Physiology Of Tooth Movement

Question 1

What types of tooth movement are there?

Answer 1

Tipping

Bodily movement

Intrusion

Extrusion

Rotation

Torque

Question 2

What are the optimum forces for each type of movement?

Answer 2

Tipping, extrusion and rotation = 35-60g

Intrusion = 10-20g

Bodily movement = 150-200g

Torque = 50-100g

Question 3

What is the difference in movement in light and heavy forces?

Answer 3

Light forces exhibit a linear slow movement of teeth

Heavy forces have a rapid movement, followed by periods of stasis, then period of movement.

Question 4

How does duration of force affect tooth movement?

Answer 4

As duration in hrs/day increases, the % efficacy of tooth movement decreases

Question 5

What deterioration can occur from orthodontic movement?

Answer 5

Root resorption

Pulpal changes

Pain and mobility

Loss of alveolar bone

Relapse of tooth position

Question 6

How do light forces move teeth?

Answer 6

Hyperaemia in the PDL in pressure side AND tension side

• Resorption of Lamina dura and osteogenesis matrix on the pressure side - osteoclasts
• apposition of osteoid on the tension side - osteoblasts
• remodelling of the socket via frontal resorption
• reorganisation of PDL

Question 7

How do moderate forces move teeth?

Answer 7

Occlusion of vessels of the PDL on pressure side
- cell free area (hylinisation)
- increased osteoclastic activity

Hyperaemia of vessels on tension side

Period of stasis

Increased endosteal vascularity - undermining resorption

Relatively rapid tooth movement with bone deposition on tension side

Healing of PDL

Question 8

Compression side =?

Answer 8

Osteoclasts

Question 9

Tension side =?

Answer 9

Osteoblasts