Anchorage1 (2)/certified fixed orthodontic courses by Indian dental academy /certified fixed orthodontic courses by Indian dental academy

ANCHORAGE
www.indiandentalacademy.com
INDIAN DENTAL ACADEMY
Leader in continuing dental education

DEFINITION
• Site of delivery from which an orthodontic
force is exerted.
• Nature and degree of resistance to displacement
offered by an anatomic unit when used for the
purpose of effecting tooth movement.
• Newton’s third law of motion
Action Reaction
• Anchorage is resistance to unwanted displacement
of teeth to the reaction force.

ANATOMICAL UNITS USED FOR
ANCHORAGE
• Teeth
• Alveolar bone
• Palate
• Lips
• Implants
• Head
• Neck
• Forehead
• Chin

Types of Anchorage
1. Simple anchorage
2. Stationery anchorage
3. Reciprocal anchorage
4. Intraoral anchorage
a) Intra maxillary anchorage
b) Inter maxillary anchorage
5. Extraoral anchorage
a) Occipital
b) Cervical
c) Parietal
d) Frontal
e) Genial www.indiandentalacademy.com

6. Reinforced/ Augmented / Multiple
anchorage
a) Intra oral
b) Extraoral
c) Intermaxillary
d) Muscle anchorage
e) Cortical anchorage
f) Absolute anchorage (Implants)

Factors affecting anchorage
1. Teeth – Embeded in alveolar bone.
Anchorage value depends upon-
A) Form of roots
a) Round roots – 50% PDL fibres resist force/
displacement in any direction.
b) Flat roots – 50% PDL fibres resist force in
M-D direction. e.g. mandibular incisors, buccal
roots of maxillary molars.
c) Triangular roots – 2/3rd
of fibres resist force/
displacement e.g. maxillary canines and central
incisors.

• Maxillary molars have tripod arrangement of
roots.
Palatal root – Large round. Resists extrusion.
Buccal roots – Small. Resist intrusion.
B) Size and number of roots.
( root surface area)
Multirooted tooth is more resistant to displacement
than a single rooted tooth.
Anchorage value of any tooth is proportional to it’s
root surface area.

C) Root length -
Longer the root, greater is it’s resistance
to movement. e.g. canines.
D) Inclination of roots –
Distal inclination of roots resists distal
movement.
E) Position of tooth in the dental arch –
Mandibular second molar offers
maximum resistance to mesial movement
as it is located between the mylohyoid
ridge and
external oblique ridge.

F) Shape and size of crown of tooth -
Tooth with carious or fractured crown is
poor abutment tooth.
2) Direction of force relative to direction of
growth -
General direction of growth is forward,
outward and occlusally.
Force in opposite direction encounters
maximum resistance.

3) Direction of force relative to the axis of
tooth -
Tooth resists intrusive movement the
most.
4) Type of force - Bodily movement encounters
more resistance than tipping.
5) Amount of force –
Capillary blood pressure is 20-26 gms./cms.
High force – Compression of PDL.
Undermining resorption.
Delayed tooth movement.
Light force – Frontal resorption.
Rapid movement.
Less strain on anchor teeth.

Optimum force -
1 mm. Per month tooth movement.
Lightest force which produces
maximum response.
No discomfort to the patient.
Located at the beginning of the plateau
of the force-movement graph.

6) Good intercuspation
Good cuspal occlusion gives better
anchorage value.
7) Proximal contiguity –
Contiguous teeth are better ancors than single,
isolated teeth.
8) Associated muscle function –
Alfred Rogers harnessed muscle force to
effect tooth movement and to conserve
the anchorage.

9) Age of patient – Anchorage value of
toothdiminishes with age.
10) Individual tissue response –
This varies with patients.
11) Friction at wire bracket interface –
NiTi wires have rough surface.
Surface elevations (asperities) increase
friction. Stick-slip phenomenon occurs.
Titanium cold welds with S.S.
Highr coefficient of friction.
NiTi has 50% and Beta Ti has 80% Titanium.
Friction of wires is reduced by surface
implantation with N2,C ions.www.indiandentalacademy.com

Asperities

Effects of Friction
Increased force requirements

Force – Anchorage relation

Simple Anchorage
• In this type of anchorage the anchor teeth are
subjected to tipping force.
• Greater number of teeth are used to move less
number of teeth within the same dental arch.
• Hnce it is Intraoral and Intramaxillary type of
anchorage.
• Examples :-
(a) Removable aplliances using active components
like Labial bow, Finger spring, Z spring,
Expansion screw etc.
• Simple anchorage has lesser anchorage value than
stationery anchorage as tooth can be easily tipped
but bodily movement requires complex mechanics.www.indiandentalacademy.com

Finger spring

Z spring

Canine retractors

Expansion screw

Stationery anchorage
• Anchor teeth are subjected to reaction force which
will move them bodily.
• Anchor teeth are not permitted to tip.
• Anchor tooth must move bodily.
Other teeth tip.
• Tooth offers greater resistance to bodily movement
than tipping as force is distributed throught the
length of clinical root.

Examples of stationery anchorage
1) Fitted labial bow. Splinting effect.
2) Incisor capping of acrylic in
Activator, Swed plate. Splinting effect.
3) Anchor bend mesial to molar tube
of Begg Technique.
4) Breaking arch of Begg Technique using
(a) Uprighting springs on canines.
(b) Torquing auxiliary on incisors.

Fitted Labial Bow
Splinting effect

Incisor capping of acrylic
Activator Swed Plate
Splinting effectwww.indiandentalacademy.com

Begg’s Anchor bends

Breaking arch
Uprighting spring

Intra-oral Anchorage
• The anchorage sources are situated within
the oral cavity.
• It can be simple, stationery, reciprocal or
reinforced.
• It can be of two types –
(I) Intra maxillary anchorage.
(II) Intermaxillary anchorage.

Intra maxillary anchorage
• Anchorage source is within the same jaw.
• Sites in other jaw, or extraoral sites not utilized.
Examples -
(i) Removable appliances like Z spring, Finger
spring, Expansion plates.
(ii) Retraction of anterior teeth with horizontal
(Cl-I) elastics, closing loop arch wires.
(iii) Nance button - Nance holding arch, Hilger’s
Pendulum appliance.
(iv) Lip bumper.
(v) Trans palatal arch (TPA).
(vii) Micro implants. (MIA or Absolute anchorage)

Closing loops
Retraction
Horizontal elastics

Trans Palatal Arch

Nance Appliance

Hilger’s Pendulum Appliance

Microimplants

Intermaxillary Anchorage
• Anchor units in one jaw are used to effect
tooth movement in the other jaw.
• Tooth movement in the two arches may not
be equal.
• Hence it is not truly reciprocal.
• It is Intraoral and Reinforced.

Examples
(i) Functional Appliances.
e.g. Activator, Bionator, Twin block etc.
By harnessing muscle force -
• Upper dental arch is distalized.
• Lower dental arch is mesialized.
• This helps to correct Cl-II, Cl-III
malocclusion.

Activator

Intermaxillary Elastics
• Cl-II, Cl-III elastics.
This is called as Baker’s Anchorage.
• Cross Bite elastics (Criss-cross elastics).
• Diagonal elastics.

Cross Elastics
Cl-II Elastics

Reciprocal Anchorage
• Two teeth or two groups of teeth move to
an equal amount and in opposite direction.
• Both these groups should have same resistance
value. If not the movement will not be equal.
Examples -
(i) Correction of midline diastema
(ii) Bilateral symmetrical expansion.
(iii) Correction of posterior cross bite.

Midline diastema
closure
Expansion
Cross elasticswww.indiandentalacademy.com

EXTRA ORAL ANCHORAGE
• Anchorage is derived from sites outside the
mouth.
e.g. Head,neck forehead,chin.
(i) Occipital anchorage – High pull H.G.
(ii) Cervical anchorage – Low pull H.G.
(iii) Cranial/ Parietal anchorage – Vertical pull H.G.
(iv) Forehead/Frontal anchorage – Reverse pull H.G.
(v) Chin – Reverse pull H.G.

Indications
• Extraoral anchorage is usually employed
for -
(i) Correction of basal maxillomandibular
jaw relationship i.e.Growth modification
in skeletal Cl-II, Cl-III cases.
(ii) To prevent mesial movement of posterior
teeth to preserve anchorage during
retraction of anterior teeth.

Head gear force
• The force is delivered through a face bow
or J hook which is attached to headcap or
neckstrap or hook on the bar of RPHG.
• Face bow consists of outer bow and inner
bow joined in center.
• Inner bow is inserted in the H.G. tube attached to
the SS band on 6/6 or in arch wire hook or in the
removable appliance.
• Outer bow is connected to headcap or neckstrap.
• Extra oral elastics deliver the force.

Outer bow
Inner bow
F
Face bow
High Pull H.G.
Cervical Pull H.G. Combination Pull H.G. Reverse Pull H.G.

High Pull Head Gear
• Restricts anterior growth of maxilla.
• Restricts vertical growth of maxilla.
• Restricts eruption of maxillary molars.
• Causes distal movement of maxillary
molars.
• Prevents mesial movement of maxillary
molars (reinforces anchorage).

Cervical Pull Head Gear
• Restricts anterior growth of maxilla.
• Causes distal tipping of maxillary molars.
• Causes extrusion of maxillary molars.
• Prevents mesial movement of maxillary
molars( reinforses anchorage).

Combination Pull H.G.
• Causes distal bodily movement of maxillary
molars.
• No rotation of maxilla/ palatal plane.
• No rotation of occlusal plane.
Vertical Pull H.G.
• Exerts vertical pull.
• Used for true intrusion of maxillary incisors.
• Chin cup treatment with vertical treatment.

Face mask/Reverse pull H.G.
• Indicated in skeletal class III cases with
deficient maxilla.
• Takes support from forehead pad and
chin cup.
• Protraction force to maxilla through the
extra oral elastics.
• Direction of force -
Forward, downward, inward.
• Amount of force – 12 Ounce per side.
1 Ounce = 28.33 grams.
• Examples – Delaire, Petit, Hickham face masks.

Position/ Length of outer bow
Vertical position of outer bow –
High, straight, low.
Length of outer bow –
Short, medium, long.

Reinforced/Augmented/Multiple
Anchorage
• When simple anchorage is insufficient to
withstand reaction force, the anchorage
is reinforced/augmented by various
methods.
• Particularly in maximum/critical anchorage
cases

Types of reinforced anchorage
(1) Tooth and Tissue borne anchorage –
Palatal or lingual removable appliances.
(2) Intra arch(intra maxillary) anchorage –
(i) Nance holding arch.
(ii) Anterior inclined plane.
(iii) Trans palatal arch(TPA).
(iv) Implants.
Titanium screws -
9,10.12 mm length. 1-1.2 mm width.
Non osseointegrated.

(3) Inter maxillary anchorage –
Cl-II, Cl-III elastics (Baker’s anchorage).
Diagonal, cross bite elastics.
Functional appliances.
Inclined plane.
(4) Muscle anchorage –
Lip bumper.
Mayne appliance.
Denholtz muscle anchorage appliance.
Oral screens.
Frankel’s appliance.

Inclined plane
60 degree to occlusal plane.
Guides lower jaw forward.
Exerts backward force on the
maxillary appliance.

Lip bumper Denholtz appliance
Frankel Appliance Screening effectwww.indiandentalacademy.com

(4) Cortical anchorage -
Roots placed against cortical bone.
Cortical bone is compact, resistant to
resorption.
e.g. Rickett’s Bioprogressive appliance.
Disadvantages – Root resorption.

Gradation of anchorage
(1) Maximum anchorage (critical) –
Anchor teeth should not move.
Anchorage is reinforced.
Frictionless mechanics is prefered for
space closure.
(2) Minimum anchorage –
Some movement of anchor teeth is
permitted.
(3) Moderate anchorage –
Intermediate.www.indiandentalacademy.com

60 : 40 space closure
60 % retraction of anterior teeth.
40 % forward movement of posterior teeth.
(1) One step space closure with a frictionless
mechanics.
(2) Two step space closure with sliding mechanics.
Retraction of canines first followed by
retraction of incisors.
(3) Distal tipping followed by uprighting of the
anterior teeth.

Signs of anchor loss
(1) Mesial movement or lingual rolling
of molars.
(2) Space closure without sufficient
retraction of anterior teeth.
(3) Proclination of anterior teeth.
(4) Increase in overjet.
(5) Spacing of teeth.
(6) Extrusion/ distal tipping of molars.
(7) Unwanted change in molar relationship.
(8) Appearance of cross bite.

Methods/Strategies to control anchorage
(1) Include as many teeth as possible in the
anchorage unit. Ratio of PDL area –
2:1 without friction
4:1 when there is friction.
(2) Move minimum teeth at a time.
(3) Use light forces.
(4) Use differential forces(Begg technique).
(5) Frictionless mechanics for space closure.
(6) Subdivision of desired forces –
Use of sectional arches for intrusion,retraction.www.indiandentalacademy.com

(7) Movement by tipping followed by
uprighting of teeth.
(8) Two step space closure –
Retraction of canines first followed by
retraction of incisors.
Divide and conquor ( Tweed, Alexander).
(9) Anchorage preparation –
Distal tipping of posterior teeth in Tweed’s
technique.
(10) Reinforcement of anchorage.

Prepared anchorage

60 : 40 space closure Tipping of anterior teeth
against
Bodily movement of posterior
teeth.

Canine retraction
Incisor retraction
Thank you
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Anchorage1 (2)/certified fixed orthodontic courses by Indian dental academy /certified fixed orthodontic courses by Indian dental academy

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Anchorage1 (2)/certified fixed orthodontic courses by Indian dental academy /certified fixed orthodontic courses by Indian dental academy