Cementum

Question 1

What cells produce cementum? How do these cells originate?

Answer 1

Cementoblasts, which originate from the mesenchymal cells of the dental follicle.

Question 2

What is the percentage chemical composition of cementum?

Answer 2

45% calcium hydroxyapatite, 33% organic material (collagen type 1 and GAGs) and 22% water

Question 3

What is the difference between primary and secondary cementum?

Answer 3

• Primary cementum is acellular (contains no cells), and is formed first. It covers the part of the root adjacent to the dentin. (cementum is formed from outside to inside)
• Secondary cementum is cellular. It contains cementocytes in lacunae. It covers the apical area overlying primary cementum.

Question 4

What are the two varying organic matrixes that can be present in cementum?

Answer 4

• extrinsic fibres > Sharpey fibres, which comes from the PDL and run the same direction to the fibres in it
• intrinsic fibres > cementoblasts, which run parallel to the root surface at right angles to Sharpey fibres

Question 5

What are the two main varieties of cementum in human teeth?

Answer 5

Acellular extrinsic fibre cementum (AEFC), which runs where primary cementum is found
Cellular intrinsic fibre cementum (CIFC), which runs where secondary cementum is found

Question 6

What are cementicles?

Answer 6

Small globular masses of cementum found on the roots of 35% of human teeth - possibly from trauma or tears in cementum or PDL

Question 7

What is the name for fusion of roots of adjacent teeth?

Answer 7

Concrescence

Question 8

What is the name for excessive production of cementum? When might this occur?

Answer 8

Hypercementosis, may occur following chronic periapical inflammation

Question 9

How might the cementum repair root fractures?

Answer 9

By the formation of cemental callus