Temporary anchorage devices in orthodontics

1. Temporary anchorage devices
(TADs) in orthodontics

2. Introduction:
• Anchorage control is one of the most
important aspects of orthodontic
treatment. The success of orthodontic
treatment depends on the anchorage
protocol planned for a particular case .
(1)The current perspective of implants in
orthodontics is mainly being investigated
with the use of TAD which are relatively
new arnamentarium in clinical practice.(2)

3. History
• Gainforth and Higly(1945)-studied
effectiveness of vitallium screws and
stainless steel wires in the mandibles of
dogs to retract the maxillary canine.
• Branemark and coworkers (1964,1969)-
worked on concept of Osseo integration
and use of titanium implants to replace
missing tooth.

4. Cont.
• Linkow(1969)-First reported a patient
treatment with the use of Osseo
integration implant for both restorative and
orthodontic purpose.
• Creekmore and Eklund (1983)- used
surgical vitallium bone screw just bellow
the anterior nasal spine to treat deep
overbite and it was 1st
clinical report on the
use of TAD.

5. Cont.
• Kanomi (1997)-first reported the clinical
use of mini-implants for orthodontic
anchorage. He implanted in the alveolar
bone between the root apices of
mandibular incisors and did intrusion of
mandibular incisors.(2)

6. Classification
1. According to the shape and size:
I) Conical (Cylindrical)
a) Miniscrew Implants
b) Palatal Implants
c) Prosthodontic Implants
II) Mini plate Implants
III) Disc Implants (Onplants)
2. According to Implant bone contact:
I) Osteointegrated
II) Non-osteointegrated
3. According to the application:
I ) Used only for orthodontic purposes. (Orthodontic Implants) or TAD
(temporary anchorage devices)
I I ) Used for prosthodontic and
orthodontic purposes.(1)

7. Cont.
• TADs can also be grouped based on types
of anchorage device used on the following
basis-
1.Endosseous implants
2.Surgical miniplates
3.Miniscrew implants(2)

8. Endosseous:
-These Osseo integrated are modified form
of conventional dental implants.
-Placed in palate,retromolar area,area of
absent or missing teeth.
-can withstand more force than
mechanically retentive implants.
-Drawback-limitation in the area of
placement,

9. Cont.
Because of large size
-extensive surgical procedure
-difficulty in removal
-costly

10. Surgical miniplates
1.Modified or even conventional L or T
shaped surgical titanium mini plates
2.Placed in thick cortex similar to -zygomatic
region -buccal cortex of mandible.
3.Use-en mass distalization of lower arch in
class-3,maxillary intrution of buccal
segment in openbite,en-mass maxillary
molar distalization

11. Miniscrew implants
1.Mechanically retentive miniscrew implants
used for short period.
2.The tiny size( diameter 1.2-1.7mm and
length 4 to 12mm) screws are versatile in
site of placement most commonly inter –
radicular bone between teeth.

12. Classification of miniscrew of
implants
1.Based on composition
Biotorant
Stainless steel
Chromium-cobalt alloy
Bioinert
Titanium
Carbon
Bioactive
Vetaroceramic
Apatite hydrxi
Ceramic oxidised aluminium
Bioresorbable
polyactide

13. Cont.
2.Based on the site of placement
Buccal
Palatal
3.Based on technique of placement
Self-drilling
Tapping
4.Based on shape
Cylindrical
Tapered
Combination

14. Cont.
5.Based on size
Lenth4-12mm(small,medium,large)
length1.15-2.5mm(small,medium,large)
6.Based on head type
Small
Long
Circle
Fixation
Bracket
Hook

15. Design and parts
Conventional orthodontic miniscrew
implants are made of bioinert pure
titanium or titanium alloy or titanium
coated stainless steel. Among these
titanium alloy (Ti6Al4V) is the most
commonly used materials for its
biocompatibility and high strength property
that it can withstand torque insertion and
stresses of orthodontic loading. screws
are designed to withstand up to 500g
force.

16. Cont.
Mini screws are designed to be
mechanically retained in the bone
because they should not Osseo integrate
for the ease of subsequent removal
following completion of their use. They
should be preferably self drilling to
placement.(2)

17. Parts
1.Head:
It is the portion exposed in oral cavity.It
provides attachments for spring and
elastics.It has a screw driver slot or a
specific shape to engage the miniscrew
driver for implant placement. Solid head
with a screw driver slot is recommended
for easy insertion and removal.

18. Cont.
2.Neck:
Screw neck or Transmucosal portion that
passes through the mucosa. The neck
connect the main screw with the head
remains in contact with mucosa. The neck
should be smooth and well polished to
facilitate contact with mucosa and
discourage plaque accumulation arround
the neck.

19. Cont.
3.Screw:
It embeds into the cortical and medulary
bone to provide retention.The screws are
designed self drilling and self tapping. self
drilling is one that does not require a pilot
hole and has either a sharp tapered apex
to allow placement or a notch in the tip to
drill through the cortex.

20. Cont.
self tapping mimiscrews are able to create their
own threads as they advance.These are two
type
thread forming-compress the bone around the
thread as the miniscrew advance.
thread cutting- either a notch at the tip parellal
to the long axis or a sharpened thread that
actually cuts threads into the bone as the
miniscrew is inserted.

21. Indication of TAD
1.As maximum anchorage requirements in
retraction such as high angle bimaxillary
protrusion.
2.In case of missing teeth eg.1st
molar it can
provide anchorages well as manage the space.
3.To achieve difficult tooth movements-
- anterior and posterior intrusion
-en mass desalination of upper and lower
arches.

22. Cont.
- Molar up righting
- Molar distalisation
4.In adjunctive adult orthodontics for difficult
tooth movement.
5.Implants are even used for attaching
orthopaedic forces to jaws when there is
lack of anchorage units.

23. Limitations:
1.Orthodontic miniscrew implants are not
indicated in the patient having systemic
problems that affect bone metabolism and
major medically compromising condition.
2.Patients younger than 12 years who have
not yet completed skeletal growth.
3.In heavy smokers and patient with bone
metabolic disorders.

24. Cont.
4.These should not be placed in the areas of bone
remodeling such as a healing socket or near a
deciduous tooth.
5.Thin cortical bone limits the use of miniscrew
implants. Because miniscrew implants are
mechanically retained ,loosening of screw can
develop as a result of thin cortical bone, if
thinner than 0.5 mm and also if bone density of
trabecular bone is low.

25. Cont.
6.Clinicians skill.
7. Ethical issue

26. Safe zone for miniscrew implants
1.Posterior region:
Most common sites are inter radicular bone
between 2nd
premolar and 1st
molar and between
1st
and 2nd
molar.In palate inter radicular bone
between 2nd
premolar and 1st
molar and between
1st
molar and 2nd
molar. In posterior palate should
be placed mesially to the 2nd
molar to avoid
damage of greater palatine artery and the
palatine nerve.

27. Cont.
2.Anterior region:
In maxilla between central and lateral incisors
at 6 mm above CEJ.A single ms can placed in
maxilla in the midline below anterior nasal spine.
In mandible between lateral incisor and canine.
For the anterior palate, ms length is
determined by the bone depth assessed in
cephalogram. The anteroposterior location of ms
are planed to optimize the available bone.In
paramedian portion of palate ,6-9 mm posterior
to the incisive foramen 3-6 mm laterally.

28. Cont.
3.Other location:
mandibular symphysis, retromolar
infrazygomatic and maxillary tuberosity
areas.(2)

29. Miniscrews placement protocols
1.Case selection:
Routine orthodontic records,intraoral
radiograph of the miniscrew site to asses the
bone width. Crestal bone loss,root lenth
,angulation of roots.Assesment of bone density
required on if doubt exist on quality of bone on
routine X-rays or medical history or history of
medication which can alter bone
metabolism.Bone density value obtained through
CT scan or cone beam computed
tomography(CBCT).

30. Cont.
2. Miniscrew selection:
Selection of miniscrew size is governed
by the anatomical limits of its
placement.longer implants are used in
retromolar area while conventional in inter
radicular bone in maxilla and mandible.
We have used 1.4-1.5 mm in the length
of7-8 mm length inter radicular area of
maxilla and mandible.

31. Cont.
Other considerations:
A miniscrew intended to be placed between
roots should be narrow enough to get
accommodated and should have at least 1 mm
bone around its maximum diameter.
Miniscrew implants having 1.2-1.3 mm
diameter can withstand 500g force where
orthodontic application need forces of less than
300g.

32. Surgical procedure:
Following an accurate clinical assessment
and observations, the patient is advised to
start suitable antibiotic(250 mg amoxicillin)
on the night before surgery.The mouth is
thoroughly cleaned .
1. patient rinse with 10ml of o.12%
chlorhexidine gluconate mouth wash for 1
minute.
2.Local aneasthesia

33. Cont.
3. Miniscrew is then carefully driven at
predetermined site at the desired angle
using appropriate driver.(45-50 to long
axis in maxilla and 10-30 reduce in
posterior mandible).
4. Post operative care. Careful review of
unusual signs of inflammation and check
on mobility of implant.

34. Removal:
• Miniscrew can be removed under topical
anaesthesia with the instruments used for
driving followed by anticlockwise turns by
holding with tweesers.

35. Safe zone

36. Safe zone

37. Refference
1.Temporary anchorage device insertion
variables: effects on retention
Joseph S. Petreya; Marnie M. Saundersb;
G. Thomas Kluemperc;
Larry L. Cunninghamd; Cynthia S. Beemane
ABS.Angle orthodontist.vol 80:no 04;2010
2.Om Prakash Kharbanda .Orthodontics
diagnosis and management of
malocclusion.