ANCHORAGE. DEFINITION Resistance to Displacement It obeys Newton's Third Law of Motion “To every...
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Transcript of ANCHORAGE. DEFINITION Resistance to Displacement It obeys Newton's Third Law of Motion “To every...
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