This document discusses the use of temporary anchorage devices (TADs) such as mini-screws and mini-plates for orthodontic anchorage. It provides information on various TAD systems including the Aarhus Anchorage System, IMTEC Mini Ortho Implants, and Spider Screw Anchorage System. The document discusses TAD placement locations, surgical procedures, orthodontic mechanics, advantages, and potential complications. It emphasizes the importance of treatment planning for anchorage when using TAD-assisted mechanics.
4.
The Aarhus Anchorage System
IMTEC Mini Ortho Implants
The Spider Screw Anchorage System
Biomechanical considerations
conclusion
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5.
Adult patients have sought orthodontic
treatment, often referred by periodontists,
restorative dentists, or prosthodontists.
The long clinical crowns seen in these
patients are the result of super eruption in
addition to marginal bone loss, resulting in
bite deepening.
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6.
The bone quality in the infrazygomatic crest
is generally good and proves sufficient
anchorage for the maintenance of a ligature
wire during loading.
MELSEN and colleagues described the
insertion of a surgical wire through the
infrazygomatic arch.
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7.
A transmucosal incision, approximately 1 cm
long, was made along the superior aspect of
the infrazygomatic crest.
A horizontal bony canal was drilled through
the zygomatic process approximately 1 cm
lateral to the alveolar process.
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9.
A double twisted 0.012-inch stainless steel
wire was inserted through the canal.
To protect the soft tissues, the twisted part of
the wire was covered with a polyethylene
tube.
Once the incision was closed, the surgical
wire was bent and adapted so that the ideal
point of force application could be
established.
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10.
The replacement of the ligature with a screw
seemed a logical progression since it offered
better stability and made the surgical
placement simpler.
COSTA and colleagues described a miniscrew
with a head that imitated a bracket.
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12.
The Aarhus anchorage system is available in
either 1.5 or 2mm diameters.
To evaluate the load transfer from the
miniscrew to the surrounding bone— two
different three dimensional finite element
models (FEM) were developed.
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13.
The stress levels were higher in the cortical
bone than in the underlying trabecular bone.
The thickness of the cortical bone determines
the overall load transfer and that the density
of trabecular bone plays only a minor role.
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14.
Areas suitable for insertion were established
by analyzing a series of dry skulls.
The areas recommended in the maxilla are
the infrazygomatic crest, the alveolar
process, the palate, the infranasal spine, and
the retromolar area.
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The areas recommended in the mandible are
the retromolar area, the alveolar process, and
the symphysis.
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16.
A periapical radiograph taken with an acrylic
or putty based template serves as a guideline
for establishing the exact height and
orientation of the miniscrew.
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18.
In the case of thick cortical bone, a 2-3mm
incision is made and a pilot hole prepared
with a drill 0.3 mm smaller in diameter than
the miniscrew. The miniscrew is then
manually inserted with a custom screwdriver.
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19. Complications–
Complications related to the use of
miniscrews are rare and can be classified into
three groups:
Complications During Insertion
Complications During the Loading
Period
Complications at Removal
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20. Complications During Insertion:
Initial lack of stability due to inadequate
thickness of the cortical bone.
Miniscrew insertion in the periodontal
ligament or tooth root.
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21. Complications During the Loading Period:
The miniscrew may become loose.
The loosening may be caused by either local
inflammation or local bone remodeling.
Hypertrophy of the mucosa adjacent to a
miniscrew may develop.
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22. Complications at Removal:
The miniscrew cannot be removed.
If this does occur, then the miniscrew can be
removed with a trephine.
The miniscrew could fracture on removal.
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23.
The Ortho Implant was recently developed
from IMTECs established, Food and Drug
Administration (FDA)-approved mini implant
system (Sendax Mini Dental Implant).
The implant was modified at the head to
provide orthodontic force systems the benefit
of a hole to which an appliance may be
attached.
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25.
The implants are available in 6, 8,
and 10mm lengths.
The implant is made from a
titanium alloy (Ti-6Al-4V) that
research has shown to be 2.5 times
stronger than commercially pure
titanium.
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26.
Indicated for correction of open/deep bite
(intrusion of over erupted teeth).
Intrusive molar uprighting
Mesiodistal translation along the arch without
taxing the anchorage of remaining teeth.
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27.
This mechanotherapy is especially useful in
patients with high mandibular plane angles or
patients with a clockwise rotational growth
tendency.
Mini implant anchorage is an asset in the
treatment planning of maximum anchorage
retraction cases.
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28. Surgical Procedure
Identification of the exact location.
When an intra or interradicular application is
desired a brass wire separator can be used as
a guide.
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29.
The wire is placed between the adjacent
teeth. The brass wire is twisted, directed
gingivally, and cut so that it terminates at the
prescribed placement location.
A periapical radiograph is then exposed to
verify that the prescribed placement will not
interfere with the roots of the teeth.
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30. Ortho Implant placement procedure without flap
reflection. (A) Soft tissue punch. (B) Pilot drill. (C) Ortho
Implant placement with straight driver.
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31. Surgical Ortho Implant
placement with flap
reflection. (A) Incision.
(B) Pilot drill. (C) Ortho
Implant placement with
straight driver. (D) Ortho
Implant in place.
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32. Orthodontic Mechanics:
When an Ortho Implant is used to address
vertical elements of a malocclusion, it should
be placed as deep in the vestibule as is
reasonably attainable.
For typical anterior openbite closure or molar
intrusion, the implants are commonly placed
laterally in the alveolus between the 1st and
2nd molar
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33.
The implant can be angled at 10° to 20° to the
long axis of the tooth, such angulation
permits the deeper vestibular placement of
the implant.
In a maximum anchorage case, the Implant
can be placed laterally in the alveolar ridge
mesial to the 1st molar.
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35.
Complications predominately lie in the
potential for iatrogenic placement and poor
soft tissue response.
Soft tissue has the potential to grow over an
exposed implant head—placement of healing
cap.
Placing the implant into an adjacent tooth
root.
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37.
The Spider Screw (HDC Company, Sarcedo,
Italy) is used as a noncooperation based
anchorage system.
It is a self-tapping, commercially pure
titanium miniscrew.
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38.
Used in clinical situations involving mutilated
dentitions, poor cooperation, or extraction
cases requiring maximum anchorage.
This system is available in either 1.5 or 2mm
diameters. The 1.5mm diameter screw comes
in 6, 8, or10mm lengths, while the 2mm
diameter screw comes in 7, 9, or 11mm
lengths.
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39.
Available in three different transmucosal
designs to accommodate the soft tissues
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41. Sites of choice include the :
Maxillary tuberosity
The mandibular retromolar area
Edentulous areas
Interdental sites
The palatal vault and
The alveolar processes above the root apices
in the anterior region.
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42. Surgical Procedure:
The surgical armamentarium includes a low
speed contra angle hand piece, a bur with a
depth stop, and a hand screwdriver.
A site locator can be fabricated from resin
and orthodontic wire and utilized to
determine the insertion position of the screw
in the bone.
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43.
Long cone radiographs are taken to visualize
the site locator relative to the delicate
anatomical structures.
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45. Orthodontic Mechanics:
Miniscrew anchorage can be direct or
indirect.
There is a tendency for buccal inclination of
the clinical crowns as intrusion is attempted.
Control can be achieved by torquing
archwires or with transpalatal bars.
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46. Torque possibilities with Spider Screw. (A) Buccal
tipping during intrusion. (B) Pure intrusion using
buccal and lingual screws.
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47. Complications:
Inflammation of the peri-implant tissues,
especially in areas of frenum tissue or muscle
tissue.
These problems can be controlled with
proper oral hygiene and topical application of
a 0.2% chlorhexidine rinse.
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48. Factors influencing the stability of the titanium
screw:
Screw diameter
The second is peri-implant soft tissue
inflammation
The third is bone quality.
MIYAKAWA S, et al: AJO DO124:373-378, 2003
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49.
The use of miniscrews for anchorage
reinforcement produces somewhat different
mechanics.
The force used during retraction is not
reciprocal, either the entire arch or the
anterior segment will rotate around the
center of rotation.
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51.
In cases of severe
protrusion, where
absolute anchorage is
required in both arches,
these mechanics can
produce posterior open
bite and deep overbite.
The use of precurved
archwires will result in
an even stronger
intrusive force on the
posterior segment.
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52.
One approach is to lengthen the archwire
hook and raise the miniscrew insertion point
to redirect the vector of retraction force, so
that it passes through the center of resistance
of the anterior segment.
This is located between the lateral incisor and
canine roots, 6.76mm above the cervical
area, or at the level of the root tip.
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54.
MELSEN and colleagues recommended that
the archwire hook extend 10mm from the
main archwire, but anatomical limitations
usually make this impractical.
Elastomeric chain or coil springs positioned
above the bracket level may impinge on the
soft tissue because of archwire curvature.
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55.
It is difficult to
place the miniscrew
high enough.
Insertion in the
mobile mucosa
increases the risk
of inflammation
around the
miniscrew and may
lead to failure
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56.
Light ‘L’ inter-maxillary elastics, worn only at
night, can prevent posterior open bite
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57.
In patients with gummy smiles or other
factors favoring intrusion of an entire arch,
more vertical retraction forces can be used to
prevent occlusal plane rotation.
Occlusally directed archwire hooks should be
placed posterior to the canines.
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59.
Occlusal plane rotation due to forces of
occlusion can be prevented by bonding
anterior biteplanes to the lingual surfaces of
the anterior teeth at the beginning of
retraction.
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61.
In a patient with a gummy smile or over
erupted upper incisors, additional miniscrews
can be placed in the upper anterior region to
produce a vector of force that counteracts
occlusal plane rotation and preserves anterior
torque.
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62.
Mini-implant TADs are an excellent adjunct
to provide stable, bone based anchorage for
the application of orthodontic biomechanical
force systems.
Many different orthodontic mechanics can
incorporate the stable Implant as anchorage
in treating a given malocclusion.
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63.
In many cases, the successful outcome of
the treatment depends on treatment
planning.
In any mechanics, anchorage should be
planned and taken care of from the first day
of treatment.
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64.
Applications of Orthodontic Mini-Implants—
Jong Suk Lee, Jung Kim, Chel Park & Vanarsdall
Temporary Anchorage Devices in Orthodontics:
A Paradigm Shift-Jason B. Cope
Intraoral Hard and Soft Tissue Depths for
Temporary Anchorage Devices- Antonio Costa,
Giulio Pasta, And Giovanni Bergamaschi
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65.
Miniscrew Implants: The Aarhus Anchorage
System-Birte Melsen and Carlalberta Verna
Miniscrew Implants: IMTEC Mini Ortho
Implants-Robert Herman and Jason B. Cope
Miniscrew Implants: The Spider Screw
Anchorage System-B. Giuliano Maino, Paola
Mura, and John Bednar
[SEMINARS
IN ORTHODONTICS]
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66.
MIYAKAWA S, et al: Factors associated with
the stability of titanium screws placed in the
posterior region for orthodontic anchorage.
AJO DO124:373-378, 2003
Biomechanical considerations in treatment
with miniscrew anchorageMIN-HO JUNG, TAE-WOO KIM JCO FEB. 2008
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