(1) Anatomy and Histology of the Periodontium - cementum

Question 1

What is cementum?

Answer 1

thin layer of calcified tissue covering radicular dentine.

Question 2

How thick is cementum at the cervical?

Answer 2

10-15µm in thickness.

Question 3

How thick is cementum cervically?

Answer 3

50-200µm thick

Question 4

How thick could cementum be at the root apex?

Answer 4

600µm

Question 5

What does cementum adhere to?

Answer 5

Adheres to dentine and to the periodontal ligament.

Question 6

What is the name of the dentin at the root?

Answer 6

redicular dentin

Question 7

What cementum capable of doing?

Answer 7

repair and regeneration

Question 8

When is cementum formed?

Answer 8

Formed throughout life

Question 9

Can the cementum detach and reattach to the periodontal ligament?

Answer 9

allowing re- attachment of the periodontal ligament.

as it is formed throughout life

Question 10

What structure is cementum similar to?

Answer 10

bone

Question 11

What is the difference between bone and cementum composition?

Answer 11

Similar to bone in composition, but not innervated and avascular

Question 12

What colour is cementum?

Answer 12

pale yellow and has a dull surface

Question 13

Where can cementum be easily abraded?

Answer 13

cervically

e.g. gum recession can expose cementum

Question 14

What are the 2 types of cementum?

Answer 14

cellular
acellular

Question 15

What does cellular cementum contain?

Answer 15

cementocytes

Question 16

What does acellular cementum cover?

Answer 16

dentine

Question 17

Where is cellular cementum located?

Answer 17

apical area
inter-radicular areas overlying acellular cementum

Question 18

In general what cementum forms first?

Answer 18

acellular

closest to the dentin

Question 19

What type of section is this?

Answer 19

decalcified

see cells

Question 20

At what pace does cementum form?

Answer 20

slowly

Question 21

Name structures A-D and what do the black and white arrows point to?

Answer 21

A) Acellular cementum.
B) Cellular cementum. C) Pre-cementum.
D) Periodontal ligament.

White arrows point to cementocytes.

Black arrows point to cementoblasts.

Question 22

How do you define acellular cementum?

Answer 22

lines in it from slow growth

shown by A

acellular is always closest to the dentin

Question 23

How do you differentiate cellular and acellular cementum ?

Answer 23

the cellular cementum has cementocytes

shown by white arrows

Question 24

Where do cementocytes live?

Answer 24

in cellular cementum

Cementocytes live in the lacunae of cementum,

Question 25

What is C?

Answer 25

C = pre-cementum newly formed cementum, not calcified yet

Question 26

What is black arrow pointing to?

Answer 26

cementoblasts line the pre-cementum will form the cementum

Question 27

What happens when cementoblasts get trapped in their own secretion?

Answer 27

they become calcified and become cementocytes white arrow

Question 28

What section is this an example of?

Answer 28

ground section, cementocytes appear black in a ground section.

Question 29

What type of cementum is shown here?

Answer 29

cellular, decalcified

Question 30

What is the black substance here?

Answer 30

if there is a space, e.g. lacunae it will appear black due to the light reflection

Question 31

In cementum, what direction do the canaliculi of cementum face?

Answer 31

one direction both the cementoblasts and cementocytes

Question 32

What is a canaliculi?

Answer 32

a canaliculus is a small passageway

Question 33

Where do the nutrients for the cementocytes come from?

Answer 33

the periodontal ligament as the cementum and dentin are unvascularised and not inervated

Question 34

When the cementum become thicker and thicker, what do the cementocytes do?

Answer 34

they try to extend their processes through longer and longer canaliculi, which are projected in one direction. towards the periodontium

Question 35

What side is the periodontal ligament?

Answer 35

to the left tooth to the right shown by the direction of the canaliculi

Question 36

What is the most important function of cementum?

Answer 36

Attachment to the periodontal ligament?

Question 37

What type of section is this?

Answer 37

decalcified

Question 38

What type of cementum is attached to the periodontal ligament?

Answer 38

acellular

Question 39

Name structures A-C

Answer 39

A = enamel space (decalcified enamel) B= dentin C = acellular cementum (cervical so thin)

Question 40

Name structure A

Answer 40

periodontal ligament

Question 41

What is the periodontal ligament composed of?

Answer 41

principal fibres

Question 42

What do the fibres of the periodontal ligament connect?

Answer 42

the alveolar bone and the cementum

Question 43

What are the periodontal ligament fibres called when they insert into the alveolar bone?

Answer 43

sharpeys fibres

Question 44

How do the fibres of the periodontal ligament insert into the cementum?

Answer 44

precementum forms before it is calcified, the principal fibres insert into the cementum which later becomes fully calcified and anchors Sharpeys fibres into the cementum

Question 45

What side of the periodontal ligament has coarser sharpeys fibres?

Answer 45

the ones inserted into the alveolar bone

Question 46

Name structures A-C and the black and white arrows

Answer 46

decalcified section A = Dentine. B= Periodontal ligament. C= Alveolar bone White arrows point to acellular cementum. Black arrows point to Sharpey’s fibres in alveolar bone