Anchorage in orthodontics

1. Basics of Orthodontic
ANCHORAGE
Mahmoud Shaheen
BDs, PGDipimp, MBAAFS

2. Prepared under Supervision of
Prof. Dr. Med.Dent. Nezar Watted

3. Anchorage!!

4. Cont.
 Websters international dictionary
defines anchorage as (a secure hold
sufficient to resist a heavy pull)!!

5. DEFINITION
- Resistance to Displacement
OR
- Resistance to unwanted tooth movement
It obeys Newton's Third Law of Motion
“To every action there is an equal & opposite reaction”

6. Each orthodontic appliance consists
of two elements
1) Anchor Unit
2) Moving Unit

7. if an upper canine is being retracted, the force applied to the
tooth must be resisted by an equal and opposite force in the
other direction. This equal and opposite force is known as
anchorage.

8. Classification of anchorage:
1. According to the site: Intra oral.
Extra oral.
2. According to the jaws involved:
Intra-maxillary anchorage.
Inter-maxillary anchorage.
3. According to the manner of force application:
Simple. Stationary. Reciprocal.
4. According to number of anchor units:
simple. Compound. reinforced.

9. Intra-oral anchorage:
 Teeth: root form, number, length, inclination,
ankylosing, position.
 alveolar bone.
 Basal bone (Nance P. arch button).
 Musculature: lip bumper.

10. Anchorage Value

11.  Cervical: Low pull Head gear
 Occipital: Medial pull Head gear
 Cranial: High pull Head gear
 Facial: Face mask
Extra-oral anchorage:

12. High pull Head gear
Low pull Head gear
Straight Head gear

13. Cervical Headgear
Face mask

14.  Intra-maxillary (Anchorage established in same
jaw, (TPA)
 Inter-maxillary (Anchorage distributed to both
jaws, e.g. Inter-maxillary elastics)
According to Jaw Involved

15. According to manner of force
application:
1. Simple anchorage: Resistance to tipping

16. Cont.
2. Stationary anchorage: resistance to bodily
movement.

17. Cont.
3. Reciprocal anchorage: two or more teeth
moving in opposite direction, (Resistance to
each other is equal and opposite).

18. According to Number of Units:
1. Single or Primary Anchorage:
(Anchorage involving one teeth)

19. Cont.
2. Compound Anchorage:
(Anchorage involving two or more teeth)

20. Cont.
3. Reinforced Anchorage:
(Addition of anchorage savers such as; TPA,
head gear)

21. Reinforced Anchorage:
 When anchorage is obtained from
more than one type of resistant unit,
it is called reinforced anchorage.
 Examples:
1. Extra-oral head gears.
2. Transpalatal arch.
3. Implant anchorage (Mini implants,
Micro implants, Mini screws, TADS).

22. Cont.
 Implant anchorage, nowadays, mini implants
are used to provide excellent anchorage for
demanding cases. They can be placed in
different areas like the hard palate, between
upper premolars, retro molar area, etc, to
reinforce the anchorage.
 Implant anchorage is an example of skeletal
anchorage or absolute anchorage which is also
provided by an ankylosed tooth.

23. E.g.: Watted Micro implants
Wurzburg -Germany

26. Factors affecting anchorage:
 Biological factors:
 Anchorage value of the tooth; depends on size
& number of teeth and their root surface area.
 Axial inclination of teeth; disto-axial inclination
of the anchor teeth increases its anchorage.
 Avoid early extraction & delay in start of
mechanics.
 Optimum force and differential force system
use.
 Abnormal habits will reduce anchorage.(Thumb
Sucking).

27. Cont.
 Mechanical factors:
 Friction; most imp factor, it is very high with
nitinol wires and ceramic brackets. It is low in
Stainless steel wires and brackets. High friction
leads to anchorage loss.
 Type of tooth movement; we need more
anchorage if we want bodily movement of teeth.
 Retraction mechanics; free sliding, frictionless
mechanics help to protect anchorage.
 Anchorage augmenters or savers; TPA, inclined
plane, head gear, implant etc.

28.  Anchorage Loss
Unintentional movement of anchor unit
 Anchorage Burn
Intentional movement of anchor unit

29. Anchorage loss:
 The unwanted movement of the anchor teeth is
called anchorage loss.
 It is any movement of the anchor teeth during
the desired movement of other teeth.
 If deliberately lost by orthodontist, the
anchorage loss is sometimes termed “burning”
of the anchorage.

30. Cont.
 Signs of anchorage loss are:
 Mesial movement of the anchor molars.
 Closure of extraction space by movement of
posteriors.
 Proclination of anterior teeth.
 Spacing of teeth.
 Increase in overjet.
 Change in molar relation. Class I may change
to class II.

31. Anchorage Demand:
1. Maximum anchorage cases:
 not more than 1/4th of the extraction space
should be lost by movement of the anchor
molars.
 Augmentation of the anchorage is needed in
such cases.
 Anchorage demand is High.
 This type of anchorage is called type A anchorage.

32. Cont.
2. Moderate Anchorage cases:
 The anchor teeth may be permitted to move
forward into ¼ up to ½ of the extraction space.
 Anchorage demand is moderate.
 This type of anchorage is called type B
anchorage.

33. Cont.
3. Minimal anchorage cases:
 In these cases, more than half of the extraction
space can be lost deliberately.
 Termed as “burning” of anchorage.
 Anchorage demand is very low.
 This type is called type C anchorage.

34. Cont.
4. Absolute anchorage cases.
(Absolutely no movement of anchor unit e.g.
Implants , Ankylosed T.)

35. Key points:
 Orthodontic anchorage is the resistance to
unwanted tooth movement.
 The forces needed to orthodontically move a
tooth will vary depending on the type of tooth,
its periodontal condition, the distance of
movement planned, as well as the type of
orthodontic tooth movement desired.
 Goals of anchorage management are to
maximize desired tooth movement and
minimize unwanted tooth movement.

36. Cont.
 Anchorage is not just an anteroposterior
phenomenon; unwanted tooth movements can
also occur in the vertical and transverse
dimensions.
 Anchorage control needs to be continually
monitored during treatment to obtain the
optimum aesthetic and occlusal result. The
earlier any problems with anchorage control
are identified, the less undesirable tooth
movement will have occurred and the more
scope there there will be for correction.