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 Unit 2)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 Anchorage Resistance to tipping  Stationary Anchorage Resistance to bodily movement  Reciprocal Anchorage Two 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) CervicalLow pull Head gear Occipital Medial pull Head gear CranialHigh pull Head gear FacialChin cup, Face mask Muscular Vestibular Shields

Transpalatal Arch

Lingual Arch

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 (2/3 rd 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 (1/3 rd space utilized by the movement of anchor unit) Absolute Anchorage (Absolutely no movement of anchor unit e.g. Implants)

 Anchorage Loss Unintentional movement of anchor unit  Anchorage Burn Intentional movement of anchor unit

Principals of Anchorage 1 st Principal of Orthodontic Anchorage A tooth with a large root surface area has a greater anchorage value than with a small root surface area 2 nd 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