2. CONTENT
Introduction
Sources of anchorage
Classification
Anchorage loss
Use of implant or Temporary Anchorage
Device(TAD)
Types of microimplant
Indication for TAD
Sites for placement of microimplant
Size of microimplant
Direction of implant placement
3. Procedure of placement of TAD
Removal of implants
Possible complication of TAD
Anchorage planing
4. LEARNING OBJECTIVE
The student should acquire the following knowledge
during the period of training:
Extraoral and intraoral sources of anchorage
Various types of anchorage
Implants or Temporary Anchorage Devices(TAD)
Anchorage planing
Loss of anchorage
5. DEFINITION –
Nature and degree of resistance to
displacement offered by an anatomic
unit when used for the purpose of
effecting tooth movement.(Graber)
The site of delivery from which a force
is exerted. (White and Gardiner)
6. SOURCES OF ANCHORAGE
INTRAORAL SOURCES OF ANCHORAGE
1. TEETH- most frequently used anchorage units
Factors that can influence the anchorage potential of
teeth are:
i) Root Form: 3 types of cross sections of root:
a) Round- least anchorage
found in premolars
palatal root of maxillary molar
b) flat- mesiodistally flat roots can better resist tooth
movement in a mesiodistal direction than in a
labiolingual direction
7. Seen in mandibular incisors
mandibular molars
buccal roots of maxillary molars
c) Triangular- offer maximum resistance
seen in maxillary central incisors
canines
ii) Size of roots
iii) Number of roots
iv) Anatomic position of tooth- since mandibular
second premolar is located between mylohyoid and
external oblique ridge it offers increased resistance
8. v) Axial inclination of the tooth
vi) Proximal contacts and intercuspation between
teeth
vii) Ankylosed teeth
2. Alveolar bone- offers resistance to tooth movement
up to a certain amount of force exceeding which
bone remodeling occurs.
3. Basal bone- certain areas of basal bone such as
hard palate and lingual surface of anterior
mandible can be used to augment anchorage
4. Musculature – normal tonicity of facial and
masticatory muscles is important for normal
development of the dental arches
9. EXTRAORAL SOURCES OF ANCHORAGE
1. Cranium (Occipital and Parietal bones)
2. Back of the neck (Cervical region)
3. Facial bones – Frontal bone and mandibular
symphysis
11. ii. According to jaws involved
1. Intra-maxillary
2. Inter-maxillary
iii. According to site of anchorage
1. Intra-oral
2. Extra-oral
Occipital
Cervical
Facial
3. Muscular
12. iv. According to number of anchor units
1. Single or Primary
2. Compound
3. Multiple or Reinforced
13. SIMPLE ANCHORAGE
Definition: manner &
application of force – change
the axial inclination –
anchorage unit in the plane
of space in which force is
being applied
Resistance to tipping
Root surface area of
anchorage unit must be
double to that of teeth to be
moved
For example: movement of
palatally placed tooth
Lower anchorage value
14. STATIONARY ANCHORAGE
Manner and application of force is such that it tends
to displace the anchorage unit bodily in the plane of
space in which the force is being applied.
Anchorage provided by a tooth resisting bodily
movement is considerably greater than one
resisting tipping force.
15. RECIPROCAL ANCHORAGE
Resistance offered by two
malposed units when the
dissipation of equal and
opposite forces tends to
move each unit towards a
more normal occlusion.
Two teeth or two groups of
teeth of equal anchorage
value are made to move in
opposite directions.
For example: Cross- bite
correction, Closure of
midline diastema, dental
arch expansion
16. INTRA-ORAL ANCHORAGE
Teeth to be moved and anatomic areas that offer
anchorage are all within the oral-cavity
Intra-oral anatomic units- teeth, palate, lingual
Alveolar bone of mandible
18. MUSCULAR ANCHORAGE
Forces generated by muscles are used to move
teeth
For eg. Lip bumper to distalize molars.
19. INTRAMAXILLARY ANCHORAGE
Resistance units are all situated within the
same jaw.
Teeth to be moved and the anchorage units
are all situated either entirely in the
maxillary or mandibular arch.
20. INTERMAXILLARY ANCHORAGE
Units in one jaw are used to move teeth in the other
jaw.
Baker’s anchorage
Class II and class III elastics.
23. REINFORCED/MULTIPLE ANCHORAGE
More than one type of resistance unit is utilized.
Augmentation of anchorage by various means.
For example : TPA and lingual arches
extraoral forces
upper anterior inclined plane.
24. ANCHORAGE LOSS
Unwanted movement of anchor teeth.
Anchorage demand of an extraction case:
1) Max. anchorage case-not more than ¼
2) Moderate anchorage cases-1/4 to ½
3) Min. anchorage cases-more than ½
25. USE OF IMPLANTS OR TEMPORARY
ANCHORAGE DEVICE(TAD)
Also known as ortho-implant, micro-implant,
miniscrews, skeletal anchorage devices or
microscrews.
o Allows absolute anchorage.
o Mechanically retained in bone and do not
osseointegrate with the bone.
o Definition- device that is temporarily fixed to bone
for the purpose of enhancing orthodontic anchorage
either by supporting the teeth of the reactive unit
(anchorage) or by obviating the need for the
reactive unit altogether, and which is subsequently
removed after use.(Cope)
26. TYPES OF MICROIMPLANTS
According to exposure of head:
1) Open method: Head of microimplant is exposed to
oral cavity. Used where soft tissues are not
moveable.
2) Closed method: Head is embedded under soft
tissue. Used where soft tissue is moveable.
27. According to method of placing the implant:
1) Self tapping method: Tunnel is first drilled into the
bone and the implant is then tapped in. Used for
smaller diameter implants.
2) Self drilling method: Implant itself drills into the
bone. Used for larger diameter implants.
28. According to path of microimplant insertion:
1) Oblique direction: microimplant is inserted
diagonally at an angle of 30-60 degree to the long
axis of the tooth. Useed where interradicular bone
is very narrow.
2) Perpendicular: Microimplant is inserted
perpendicular to the bone surface. Used when
there is sufficient interradicular bone.
29. INDICATIONS FOR TAD
1) Posterior teeth are missing
2) Distalization of molars.
3) Intrusion of maxillary teeth.
4) Correction of anterior open bite and deep bite.
5) Retraction of anterior teeth.
6) Correction of canted occlusal planes.
7) Treatment of class III malocclusion.
30. SITES FOR PLACEMENT OF MICROIMPLANTS.
Maxillary area
1) Maxillary tuberosity
2) Infrazygomatic crest area
3) Buccally between maxillary first and second molar
4) Buccally between 6 and 5
5) Buccally between 3 and 4
6) Labially between maxillary incisors
7) Palatally between 5 and 6
8) Mid palatal area
31. Mandibular area
1) Retromolar region
2) Buccally between 6 and 7
3) Buccally between 6 and 5
4) Buccally between mandibular premolars and
canine
5) Facially in the symphyseal region
32. SIZE OF MICROIMPLANTS
Titanium-alloy miniscrew ranging from 6-12 mm in
length and 1.2 to 2 mm in diameter.
Maxilla- 7-8 mm
Mandible- 5-6 mm
Length of implant driven into bone- 4-6 mm
33. DIRECTION OF IMPLANT PLACEMENT
Due to density of cortical bone and adequate
amount of interradicular space in the mandible and
palatal region of maxillaTAD should be placed
perpendicular to bone.
In contrast, in the maxilla, the interradicular space
is very limitedand the cortical bone is not as dense.
Therefore, it is preferable to anngulate a TAD in a
diagonal directionapically to engage more cortical
bone and avoid accidental injury to the roots
34. PROCEDURE OF PLACEMENT OF TAD
IOPA or OPG- to assess inter-radicular space
available- minimum 2 mm
Minimum amount of LA given into mucosa adjacent
to implant placement site.
Pilot hole drilled with 1.2 mm drill at 600rpm to just
short of implant length.
Cooling with physiological saline solution.
Implant inserted using handpiece at 12 rpm or hand
driven with a hand driver.
35. REMOVAL OF IMPLANT
Removed with the same screw driver as used for
insertion.
Done under application of LA gel.
Removal site swabbed with 0.2% chlorhexidine.
36. POSSIBLE COMPLICATIONS OF TAD
1) Contact with adjacent roots
2) Breakage of implant
3) Damage to anatomic structures
4) Soft tissue overgrowth
5) Implant loosening- causes- poor bone quality,
excessive force application and approximation to
the root surface.
37. ANCHORAGE PLANNING
Anchorage requirement depends on the following
factors:
1) Number of teeth being moved
2) Type of teeth being moved
3) Type of tooth movement
4) Duration of tooth movement
5) Skeletal pattern
6) Occlusal interlock
38. BIBILOGRAPHY
Graber TM: Orthodontics: Principles and practice.
WB Saunders, 1988
Profitt WR: Contemporary Orthodontics, St Louis,
CV Mosby, 1986
Robert E Moyers : Hand book of Orthodontics, Year
book medical publishers, inc, 1988
Thomas M Graber, Robert L Vanarsdall:
Orthodontics current principles and techniques,
Mosby year book Inc, 1994
