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 % efficiency of tooth movement increases then plateaus

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

What occurs in light forces when moving a tooth?

Answer 6

Force causes hyperaemia in blood flow to PDL

Osteoclasts then appear on pressure side and osteoblasts on the tension side.

Osteoclasts resorb lamina dura on pressure side while osteoblasts lay down osteoid matrix on the tension side in the new PDL space

This is frontal resorption

Question 7

What occurs when moderate forces act on a tooth?

Answer 7

Increased force causes occlusion of blood vessels on the pressure side and hyperaemia of vessels on the tension side

Cell free areas on pressure side due to increased pressure (hyalination)

Period of Stasis followed by increased vascularirty on underside of bone supporting tooth leads to a sudden move in the desired direction.

Question 8

What occurs with heavy forces On a tooth?

Answer 8

Occlusion of blood vessels leading to necrosis of PDL and bone occurs, areas of cell free hyalination areas occur and also resorption of root surface