ANCHORAGE IN
ORTHODONTICS
Maryam ArbabHouse OfficerDepartment Of OrthodonticsSBDC
DEFINITION
Anchorage in orthodontics is defined as the resistance to displacement offered by an anatomic unit for the purpose of tooth
movement
CLASSIFICATIONAccording to force application
simple stationary reciprocal
The manner & application of force is such that it tends to change the axial inclination of teeth that forms the anchorage unit
The manner & application of
force tends to displace the
anchorage unit bodily in the
plane of space in which the force is
being applied
The resistance offered by two malposed units
when the dissipation of
equal &opposite force move each unit towards a
normal occlusion
Simple anchorage : Removable appliance incorporating a screw for buccal movement of a platally placed premolar
Stationary anchorage
1.Correction of midline diastema using elastics.Reciprocal
anchorage: Midline diastema closure
3. Finger Springs used to close amidline diastema.
2. Arch expansion using a removable appliance incorporating a coffin spring.
According to Jaws Involved :1. Intra-maxillary
The anchor units and teeth to be moved are situated in same arch.
2. Inter-maxillary
The anchor units and teeth to be moved are situated in opposite arches
Example
CLASS II ELASTICS CLASS III ELASTICS
According to number
Single or Primary Compound Reinforced
or Multiple
Resistance provided by single tooth OR a single tooth with more alveolar support is used to move one with lesser alveolar support.
More than one tooth in anchorage unit OR anchorage provided by more than one tooth with more support to move a tooth with less support.
More than one type of resistance unit is utilized. E.g: To augment the intra-oral anchorage, extraoral anchorage, TPA,& lingual arch is used
single compound
reinforced
Lingual ArchTranspalatal Arch
Extra-Oral Anchorages
According to Site :
Intra - oral Extra oral Muscular
The intraoral sources of anchorage include the:Soft tissuesTeethBone (palatal vault)Basal jaw bone
The extraoral sources of anchorage include the:Occipital boneBack of the neckcranium & face
Perioral musculature
intraoralExtra oral : Occipital headgear
Musculature ( lip bumper)
PRINCIPLES OF ANCHORAGE When one teeth moves, other serves as an
anchor units depending upon : - root size - number of root - root inclination
Increase anchorage value by restricting anchored teeth to bodily movement
Do not use heavy force which leads to hyalinization
ANCHORAGE PLANNING Anchorage requirements depends on a
number of factors, listed as :
Number of teeth being moved : Greater number of teeth being moved ,
greater is the demand of anchorage
Type of teeth being moved : Movement of anterior teeth provides lesser
strain , compared to multirooted tooth
Type Of Tooth Movement : Bodily movement applies greater strain
on anchorage compared to controlled tipping tooth movements
Duration of Treatment : Prolonged duration of treatment places
undue strain on the anchorage
Occlusal Interlock : A good buccal occlusion may act to resist
tooth movement
ANCHORAGE DEMAND Anchorage demand can be of three types :-
Maximum anchorage
Moderate anchorage
Minimum anchorage
Not more than 1/4th of the extraction space should be lost by forward movement of anchor teeth
Anchor teeth can be permitted to move forward into 1/4th to ½ of extraction space
More than half extraction space can be lost by anchor teeth moving mesially
ANCHORAGE LOSS Certain amount of unwanted movement of the anchor teeth
invariably occuring during orthodontic treatment .
Anchorage loss can occur in all three planes:
Sagittal plane : - mesial movement of molars - proclination of anterior teeth
Vertical plane : - extrusion of molars - bite deepening due to anterior extrusion
Transverse plane : - buccal flaring due to over expanded arch
form - lingual dumping of molars
METHODS TO CONTROL ANCHORAGE
1. Reinforcement :- Addition of teeth to anchorage unit Reinforcement may also include forces
derived from structures outside the mouth
2. Subdivision of desired movement :- Pit the resistance of a group of teeth
against the movement of a single tooth
3. Tipping / Uprighting :- Tip the teeth and then upright them rather than
moving them bodily
4. Friction & Anchorage control strategies :- one step space closure with frictionless
appliance
Two step space closure sliding the canine along the arch wire , then retracting the incisors
Two step space closure , tipping the ant. segment with some friction and then uprighting the tipped teeth
5. Skeletal Anchorage :- Temporary skeletal anchorage is derived
from: implants miniplates
Temporary Anchorage Devices (TADs)
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