Anchorage

Question 1

Define Anchorage?

Answer 1

• Resistance to unwanted tooth movement
• Resistance of forces generated in reaction to the active component of appliance
• Newton’s Third law of motion - Every action there is an equal and opposites

Question 2

Principle of Anchorage

Answer 2

1-Differential force theory - Rate of tooth movement is related to force per unit root surface area.

2-Increased roots of tooth increased resistance to tooth movements increased Anchorage value.

3- no relation to surface of tooth.

4- Not linear relationship b/w surface area and tooth movement therefore factor involved - PDL.

5- Large individual variation in rate of tooth movement for particular force applied.

6- Optimal level exists after which if you increase the force there is no increase tooth movement only increase strain on anchor units.

7- Increase number of tooth in anchor unit to increase surface area.

8- Increased anchorage value by restricting anchor teeth to bodily movement.

9- Can view anchorage in terms of space management- Maximise wanted tooth movement and minimise unwanted tooth movement.

10- always consider 3 dimension: AP , lateral , vertical

Question 3

Loss of Anchorage

Answer 3

• Unwanted tooth movement and space loss.

E.g . Mesial movement of Upper first Permanent molar during premolar extraction space closure

Question 4

Anchorage loss and Anchorage Burn

Answer 4

• Anchorage loss - Unintentional movement of anchor unit
• Anchorage burn - intentional movement of anchor unit

Question 5

Space management.

Answer 5

• Maximise wanted tooth movement
• minimise unwanted tooth movement

Question 6

Types of Anchorage

Intra oral

Answer 6

• Simple Anchorage
• Compound Anchorage
• Stationary anchorage
• Reciprocal anchorage

Question 7

Simple Anchorage

Answer 7

• 1 tooth against another 1-1

Question 8

Compound anchorage

Answer 8

• More than 1 tooth in anchor unit

1- Intra maxillary - same arch.-bonding 7s’
2- Inter maxillary- Opposite arches ( class 2-3 elastics traction )

Question 9

Reciprocal anchorage

Answer 9

• Equal tooth movement towards each other.
• e.g powerchain to close midline diastema

Question 10

Stationary Anchorage

Answer 10

• Resistance to bodily movement
• force tends to displace Anchorage unit bodily in the plane of space in which force is being applied

-e.g Tads

Question 11

soft tissue / Bone

Answer 11

• Soft tissue - lip bumper
  -Bone - Nance button , palatal vault in URA.
  -

Question 12

Why mandibular teeth have greater anchorage value than maxillary teeth?

Answer 12

• Cortical plates provide increased resistance of tooth movement than cancellous bone.
• Mandibular teeth have greater anchorage value than maxilla teeth.

Question 13

Extra oral Anchorage

Answer 13

• Anchorage from cranial vault/ basal bones
• Protraction headgear ( reverse headgear)
• Extra oral anchorage

Question 14

How can you increase Anchorage?

Answer 14

• Band all molars

Question 15

Factor affecting anchorage

Answer 15

• Type of tooth movement
• Root surface area
• Sk pattern
• Occlusal interdigitation
• Tendency for tooth movement in the arch.
  Maxillary teeth have greater tendency for mesial drift.

Question 16

Reinforcement of Anchorage?
Mechanism

Answer 16

• Increase the number to teeth in anchor unit
• Making movement of anchor teeth more difficult.
• Intermaxillary traction
• Extractions, Extraction pattern
• Implants.

Question 17

Anchorage reinforcement
Choice of appliances

Answer 17

• Removable appliances- Mucosa and underlying bone , Nance button
• Fixed appliance : Lower friction system

Question 18

Supplement Anchorage?

Answer 18

• Xtn decision
• Bond/ band 2nd molar to increase anchorage unit
• Extra oral anchorage
• Lingual arch
• Tanspalatal arch / nance button
• inter maxillary elastics
• Fixed with less friction.
• Implants - Tads/ mini screw

Question 19

What happen when nance wedge in?

Answer 19

-Loss of Anchorage

Question 20

Why do we use TPA for anchorage

Answer 20

• Use to stop forward movement for 6’s

Question 21

TAD - Temporary anchorage device

Answer 21

• Important factors with implants
• Quick and easy to insert without damage to adjacent teeth
• Convenient for application of orthodontic forces
• Immediate loading
• Easily removed
• No patient discomfort at insertion or removal

Question 22

How can we reduce anchorage strain?

Answer 22

• Tip teeth rather than bodily movement
• light force
• low friction - self ligating bracket
• Seperate retraction of individual tooth
• push rather than pull e.g canine retractions
• correct centrelines one tooth at time

Question 23

Assessment of Anchorage need?

Tooth movement required

Answer 23

• Space required to complete alignment; how much anchor units be allowed to move.
• Bodily or tipping . Increased for bodily movement decreased for tipping movement.
• Angulation of teeth . Increased anchorage required for mseially inclined canine less than upright or distal inclined canine.
• Inclination of teeth - Increased anchorage required for proclined incisors less than Retroclined incisors

Question 24

What are sources of anchorage ?

Answer 24

• teeth
• implant
• bone
• extra oral

Question 25

Source of skeletal anchorage devices?

Answer 25

- orthodontic Implants - palatal implants or onplant - Zygoma ligature - mimi plates - mini screws

Question 26

AP anchorage

Answer 26

- Extraction choice

Question 27

What are indication of sufficient anchorage?

Answer 27

- Do you have enough space to move teeth - normal Overjet - planned Molar relationship

Question 28

Mandible teeth has greater Anchorage value than maxillary teeth? Why?

Answer 28

- Cortical plates (mandible) provide greater resistance to tooth movement than Cancellous bone (maxilla).

Question 29

Anchorage creation

Answer 29

- Distal movement of upper buccal segment with extra oral headgear e.g Nudger appliance - Implants and distalisation. - fixed molar correctors e.g pendulum appliance (tends to Procline upper incisors) - lip bumper to distalise lower molar (tends to Procline LLS). - Xtn pattern / functional appliance - alter anchorage balance

Question 30

How can you tell you have sufficient Anchorage?

Answer 30

- Do you have enough space ? - To move teeth so they are straight. - Have a normal Overjet between 2-4 mm. - Planned molar relationship. Then yes you have sufficient Anchorage