Sources of Anchorage

ANCHORAGE
Presented by- Samruddhi Bengal
Roll no. -04

-These are anatomical units and/or regions which are
utilized to provide resistance to movement i.e.anchorage..
-It is classified into two sources
1.Intraoral source
2.Extraoral source
|. Intraoral source – It includes the teeth, alveolar bone,
Basal jaw bone, musculature & cortical plate of the
socket

1.THE TEETH
- whenever one set of teeth(anteriors) are moved
orthodontically, the remaining set of teeth (posteriors) of the
oral cavity can act as anchorage or resistance units.
• The anchorage potential of teeth depends on factors such
as:
- Root morphology- number, size, length
- Root surface value or periodontal surface area
- Position and inclination of tooth in the arch
- Interdigitations of the cusp etc.

A- Root surface value- The anchorage value of any tooth
is roughly equivalent to it’s root surface area
- The distribution of fibres on the root surface determines
anchorage.The more the fibres the better the anchorage
potential

B-Root form or root Shape
1.ROUND ROOTS- Resist horizontal forces
e.g.Bicuspids,Palatal root of maxillary molars
2.FLAT ROOTS – Resist mesio-distal movement
e.g.Mand. Incisors and molars, Buccal root of maxillary
molars
3.TRIANGULAR ROOTS- Maximum resistance to
displacement
e.g. Maxillary anteriors

C. Size and number of roots
longer the root, the deeper it is embedded in bone
and the greater is its resistance to displacement as the
periodontal surface area of attachment increases.
The greater the surface area the greater the
periodontal support and hence , greater the anchorage potential
- The anchorage potential of root form is in following order
Large and longer roots > Short and small roots
Multirooted > Single root
Flared multiroots > Fused roots

D.Position and inclination of teeth
-The root surface value of maxillary first molar is greater
than mandibular first molar But the anchorage value of
mandibular 1st molar is greater due to it’s position of roots
in between two cortical plates
-The axial inclination of a tooth dictates the anchorage
value of the tooth

A greater resistance to
displacement is offered
when the tooth is
attempted to be moved
in a direction opposite
to that of axial
inclination

F. Ankylosed teeth – Ankylosed teeth are directly fused to the
alveolar bone devoid of periodontal ligament. Orthodontic treatment is
not possible and they can therefore serve an excellent anchor
whenever possible
G. Intercuspation – Good intercuspation lead to greater anchorage
potential.Interlocking of the cusps prevents the mesial drift of the teeth
H.Contact point – Teeth with tight and broad contact provide greater
anchorage
I.Mesial drift – Resistance value is least in downward and forward
direction.Maxillary posterior teeth drift more readily by mesial
migration.

2) Alveolar bone
- The alveolar bone that surrounds a tooth offers more resistance to
tooth movement upto a certain limit.
- Less dense alveolar bone offers less anchorage
- More mature bone increases anchorage
3) Cortical bone
- The cortical bone is more resistant to resorption than medullary bone
• E.g. Rickett’s Bioprogressive appliance
4)Basal bone
-certain areas act as resistance areas and provides good anchorage
like Hard palate and lingual surface of mandible
e.g. – Nancy palatal button

||. EXTRAORAL SOURCES OF ANCHORAGE
Anchorage in which resistance units are situated outside the oral cavity
sources are-
1. Cranium
2. Facial bones
3. Back of the neck

– Headgears derive anchorage from occipital
and parietal regions of the cranium.These are used along
with a facebow to resist growth of maxilla or to move
maxillary teeth distally
- The frontal bone(forhead region)
and mandibular symphysis(chin area) are used as a
resistance units during face mask therapy.
headgear that make use of anchorage from the forehead
and the chin to move maxillary bone or dentition in mesial
direction are called reverse pull headgear

– The cervical headgears anchorage are
from back of the neck or cervical region.They are also used to
bring about changes in the maxilla or maxillay
teeth .

|||. Muscular Anchorage
• The normal tonus of the perioral musculature can be utilized as
anchorage powers for effecting the tooth movement.
• Dental anchorage can be increased by making tonicity of labial
musculature.
• Lip bumper is an appliance that makes use tonicity of lower lip
musculature and enhances the anchorage potential of mandibular
molars preventing their mesial movements and if required results
in distalization of molars.
• The same appliance if used in upper arch is called as Danholtz
appliance

These are appliances or methods to reduce the amount of
tooth anchorage necessary to correct malocclusion. In other
words they reduce the burden on anchor tooth.
- Forces are generated from
Extraoral appliances such as headgears and chin by
utilizing Extraoral sites such as cranium,back of the neck
and face bones Can be used in anchorage
- A removable appliance in which an
upper anterior inclined plane is incorporated.It results in
forward gliding of the mandible during closure of the jaw.

–
-This is a wire that spans the palate in a transverse direction connecting first
Permanent molars of either side.They are used in fixed mechanotherapy to
augment.It provides anchorage in Sagittal, transverse and vertical plane

–
- It’s function is similar to
TPA and is used in Lower
arch
- It acts as an anchorage
device
- It is also used for
distalisation of molars and
also can be used as a space
maintainer

-It utilizes palatal area as
source of anchorage
- It is similar to Nancy palatal
arch
but is limited to lower arch

•It is very essential for success of orthodontic treatment
• The anchorage requirement depends on no. of factors
1.Number of teeth being moved- The greater the no. of teeth being moved,
greater is the anchorage
2.Type of teeeth being moved- The movement of a single rooted anterior teeth
offers lesser strain on anchorage than the Multirooted posterior teeth
3.Type of tooth movement-Bodily tooth movement taxes more anchorage as
compared to the tipping movement which offers realtively a lesser strain on the
anchorage unit
4.Duration of tooth movement- Treatment of a prolonged duration places an
undue strain on anchorage.Shorter the duration, lesser on the burden on
anchor tooth

•It is the movement of the reaction unit or the anchor unit
instead of the teeth to be moved
•Gianelly and Goldman suggests the term maximum,
moderate and minimum to indicate the extent to which the
active and reactive units should move when force is applied
•In spite of the precaution taken in planning and
anchorage,a certain amount of unwanted movement of the
teeth invariably occurs during orthodontic treatment.Such
unwanted movement of anchor teeth is called 'anchorage
loss’.
• This is particularly seen in treatment of class II division 1

•Mesial movement of molars
•Closure of extraction Space by movement of posterior
teeth
•Proclination of anterior teeth
•Spacing of anterior teeth
•Change in molar relations
•Buccal crossbite of upper posteriors

• To concentrate the force needed to produce tooth
movement where it is desired
• To dissipate reaction force over as many other teeth as
possible, keeping the pressure in PDL of anchor teeth as
low as possible
• Few teeth are moved at a time
• As many teeth are included in anchorage unit
• Appliance produce light forces
• Removal of etiological agents such as abnormal oral
habits

Sources of Anchorage

More Related Content

What's hot

Similar to Sources of Anchorage

Recently uploaded

Sources of Anchorage