Anchorage in orthodontics /certified fixed orthodontic courses by Indian dental academy

ANCHORAGE

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In simple terms anchorage in orthodontics
is defined as resistance to unwanted tooth
movement.

Angle stated that there were many means for
obtaining anchorage, including the tooth themselves
and sources external to the teeth. He classified
anchorage as simple , stationary, reciprocal, inter
maxillary and occipital.


Given Angle’s insistence on expansion of arches
rather than extraction to deal with crowding
problems, it is ironic that his edgewise appliance
finally provided the control for root position
necessary for successful extraction treatment.

One of Angle’s last student, Charles Tweed,
adapted the edgewise appliance for extraction
treatment. Tweed placed tip back bends in the
lower arch to vary the amount of distoaxial
inclination of the lower posterior teeth. The
amount of distal tip varied depending on the
severity of malocclusion.

When anchorage preparation as advocated by
Tweed was used with standard edgewise appliance the
tip, torque and offset bends had to be placed in each
edgewise arch. The bends were then duplicated or
increased in the successive arches as the case
progressed.

Reed Holdaway in 1952 described pre-
angulation of the edgewise appliance in mandibular
buccal segments as a method of setting up posterior
anchorage units into tipped back or anchorage
prepared positions.


Graber: defines anchorage as the nature and degree
of resistance to displacement offered by an anatomical
unit when used for purpose of effecting tooth movement.

Bennett and McLaughlin: emphasized the need
to consider anchorage in all the three planes of space
i.e., horizontal, vertical and lateral (transverse).

White & Gardiner: it is the site of delivery from
which a force is exerted.

Horizontally anchorage control means limiting
the mesial movement of the posterior segment
while encouraging the distal movement of anterior
segment.

Vertically, anchorage control involves the
limitation of vertical skeletal and dental
development in the posterior segment and
limitation or vertical eruption of, or even intrusion
of anterior segments.

In transverse plane It comprises of the
maintenance of expansion procedures, primarily in
upper arch, and the avoidance of tipping or
extrusion of posterior teeth during expansion.

Sources of Anchorage:
(i)extra-oral
(ii) intra-oral
Extra-oral anchorage is the anchorage in which one
of the anchorage unit is situated outside the oral
cavity . Extra-oral anchorage can be further
classified as :
 Cervical
 Cranial
o Occipital
o parietal
 Facial eg. Delaire Facemask
Intra-oral anchorage : It is the anchorage in
which the resistance units are all situated
within thewww.indiandentalacademy.com
oral cavity e.g., teeth, palate,
muscular forces, inclined planes of teeth.

Classification of anchorage: Acc to Moyers
(i)Dep. On manner of force application:
•Simple
•Stationary
•Reciprocal

(ii)Dep. On jaws involved:
•Intermaxillary
•Intramaxillary

(iii) Dep. on site of anchorage:

•Intra oral
•Extra oral
•Muscular

(iv) Dep. on no. of anchor units:

•Single / primary
•Compound
•Multiple/ reinforced

1.Natural anchorage
It comes from any resistance afforded within the arch
according to the application of forces between any given teeth
or group of teeth.
Simple Anchorage :
• Dental anchorage in which the manner and application of force
tends to displace or change axial inclination of the tooth or teeth
that form the anchorage unit in the plane of space in which the
force is being applied.
• In other words resistance of anchorage unit to tipping is utilized
to move another tooth or teeth.

Compound Anchorage :
• Here anchorage www.indiandentalacademy.com
is provided by more than one tooth with
greater support is used to move teeth with lesser support.

Reciprocal / Multiple anchorage :
It involves pitting of two teeth
or two groups of teeth of equal
anchorage value against each other
to produce reciprocal tooth
movement.
• Eg: closing of diastemas: two
central incisors are pitted against each
other.


Stationary Anchorage :
Dental anchorage in which the manner
and application of force tend to displace the
anchorage unit bodily in the plane of space in
which the force is being applied is termed
stationary anchorage (Graber).


2. Reinforced Anchorage :
• It involves reinforcing the
anchorage or resistance area
either by adding more resistance
units or by the use of various
adjuncts.
• A simple way of reinforcing
anchorage is to band the second
molars.
• Various other ways
include, the use of T.P.A., Nance
holding arch, lower lingual arch.
• Tissue anchorage such as
obtained by lip bumper can be
efficiently used to distalize molars.

• This is obtained by
various means
namely:
1.Extra oral force to
augment anchorage
2.Upper anterior
inclined plane &
SWED APPLIANCE
3.Trans palatal arch


3. Prepared Anchorage
Prepared anchorage pre sets the teeth into
disto-axial inclination, greatly increasing their
resistance to displacement. This method is very
effective for controlling anchorage, especially
when anchorage is critical.

4. Active root thrust :
This concept was put forward by Dr. Calvin
Case in 1908. It involves building bodily
resistance into the anchor area through the use
of extensions fixed to the bands of the molar
teeth. www.indiandentalacademy.com

Cortical anchorage :
 The cortical bone is more resistant to resorption
than the medullary bone. The cortical anchorage
concept makes use of this.
 Rickett’s advocated torquing the roots of buccal
teeth outwards against the cortical plate as a way to
inhibit their mesial movement.
 Torquing movements are limited by facial and
lingual cortical plates. If a root is persistently forced
against the cortical plate, tooth movement is greatly
slowed, root resorption is likely and eventual penetration
of cortical bone may sometimes occur.

Graber has classified anchorage as intramaxillary
anchorage and intermaxillary anchorage.
1. Intramaxillary anchorage is the anchorage is
which the resistance units are all situated with in the
same jaw. If appliances are placed only in maxillary
or mandibular arch they are considered, intra maxillary
resistance units.

2. Intermaxillary anchorage is anchorage in which
the units situated in one jaw are used to effect tooth
movement in the other jaw. Also called BAKER’S
anchorage.

SELECTION OF ANCHORAGE:
Since anchorage must be selected to make
proper use of the space created by extraction, a
more rational approach of classifying anchorage
would be the one which guides the operator to
make use of the available space.
Accordingly anchorage in mandibular arch
can be put into three classes:
DEPENDING ON ANCHOR LOSS EXPECTED:
•minimum,
•moderate and
•maximum anchorage.

Minimum anchorage mechanics involved
reciprocal forces between posterior teeth and anterior
teeth with no effort to maintain a moment on the
anchor area.
Minimum anchorage mechanics are selected
when the mandibular posterior teeth may be permitted
to migrate mesially into half or more of the extraction
site.


Moderate anchorage mechanics involve placing
an active root thrust or movement on the anchor teeth,
causing bodily resistance in this area.
Moderate anchorage mechanics are selected
to move forward into one fourth to one half of the
extraction site.


Maximum anchorage mechanics involve
reinforcing the anchor teeth with all means available
and reducing the workload required of the anchor area
by developing forces outside the mandibular arch for
as much of the desired tooth movement possible.
Maxillary anchorage mechanics are selected
to move forward into no more than one fourth of the
extraction site.


We have a wide array of appliances
available to gain and preserve anchorage in all
the three dimensions of space. These
adjuncts available are broadly classified into:
• extraoral and
• intra-oral appliances


•The extra oral appliances: Various Headgear
assemblies,or retractors as some author prefers to call
them, essentially constitute this group. Moyers adds
the face mask to this group.

•The intra oral adjuncts can be grouped according to
the plane of space in which they act. The transpalatal
arch acts in all the three dimensions. Whereas lace
backs, Nance/lingual holding arches, lip bumper act in
anteroposterior direction.

•Head gear and face mask give adequate control in
vertical plane. Where as T.P.A. and quad helix help to
preserve the expansion in transverse plane.

HEAD – GEAR
Head gears are classified according to the point of origin of force:
•Cervical – Anchorage obtained from nape of the neck
•Occipital / Straight pull – anchorage obtained from back of
the head. The line of traction is parallel to occlusal plane.
•Parietal / High pull – Anchorage obtained from upper part of
the head and always above the center of resistance of tooth.
•Combi pull – The line of traction is between high pull and
straight pull.
Another variable in the headgear is the outer bow
of the facebow:

The outer bow can be
long, medium or short.


FORCE AND DURATION OF WEAR :
•Most of the authors agree that the amount of force
applied to maxilla by the headgear should be between
400 – 800 gm (Graber, King, Blucher, Moore, Rickets,
Wieslander, Sodensky, Ringberg, Borton, Pfieffer and
Groberty ).
•Light continuous forces seem to produce more dental
changes than skeletal . Whereas heavy force and
intermittent wear is found to produce more skeletal
change.
•According to Marcotte force values of 200 gms per side
in mixed dentition and 500 gms per side in permanent
dentition for 18-20 hrs / day suggested.
•Graber advocates force application of more than 400
gms for 10-12 hrs / day.

FACE MASK:
• It is an extra oral
anchorage source.
• It derives anchorage from
facial bones.
• Sites of anchorage:
1. From skull
2. From chin
3. From skull & chin

• Force applied: approx. 1
pound (450 gms) per side.

TRANSPALATAL ARCH
•Transpalatal arch is a secondary
method of anchorage support in
upper posterior segment.
It is made by 0.045” or 0.051” stainless steel round wire
when it is soldered to the molar bands with loop placed
in the middle of palate so that wire is placed 2 mm from
the roof of palate.
•If the TPA is placed 6-8 mm down from palate it can
induce molar intrusion due to tongue pressure. It can be
used to expand maxillary molar width as well as stabilize
against occipital pull head gear. After cross bite
correction, it will maintain molar position against
undesirable sidewww.indiandentalacademy.com used in the
effects of utility arches
maxillary arch.

NANCE AND LINGUAL HOLDING ARCHES
•The Nance holding arch extends from maxillary molars
to anterior portions of the palatal vault. It is a fixed
appliance. An acrylic button, but half inch or less in
diameter, is attached to the palate. This button must
create light seal with the palate to prevent the creation of
food trap.

•It is important to position the acrylic button against the
vertical component of the palatal vault.
•The stabilizing lingual arch for the lower lie behind and
below the lower incisors, so that it doesn't interfere with
their retraction. The lower lingual arch is conveniently
inserted from distal than from the mesial of molar tube.

LIP BUMPER
•Lip bumper has been used for molar
anchorage, prevention of poor lip habits
and creation of increased space for
mandibular arch.The appliance has
stainless steel wire of 0.045” that spans
the facial surface of mandibular arch
without contacting teeth and is inserted
into tubes attached to the mandibular
molars. Anteriorly the wire is covered
with plastic tubing or a shield made of
acrylic that holds the lower lip away from
the mandibular incisors. Forces from
mentalis muscle are transmitted to
mandibular molars, enabling them to
move to an upright and distal position.

BAKER’S ANCHORAGE:
•It is a type of intermaxillary anchorage.
•Class II traction applied between the lower
molars and upper anteriors as well as Class III
traction applied between upper molars and lower
anteriors are referred to as BAKER’S
ANCHORAGE.


ANCHORAGE PLANNING:
• It is of utmost importance in the success of
orthodontic treatment. Therefore it is very much
essential to carefully assess the anchorage
demands of the individual case and select the most
appropriate treatment plan.
It depends on the following factors:
1. NUMBER OF TEETH TO BE MOVED:
2. TYPE OF TEETH BEING MOVED
3. TYPE OF TOOTH MOVEMENT
4. DURATION OF THE TREATMENT

CONCLUSION
As orthodontic treatment continues to change and
improve, innovative techniques may find acceptance in
certain types of cases. Magnetic forces or electric
stimulation may possibly show the path to an improved
mechanotherapy. But by and large, the basic concept of
arch wires placed in brackets to move teeth will remain
the most efficient method.
Fundamental principles of anchorage laid down by
Tweed have remained unchanged and will continue to
remain so. The list of adjuncts available may increase.
The objective in selection of treatment mechanics is to
have a bag a tricks’ that is large enough to treat most of
the conditions, but not so large as to be unmanageable
to incorporate into one’s practice routine.

Anchorage in orthodontics /certified fixed orthodontic courses by Indian dental academy

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