Histology - Functions of the PDL

Question 1

What are the main functions of the PDL

Answer 1

Acts as connective tissue, resisting detachment of tooth protects nerves & vessels
Cells maintain + remodel adjacent bone and cementum
Acts as mechanoreceptors
Acts in maintaining tooth in its place stopping mesial drift

Question 2

What tooth movements occur doing mastication

Answer 2

Unloaded tooth
- small pulsatile movements (in sync with heartbeat)
Initial load           
- elastic phase (rapid intrusion) 
Prolonged load     
- creep phase (slow intrusion)
Initial load removed
- elastic phase
Prolonged removal
- creep phase
Elastic phase + creep phase = visco elastic phase

Question 3

Describe the initial function of the PDL

Answer 3

At first it was though as a load is applied to tooth and due to the tension in the fibres increases crests are pulled together

Question 4

What is failure stress strain?

Answer 4

When a point is reached when damage occurs to the tissue and it will never go back to OG shape

Question 5

Why is failure stress strain of PDL surprising?

Answer 5

The failure stress strain (20%) is similar to that of foetal fibres surprising as large loads are applied during mastication (Loading occurs without damage to ligament)

Question 6

Describe fluid flow

Answer 6

Load is dissipated by fluid in the PDL, when load is applied the fluid is pushed downward and apart increasing the distance between Crestal regions (Compression)