Cementum and Tooth Movement

Question 1

Notable Features Of Cementum

Answer 1

• supportive function via attachment to sharpey’s fibers of PDL
  will resorb in cases of stress caused by traumative occlusion or overly aggressive tooth movement during orthodontics
  normal physiologoical cemental/root resorption occurs during exfoliation f primary teeth and permanent tooth eruption
• unique hard tissue with ability to resorb and later to rebuild (sim to bone and dentin)
• cementum more resistant to resorption than bone
  scalloping occurs during aging, cemental spikes formed

Question 2

Physiologic Tooth Movement

Answer 2

• Tooth eruption
• repositioning of teeth due to facial growth and tooth related factors
  
  • -> increased arch size
  • -> accomodation of occlusal forces
  • -> “mesial drift” of teeth after tooth loss or hyper eruption

Question 3

Orthodontic Movement

Answer 3

only possible if tooth resorption occurs on the side the

• pressure on the side of the direction of tooth
• tension within the PDL

Bone resorption on the surface of the lamina dura

Compression changes on the PDL ONLY
Tension changes on the PDL, BONE and CEMENTUM

Question 4

What happens if compression is too great or too rapid?

Answer 4

hyalinization of the PDL (Vascularity is excluded and ligament appears colorless.

Question 5

What is required for bone removal?

Answer 5

compression
allows osteoclasts to organize from monocytes
organization happens within a few hours after tooth movement.

Question 6

Where does bone resorption occur?

Answer 6

bony surface of socket, cementum or root surface or both.

Question 7

Can resorption be reversed?

Answer 7

YES

• by deposition of bone or cementum within the area of resorption
• area where deposition occurs is called the “reversal line”

Question 8

What is required for bone deposition?

Answer 8

• tension

- fibroblasts, osteoblasts, cementoblasts from mesenchymal cells

Question 9

Fibroblasts

Answer 9

colagen renewal

Question 10

osteoblast

Answer 10

synthesize bone proteins producing osteoid and then mineralize the bone matrix

Question 11

Where does deposition occur?

Answer 11

along alveolar and cemental surfaces around stretched perforating fibres
Finger like projections of bone follow path of tooth movement