ANCHORAGE

DEFINITION

Resistance to Displacement

It obeys Newton's Third Law of Motion

“To every action there is an equal & opposite reaction”

Each orthodontic appliance consists of two elements

1) Anchor Unit2) Moving Unit

Intra-oral {Extra-oral {

Intra-maxillary

Inter-maxillary

[Simple Anchorage

Stationary Anchorage

Reciprocal Anchorage

{Single

Compound

Reinforced

Cervical

Occipital

Cranial

Facial

Types of Anchorage

Space Availability {Minimum Anchorage

Moderate Anchorage

Maximum Anchorage

Absolute Anchorage

Classification of Anchorage

Manner of Force Application

Simple AnchorageResistance to tipping

Stationary Anchorage Resistance to bodily movement

Reciprocal AnchorageTwo or more teeth moving in opposite

direction (Resistance to each other is equal and opposite)

According to Jaw Involved

Intra-maxillary (Anchorage established in same jaw e.g. Intra-maxillary elastics, TPA)

Inter-maxillary (Anchorage distributed to both jaws e.g. Inter-maxillary elastics)

According to Site Involved

Intra-oral (Anchorage established within mouth e.g. TPA)

Extra-oral (anchorage obtained from outside mouth) Cervical Low pull Head gear

Occipital Medial pull Head gearCranial High pull Head gearFacial Chin cup, Face mask

Muscular Vestibular Shields

Transpalatal Arch

Lingual Arch

Lip Bumper

Lip Bumper

High Pull Headgear

Straight Pull Headgear

Cervical headgear

Face Mask

Intermaxillary elastics

Implants

According to Number of Units

Single or Primary Anchorage (Anchorage involving one teeth)

Compound Anchorage(Anchorage involving two or more

teeth)

Reinforced Anchorage(Addition of non-dental anchorage)

According to Space Available

Minimum Anchorage (2/3rd space utilized by the movement of anchor unit)

Moderate Anchorage(1/2 space utilized by the movement of anchor unit & remaining 1/2 by the movement of moving unit)

Maximum Anchorage(1/3rd space utilized by the movement of anchor unit)

Absolute Anchorage(Absolutely no movement of anchor unit e.g.

Implants)

Anchorage LossUnintentional movement of anchor unit

Anchorage BurnIntentional movement of anchor unit

Principals of Anchorage

1st Principal of Orthodontic Anchorage

A tooth with a large root surface area has a greater anchorage value than with a small root surface area

2nd Principal of Orthodontic Anchorage

Tooth which is free to tip has less anchorage value than a tooth which is restricted in tipping by the application of a force couple

Anchorage Value

Basics Determinants of Anchorage Value

Force Magnitude

Pressure Distribution in PDL

Root Morphology

Space Available

Neighbouring Structures

Anchorage value can be improved

1) Incorporate as many teeth as possible in anchorage unit

2) Reduce number of teeth in moving unit

3) Use of anchorage bends

4) Reduce the force applied to the optimal for producing the required tooth movement

5) Reinforce intra-oral anchorage with extra-oral anchorage

6) Use of palatal or lingual arch

7) Use of intra/inter maxillary elastics

8) Use of lip bumper------anchorage from musculature

9) Cortical anchorage

Anchorage to be Considered

In Antero-posterior plane (Anchorage loss appears in the form of movement of

anchor unit in antero-posterior plane e.g. bodily mov. or tipping)

In Vertical plane(Anchorage loss appears in the form of extrusion of molars or Tip back of molars so care must be taken when planning to treat High angle cases)

In transverse plane

(anchorage loss in the form of buccal flaring)

Conclusion

Anchorage Management

Anchorage Planning