Tooth Movement

Question 1

4 main cell types of the PDL

Answer 1

1) Fibroblasts
2) Cementoblasts
3) Osteoblasts
4) Osteoclasts

Question 2

Fibroblasts

Answer 2

Responsible for producing and degrading the PDL fibres

Question 3

Cementoblasts

Answer 3

Responsible for producing cememtum

Question 4

Osteoblasts

Answer 4

• Responsible for bone production and the co-ordination of bond deposition and resorption
• Recruits and activates osteoclasts
• Main regulators of bone homeostasis

Question 5

Osteocytes

Answer 5

• When osteoblasts become surrounded by newly formed mineralized bone they become osteocytes
• Thought to be responsible for detecting mechanical load on the bone
• Communicate and sense mechanical stress through their canaliculi extensions

Question 6

Osteoclasts

Answer 6

Responsible for bone resporption

Question 7

Bone Homeostasis

Answer 7

The balanced and continuous process of bone remodeling around moved teeth, bone formation and resorption is balanced

Question 8

Undermining resorption

Answer 8

• A delayed bone remodeling process that occurs when heavy, excessive force is applied to a tooth, compressing the periodontal ligament to the point where blood flow is cut off
• Osteoclasts arrive from adjacent undamaged areas to removed the alveolar bone that borders the necrotic zone -this is “undermining” the compressed areas
• Delayed tooth movement 10-14 days
  Associated with greater pain

Question 9

What causes Hyalinization?

Answer 9

When heavy force is applied, the compressed zone of PDL becomes filled with dead, non-cellular tissues

Question 10

Frontal Resorption

Answer 10

• A desirable process as it allows for smooth, slow and continuous tooth movement with minimal discomfort
• A direct result of applying light, continuous forces that do not completely occlude the blood supply to the PDL
• The bone removal occurs directly at the site of pressure, on the surface of he lamina dure(the bone lining the tooth socket) facing the applied force

Question 11

Odontoclasts

Answer 11

Cells responsible for the removal of cementum and dentine

Question 12

Root resorption

Answer 12

• Inflammatory response when moving teeth
• Occurs in most patients undergoing orthodontic treatment
• Cells responsible are odontoclasts

Question 13

Key point with tooth movement

Answer 13

Orthodontic treatment would no be possible without the ability of the alvelop bone to remodel

Question 14

Average root resorption during ortho tx

Answer 14

1-2.5mm

Question 15

Optimal force level for Intrusion

Answer 15

15-25g

Question 16

Optimal force level for Tipping

Answer 16

50-75g

Question 17

Optimal force level for Extrusion

Answer 17

50-100g

Question 18

Optimal force level for Root uprighting

Answer 18

75-125g

Question 19

Optimal force level for Bodily movement

Answer 19

100-150g