small retropositioned maxilla. Treatment was complicated by the extreme dental decay.
The patient needed medication early in his life for
severe asthma; this might have contributed to the
decay, but the medical history was not clear. He was
not a regular dental patient. Before any orthodontic
treatment was attempted, dietary habits and oral hygiene were discussed with him and his parents. During
active treatment, the patient was asked to use a fluoride
rinse daily to prevent further tooth decay.
Anchorage
At least a quarter of the extraction space is routinely
occupied by the anchor teeth during orthodontic treatment unless measures are taken to supplement this
anchorage.2 Absolute anchorage was needed to prevent
retraction of the maxillary incisors and worsening of
Fig 14. Cephalometric tracing 6 months after treatment.
the Class III incisor relationship. Ideally, the maxillary
incisors would be moved forward during orthodontic
treatment to correct overjet and overbite.
Anchorage loss is related to the forces needed to
protract the premolar and the second molar. If a bracket
system with lower friction is used, less force will
theoretically be needed to protract the teeth, and therefore less anchorage loss can be expected.3
Self-ligating brackets were introduced in the mid1930s in the form of the Russell attachment (United States
Patent 6302688). Two types of self-ligating brackets are
popular: those with a self-ligating clip that does not press
against the wire (passive), such as the Damon and Smart
Clip brackets, and those with a clip that presses against the
wire if a larger wire is used (interactive), such as Speed,
System R, and Time brackets.
In this patient, a combination of passive and interactive brackets was used. A combination of rectangular
wire and interactive brackets (Time; American Orthodontics, Sheboygan, Wis) was used to correct the
torque of the incisors, overjet, and overbite. Passive
brackets (Nr 098-1510C, Nr 098-1511C; Hero tubes)
were used to protract the premolar and the molar in the
maxillary arch. Elastic forces were also used to counteract tongue and lip pressure and close the bite.
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Several studies demonstrated significant decreases
in friction for self-ligating brackets, compared with
conventional bracket designs, by using elastics or steel
ligatures.4-7
The use of premolar and molar tubes in this patient
contributed to a mechanical system that required low
forces to move the teeth. When temporary anchorage
devices are used, a low force system is recommended.8,9
It has been suggested that reduced friction can help
to shorten treatment time, especially in extraction
patients in whom tooth translation is achieved by
sliding mechanics.
Anchorage alternatives
Fig 15. Superimposed tracing before and after treatment. Maxillary superimposition shows the position of
the maxillary left second molar and the mandibular
incisors, before and after treatment.
Extraction of the right first premolars in the maxilla
and the mandible was also considered, but, because of
the patient’s Class III profile, cephalometric values,
dental relationships, and the absence of crowding in the
arches, this treatment alternative was rejected. Closing
of all spaces in the left side of the maxilla during
correction of the occlusion, without compensating extractions, required additional anchorage. A facemask to
provide this extra anchorage was considered, but,
because of the patient’s age, sufficient compliance in
using it during treatment could not be guaranteed, and
he was not keen about this approach. Furthermore,
anchorage was needed only on the left side of the
maxilla, so it was a unilateral problem.
The use of a standard dental implant in the first
premolar region for temporary anchorage during orthodontic tooth movement to protract the maxillary left
second molar, and then as a permanent abutment for tooth
replacement, was reported and was considered.10-15
The patient’s age would have necessitated additional time for osseointegration, and this, in addition to
the costs of the implant and the crown, meant that this
approach was rejected.
Several temporary anchorage devices for orthodontic
anchorage have been introduced.16-18 In this patient,
several temporary anchorage devices could have been
used. A palatal implant was described for absolute anchorage during orthodontic treatment and can be used for
various orthodontic procedures such as en-masse retraction of the 6 anterior teeth or canine distalization without
anchorage loss.19-21 The position of a palatal implant is
not the most suitable place for skeletal anchorage to
protract a second premolar and molar, and this treatment
option was rejected in this patient. There were other
disadvantages to a palatal implant for this patient, such as
the extra time needed for its integration, the costs of the
implant, and the discomfort of surgical placement and
removal.
Miniplates can be used to help protract the denti-
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Fig 16. Posttreatment extraoral and intraoral photographs (at 8 weeks).
Fig 17. Intraoral photographs of retainers.
tion.22-27 Because titanium miniplates have been thoroughly evaluated as a biocompatible material and used
for surgical procedures, they can also be used for
improving orthodontic anchorage.
However, the implant side must have sufficient
cortical bone. In the maxillary region around the
incisors, cortical bone depth is often lacking.
Another disadvantage of miniplates for anchorage
is the more complicated surgical procedure, including a gingival flap during fixation and removal of the
device.
Miniscrews can be used for additional anchorage
during fixed appliance treatment.27-30 In this patient,
the placement of 2 miniscrews (Jeil Medical, Seoul,
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Fig 18. Dental casts, 6 months after treatment.
Korea) was considered the most suitable treatment
option. The surgical procedure required only local
anesthetic, no gingival flap was required, miniscrews
are relatively inexpensive, and miniscrews can be
removed in the orthodontic office without anesthesia.
Surgical procedure
When orthodontic treatment including miniscrews
is planned, a protocol for their use should be followed,
but there is no widely accepted protocol yet.31-38
Our team’s procedure for placing miniscrews usually uses these guidelines. The patient rinses with a
chlorhexide solution for at least 1 minute before surgery. Local anesthetics are administered, and selftapping screws are used without predrilling, unless the
cortical bone is excessively thick. In that case, predrilling of the cortical bone only is sufficient. Manual
screwdrivers are always used, and the junction of the
attached gingiva and the reflected mucosa is considered
to be the ideal site. The miniscrew is placed at an angle
of up to 45° to the cortical plate. Primary stability,
indicated by the screw’s resistance to lateral movement,
is desirable. If primary stability is not achieved, a larger
screw, a different location, or an additional screw
should be considered. After surgery, the patient is
instructed on the maintenance of the miniscrews and
referred to the orthodontist for the application of
orthodontic force. Immediate loading with a gentle
force from a nickel-titanium spring (within several
hours of surgery) is recommended.
In our opinion, the orthodontist is responsible for
postoperative instruction on screw cleaning and what
the patient should do in case of screw failure.
Relatively low forces should be used, and therefore
sliding mechanics and bracket systems with low friction are recommended. Intermittent forces should certainly be avoided. Continuous forces (nickel-titanium
springs, nickel-titanium wires, power chain, E-links)
can all be used effectively.
Treatment after the surgical procedure
A nickel-titanium coil spring (with a constant force
of 100 g) was used to protract the second premolar and
the second molar. In this patient, the initial treatment
mechanics and the strengthening of the anchorage of
the maxillary left canine were not outstandingly successful. Changing the force mechanism to direct loading of the miniscrew was successful. Changing the
force mechanism again was also needed to correct the
open bite caused by the vertical component of traction.
468 Breuning
The use of 2 miniscrews placed bucally in the interradicular bone necessitated removal of the screws after
space closure. The miniscrew at some point in treatment
causes an obstruction to complete the space closure and
should then be removed. These miniscrews will be osseointegrated, but, because their surface is polished, they
can be easily removed without anesthesia.39,40
Retention
Retention after orthodontic treatment is almost
invariably needed. In this patient, a fixed retainer in the
mandible was used for permanent retention.
In the maxillary arch, there can be a tendency for
spaces to reopen if the treatment result is not retained.
A wraparound retainer was used in this patient. After
the eruption of the maxillary left third molar, daily use
of the retainer might be no longer be necessary to
prevent reopening of the extraction spaces, and alternative retention can than be considered. The correction
of the dental midlines, as observed 6 months after
treatment during the clinical posttreatment evaluation,
was remarkable.
The author thanks Jonathan Sandler for his help
with the text.
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