Tooth Movement

Question 1

Tooth movement define ?

Answer 1

Occurs as consequence the bone has to remodel as specified coupled sequences of resorption and formation events to replace existing bone.

Or

Physiological I.e. in response to muscular or orthodontic forces leads to bone being laid down in tension sites and bone being resorbed at pressure sites.

Question 2

Optimal forces for tooth movement

Answer 2

• Ideal forces in orthodontic tooth movement are those which over come capillary blood pressure.

Question 3

What happens if excessive pressure?

Answer 3

Excessive pressure result in Hyalinisation where cellular component of periodontal ligament disappears

Question 4

Ground glass appearance define ?

Answer 4

-Hyalinised zone assume “ground glass “ appearance but returns to normal once pressure is reduced and periodontal ligament repopulated with normal cells.

-in this case osteoclast appear to “undermine” bone rather than resorbing at frontal edge.

Question 5

Tendency of forces should be use ?

Answer 5

• low constant force
  light and low levels of forces That are capable of moving teeth.

-intermittent forces generate more bone turnover than continuous forces

Question 6

Pressure side - ideal tooth movement

Answer 6

• Pressure side of tooth being moved in the direction
• Osteclasts all lined up resorbing bone known as Frontal resorption
• Osteoclast comes from monocytes in the blood.

Question 7

Tension side - ideal tooth movement

Answer 7

• No osteoclast, Pale pink new bone has been laid down by Osteoblast

Question 8

Hyalinisation ( Sterile Necrosis)

Answer 8

• Excessive pressure cause “ ground glass appearance “ of cells called hyalinisation

Question 9

Tooth movement - Optmimum Force

Answer 9

Pressure side
- Cell proliferation occurs within the periodontal ligament in area of compression and osteoclasts in from surrounding blood vessels

• Resorption occurs adjacent to the area of pressure within days

Tension side

• On tension side periodontal fibres are stretched and there is proliferation of fibroblasts and osteoblast. Osteoid is deposited on socket wall and remodelled into mature bone.

Question 10

Tooth movement Excessive Force

Answer 10

• If excessive force is applied direct resorption of the bone doesn’t occur due to compression of blood vessels
• Sterile necrosis ( Hyalinisation ) structure less microscopic appearance
• After few days indirect resorption occurs then tooth moves (undermining resorption)

Question 11

Tooth movement how much optimal Force?

Answer 11

• Below capillary pressure (20 -25 g/cm2)
• Depends on Root surface area
• Type of tooth movement (tipping or bodily movement)

Question 12

What are consequences of excessive force?

Answer 12

• Delay in tooth movement
• Increased risk of Anchorage loss
• greater discomfort of tooth being moved
• Increased tooth mobility
• Greater risk of root resorption

Question 13

Duration of force

Answer 13

• Clinical tooth movement : 6 hours per day
• Optimal tooth movement - continuous 24 hours per day
  -Due to irregularity of tooth socket walls forces are not even and there may be pockets of excessive force

Question 14

Root resorption

Answer 14

• Minimal 1mm usually-
• ## varies from tooth to tooth U2s’ lose 2.5mm Molars 1mm

Question 15

Factors increase Risk of root resorption? Tooth movement

Answer 15

• Moving teeth against buccal and lingual bone
• Torqueing teeth (3rd order movement)
• maxillary and mandibular surgery for jaw correction
• Treament with Xtns are part of plan

Question 16

Four Theories of Tooth movement ?

Answer 16

1- The biomechanical / cellular response theory
2- The Piezoelectric theory
3- The pressure tension hypothesis
4- The hydrodyanamic theory

Question 17

Types of tooth movement

Answer 17

1- Tipping 35-60 g
2- Bodily movement 70-120g
3- Intrusion 10-20 g
4- Extrusion 35-60 g
5- Rotation 35- 60g
6- Torque 50-100 g

Question 18

Tipping movement

Answer 18

• 35 - 60g
• Mesio distal movement
• e.g URA , fixed with round wires

Question 19

Bodily movement

Answer 19

70- 120 g
- root stays same

Question 20

Three orders of movements?

Answer 20

-First order bends - Rotational movement, bucco lingual / labio lingual.

• Second order bends - Tipping ( Mesio distal movement)

-Third order bends - Torque

Question 21

How much Force in tooth to move?

Answer 21

-100 - 200g . Otherwise it will take time to move