Oral Biology

Question 1

Key features of enamel

Answer 1

• Resists abrasion
• Brittle
• Supported by dentine
• Varies in thickness
• Translucent - increasing with mineralisation

Question 2

What enamel cover?

Answer 2

Tooth crown

Question 3

Enamel content

Answer 3

• Hydroxyapatite - 95% Mass
• Water 💧- 4% Mass
• Organic matrix - 1% Mass (Enamelins, Amelogenins, Peptides, Amino acids)

Question 4

Content of Dentine

Answer 4

• Hydroxyapatite - 70% Weight
• Water - 10% - Weight
• Organic matrix - 20% Weight

Question 5

Who forms the bulk of the tooth ?

Answer 5

Dentine

Question 6

Contents of dentinal tubules

Answer 6

Odontoblast process
Unmyelinated nerve terminals (Sensory)
Dendritic cells
Dentinal fluid / ECF - from pulp

Question 7

Pulp content

Answer 7

• CellsOdontoblasts, fibroblasts, defence cells
• Extracellular componentsFibres (Collagen, oxytalan)Matrix (Proteoglycans, chondroitin SO4, dermatan SO4)
• NervesSensory; autonomic (Sympathetic)
• Blood vessels & Lymphatics

Question 8

Function of the pulp

Answer 8

Dentine growth & Repair

Defence - immune cells and lymphatics

Neural - Sensory, control of dentinogenesis

Question 9

Who covers root of dentine?

Answer 9

Cementum

Question 10

Where Cellular cementum present in the tooth?

Answer 10

In apical part of the root and furcation regions

Question 11

Where acellular cementum present in the tooth?

Answer 11

Usually adjacent to dentine

Question 12

Who form primary and secondary form of cementum?

Answer 12

Primary cementum—> acellular cementum

Secondary cementum—> cellular cementum

Question 13

Where cementocytes are found ?

Answer 13

Cellular cementum

Question 14

A is?

Answer 14

Acellular cementum

Question 15

Where Sharpey’s fibres present?

Answer 15

Present in acellular extrinsic fibre cementum - 2/3 of root

Question 16

Role of periodontal fibres - Sharpey’s fibres

Answer 16

anchored to the cementum of the tooth and the alveolar bone.

Question 17

Where, in the tooth, enamel is thickest?

Answer 17

Incisal or cuspal region

Question 18

Where, in the tooth, enamel is thinnest?

Answer 18

At the cervical region

Question 19

What is the name of these fine lines running all the way from the EDJ to the surface of the tooth?

Answer 19

These represent the enamel rods

Question 20

What are the thicker brownish lines, that run obliquely from the outer surface to the EDJ?

Answer 20

Striae of Retzius

Question 21

The cross striations present in enamel rod are about 0.004mm (4 µm) apart. Assume that the maximum thickness of enamel is 2.5 mm at the tip of a cusp (2.5 mm = 2,500 micrometres). How long will it take to lay down the full thickness of enamel in a permanent tooth?

250 days
250 week
125 days
625 days.

Answer 21

625 days

Question 22

What can accumulate here and facilitate the beginning of caries?

Answer 22

Plaque

Question 23

A number of structures are present within dentinal tubules. Cell processes from which cell can be found on dentinal tubules near the pulp?

Cementoblasts
Fibroblasts
Odontoblasts
Oligodendrocytes

Answer 23

Odontoblasts

Question 24

Some tubules may also contain nerve terminals which are:

Myelinated
Unmyelinated

Answer 24

Unmyelinated

Question 25

A few tubules may contain dendritic cells (part of the immune system). Are the processes from odontoblasts, nerves and dendritic cells found all the way along the dentinal tubules? Yes No Sometimes

Answer 25

No

Question 26

Where dentinal tubules are closer together? Inner Outer

Answer 26

Inner dentine

Question 27

Where dentinal tubules are larger? Inner Outer

Answer 27

Inner dentine

Question 28

How cells are organised on a pseudostratified cell layer?

Answer 28

They have a single layer In a pseudostratified cell layer the nuclei are irregularly placed, giving the appearance of several cell layers.

Question 29

Name another structure where you have seen a pseudostratified columnar cell layer. Ciliated columnar epithelium of trachea Skin Vascular endothelium

Answer 29

Ciliated columnar epithelium of trachea

Question 30

Cementum is important because it can: compensate tooth wear by growing reinforce the weak dentine shrink and compensate excessive dentinal growth

Answer 30

compensate tooth wear by growing

Question 31

What is the function of tertiary dentine? Protective Inflamatory Degenerative

Answer 31

Protective

Question 32

How oral fluids have a protection function?

Answer 32

Cleansing Mucosal protection Buffering Remineralisation Antimicrobial

Question 33

What are the functions of these oblique periodontal ligament fibres? 1-Avoid movement of the tooth 2-Compress the tooth into the socket 3-Suspend the tooth within the socket 4-Resist biting force

Answer 33

3-Suspend the tooth within the socket 4-Resist biting force

Question 34

Recall the types of tissues you observed in the histology classes. How would you classify the periodontal ligament? Nervous tissue Muscle tissue Connective tissue Epithelial tissue

Answer 34

Connective tissue

Question 35

Relative to the tooth and bone, in which direction do the periodontal ligament fibres run? From the bone to insert more apical into the enamel From the bone to insert more cervical into the cement From the bone to insert more cervical into the enamel From the bone to insert more apical into the cementum

Answer 35

From the bone to insert more apical into the cementum

Question 36

You will be able to see some glands in the lamina propria and deep to that are some muscle layers. This glands are: Exocrine Endocrine

Answer 36

Exocrine Those are minor salivary glands

Question 37

Recalling the histology microscopy class on muscle tissues, what type of muscle is present deep to the glands? Skeletal Smooth

Answer 37

Skeletal The fibres are wide in diameter, and display multiple, peripherally placed nuclei. The muscle is probably the buccinator, which tenses the cheek during eating.

Question 38

These glands in the palate are: Mucous Serous

Answer 38

Mucous You can see the typical characteristics of a mucous secreting minor salivary gland

Question 39

Recall the main histological differences between serous and mucous gland cells. What are the main histological differences between serous and mucous gland cells? Serous cells: flattened nuclei at the outer aspect of the cell cell nuclei are in centre of cell stain pink with H&E ‘foamy’ cytoplasm

Answer 39

cell nuclei are in centre of cell stain pink with H&E

Question 40

Recall the main histological differences between serous and mucous gland cells. What are the main histological differences between serous and mucous gland cells? Mucous cells: Fattened nuclei at the outer aspect of the cell cell nuclei are in centre of cell stain pink with H&E ‘foamy’ cytoplasm

Answer 40

Fattened nuclei at the outer aspect of the cell ‘foamy’ cytoplasm