ANCHORAGE IN ORTHODONTICS: DEFINITION, CLASSIFICATION, PLANNING AND LOSS

ANCHORAG
E
INDIAN DENTAL ACADEMY

Leader in continuing dental education
www.indiandentalacademy.com


INDEX











DEFINITION
CLASSIFICATION
FACTORS AFFECTIONG ANCHORAGE
SOURCES OF ANCHORAGE
ANCHORAGE PLANNING
DIFFERENT ANCHORAGES
ANCHORAGE LAOSS & DEMAND
ADVANCEMENT IN ANCHORAGE
CONCLUSION
REFERENCES


INTRODUCTION




ANCHORAGE = RESISTANCE TO UNWANTED
TOOTH MOVEMENT.



ANCHORAGE UNITS : The areas or units which
provide this undesirable movement.


DE INIT ION
F
IT


THE SITE OF DELIVERY FROM WHICH
FORCE IS EXERTED
- white n gardner
The nature and degree of resistance to
displacement offered by an anatomic unit
when used for the purpose of affecting
tooth movement
- GRABER



CLASSIFICATION



1.
2.
3.

1.
2.

Acc. to manner of the force application as:
Simple
Stationary
Reciprocal
Acc. to the jaws involved as :
Intra maxillary
Inter maxillary



1.
2.
3.

1.
2.
3.

Acc. to the site of anchorage
Intra oral
Extra oral
Muscular
Acc.to the no. of anchorage units as :
Simple
Compound
Reinforced


1.
2.
3.
4.
5.
6.

Acc. To white n gardner
Simple
Stationary
Reciprocal
Reinforced
Inter maxillary
Extra oral


Factors affecting
anchorage


1.
2.






Teeth
Root forms

Round – resistance is same in any direction
Flat – resist tooth movement in M-D direction eg. mand.
Incisors & molars , buccal roots of max. molars ( tripod
arrangement of roots )
Triangular – offers greater resistance to movement. Eg.
Maxillary canine & lateral incisor


1.
2.
3.

4.

5.

Size n no. of roots – large surface area & multirooted
teeth > resistance
Root length – deeper the root embeded > resistance
Position of tooth in the dental arch – eg. Mandi. 2 nd molar
is located bt. Two ridges of basal bone , so offer more
resistance to bodily movement
Inclination of tooth – axial inclination is in opposite
direction to force , greater resistance

Mutual support

1.

Basal bone – eg.hard
palate & lingual surface
of the mandible in
anterior region.

2.

The musculature –
Hypotonic m. - Flaring &
spacing
Hypertonic m. - Collapse
of the teeth lingually

eg.Nance palatal button
( use of hard palate to
provide resistance to
mesial movement of
max. molar


SOURCES OF ANCHORAGE



1.
2.
3.
4.

1.
2.
3.
4.


INTRA –ORAL :
Individual teeth
Multiple tooth units
Encasement (eg.Inclined planes)
Occluding teeth
OTHERS :
Holding Arches
Basal bone
Neck cranium
Occipital region
MUSCULATURE : lip bumper


ANCHORAGE
PLANNING


Depends on : 1.
2.
3.
4.
5.

The number of teeth to be moved
The type of teeth to be moved
Type of tooth movement
Periodontal condition
Duration of tooth movement


INTRA
MAXILLARY
ANCHORAGE


Within the same jaw ( either maxilla or
mandible )
 Eg.Elastic chains are
used to retract the
anterior segment
using the posterior
teeth as anchorage
unit.



Sub- divisions
1.
2.
3.

Simple
Stationary
Reciprocal


INTER MAXILLARY
ANCHORAGE


Also called

“BAKER’S ANCHORAGE”



When the anchorage units situated in the one
jaw are used to provide the force required to
move teeth in the opposing jaw.



SUB DIVISION :
Simple
Staionary
Reciprocal

1.
2.
3.




Eg. When class II elastics are used to
retract the maxillary anteriors , the
anchorage units are situated in the
mandibular arch.




CLASS III INTER MAXILLARY ELASTICS


SIMPLE
ANCHORAGE






When the manner & application of force is
such that it tends to change the axial
inclination of the tooth or teeth that form the
anchorage unit in the plane of the space in
which the force is applied.
Simple anchorage is obtained by engaging
a greater number of teeth than are to be
moved

NT: The root surface area of the anchorage unit
should be at least double that of the units to be
moved.
eg.

Anterior retraction with the
help of a HAWLEY’S
appliance

The movement of a single
tooth using a screw
appliance

STATIONARY
ANCHORAGE




When the application of force tends to displace
the anchorage unit bodily in the plane of space in
which force is being applied



The anchorage potential of teeth being moved
bodily is considerably greater as compare to
teeth being moved using a tipping force.




Mandibular molars are bodily pitted against
the tipping forces of the maxillary anteriors.


RECIPROCAL
ANCHORAGE








When two teeth or two sets of teeth move to an
equal extend in an opposite direction .
Here the root surface area of the anchorage unit
is equal to that of the teeth to be moved.
The effect of the forces exerted is equal.


• Cross Elastic To Correct
Molar Cross-bite


Ni-Ti

Molar
Rotator



Arch expansion using a midline screw


SINGLE OR PRIMARY ANCHORAGE


The resistance provided by single tooth
with greater alveolar support is used to
move another tooth with lesser alveolar
support.



Eg. Molar being used to retract a pre
molar

COMPOUND ANCHORAGE


The resistance is provided by more than one
tooth with greater support is used to move
teeth with less support.



Eg. Retracting incisors using loop mechanics


REINFORCED
ANCHORAGE




The anchorage units are reinforced by the
use of more than one type of resistance
units.




Anterior inclined plane
Exerts a backward
pull on the maxillary
appliance through the
mandible




SVED BITE PLANE :

Prevent from being
inclined labially.




A rigid labial bow :

To engage labial surface
of the incisor at the
junction of cervical &
incisal third of each
crown.




Banding of 2nd molar
for the retraction of
permanent canine


EXTRA ORAL
ANCHORAGE




The extra oral structure most commonly
used are :

1.

Cervical region
The occiput
The forehead
The chin

2.
3.
4.


Extra oral forces to augment
anchorage


Advantage


The anchorage unit is far away from the
actual site where the movement is taking
place, so less chances of any change in
the anchorage units


Disadvantage





Lack of patient’s co- operation
Anchorage assembly is bulky & externally
visible
Decrease in the number of hours for which the
anchorage assembly is worn, so affects quality
of result achieved


MUSCULAR
ANCHORAGE







Peri oral musculature is not so strong but also
resilient.
The forces generated by the musculature
sometimes used to bring about tooth
movement.
eg.Lip bumper appliance
(to distalize mandibular
1st molars)


ANCHORAGE LOSS


It is the movement of the reaction unit or
the anchor unit instead of the teeth to be
moved.


ANCHORAGE DEMAND


Depending on anchorage loss : -

1.

Maximum anchorage case
Moderate anchorage case
Minimum anchorage case

2.
3.


Maximum anchorage cases


Anchorage demand is
very high



Not more than ¼ th of
the extraction space
should be lost by
forward movement of
the anchor teeth


Moderate anchorage cases


Anchor teeth can be
permitted to move
forward into ¼ th to ½
of the extraction
space.


Minimum anchorage cases


Anchorage demand is
very low


ADVANCEMENT
IN
ANCHORAGE


REFERENCES






Contemporary Orthodontics –
(2nd edition)
BY WILLIUM R. PROFIT
Text book of orthodontics –
(1st edition)
BY GURKEERAT SINGH
Orthodontics principles and practice (3rd edition)
BY GRABER
Textbook of orthodontics –
( 3rd edition)
BY M.S RANI
Internet – (www.google.com)
(http:www.miniimplantanchorage.com)


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ANCHORAGE IN ORTHODONTICS: DEFINITION, CLASSIFICATION, PLANNING AND LOSS

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ANCHORAGE IN ORTHODONTICS: DEFINITION, CLASSIFICATION, PLANNING AND LOSS