Dental Hard Tissue

Question 1

What is are the two categories of periodontal tissue?

List 4 dental tissue for each category.

Answer 1

Mineralised/hard: alveolar bone, cementum, dentine, enamel

Non-mineralised/soft: oral mucosa, dental pulp, gingiva, periodontal ligaments

Question 2

Which one of the 8 types of periodontal tissue can provide stem cells which differentiate into mineralised bone?

Answer 2

PDL

Question 3

Composition of dentine (in percentages)?

Answer 3

70% Inorganic mineral salts (mainly HA in collagen matrix) + 20% Organic substance (protein)+ 10% H2O

Question 4

Non-collagenous proteins include… (6)

Answer 4

Non-collagenous proteins include: DSPP, proteoglycans, gla-proteins, acidic proteins, growth factors, lipids

Question 5

What does DSPP stand for and what is its function (2)?

Answer 5

Dentine sialo phosphoproteins ; Regulates crystal growth and mineralisation of collagen fibres within ECM

Question 6

What tissue forms the bulk of the teeth?

Answer 6

Dentine

Question 7

What is the colour of dentine

Answer 7

yellow

Question 8

Major feature of dentine?

Answer 8

Dentinal Tubules

Question 9

Dentinal tubules are h…. and have processes of cell bodies (o………).

Answer 9

Hollow

Odontoblasts

Question 10

What cells stimulate ameloblasts?

Answer 10

Odontoblasts

Question 11

What makes dentine permeable?

Answer 11

The hollow structure of the tubules within the collagenous matrix

Question 12

what are Shreger Lines/Primary curvatures?

Answer 12

Sigmoidal/S Shape of dentinal tubules

Question 13

Where are odontoblast cell bodies located (what junction)? Above or below pre-dentine?

Answer 13

DPJ - dentine-pulp junction

Just below

Question 14

Function of dentine (4)

Answer 14

• Vital tissue
  
  • Sensitive to stimuli
  • Act as “shock absorber”, dissipating large
    loads/forces throughout tooth structure; highly
    elastic
  • Formed throughout life of tooth

Question 15

Hardest to least hardest out of…

• Enamel
• Dentine
• Bone
• Cementum

Answer 15

Enamel
Dentine
Bone and Cementum

Question 16

3 types of dentine and define each type

Answer 16

Primary= Formed prior to apical completion; more formed rapidly and mineralised than 2nd
Secondary=formed post root completion; more slowly formed and less mineralised than 1st
Tertiary= formed as a result of injury; irregular pattern of tubules and produced by local cells in area of trauma/stimulus

Question 17

Which type of dentine are circumpulpal, pertiubular, intratubular, mantle dentine from? And define each

Answer 17

Primary Dentine
Peritubular: located in walls of tubules; highly calcified
Intratubular: located between tubules; highly calcified
Mantle: Outermost layer of 1st
Circumpulpal: located around the pulp, uniform structure except around the edges

Question 18

Which type of dentine makes up the bulk of dentine? (1/2/3 and what specifically)

Answer 18

Primary, circumpulpal

Question 19

Two types of tertiary dentine and definitions

Answer 19

○ Reactionary: derived from pre-existing dentine

○ Reparative: derives from newly odontoblasts (created pulpal progenitor cells)

Question 20

Define sclerotic, translucent and dead tracts

Answer 20

• Translucent: caused as of ageing tubules, blocked via peritubular, more pronounced at the root apex
• Sclerotic: occlusion/blocking of tubules caused via external stimulus (similar to translucent but linked with stimulus NOT formed by odontoblasts)
• Dead tracts: odontoblasts killed by external stimulus; leaving hollow tubules which can then be filled with sclerotic. Appear dark under microscope

Question 21

What are Lines of Von Ebner and are they linked with dentine or enamel?

Answer 21

Dentine Linked

show cyclic activity of odontoblast during dentine formation

Question 22

What are Schreger Lines (primary curvature) and are they dentine or enamel linked?

Answer 22

Dentine Linked

tubules following sigmoid route

Question 23

How are dentine and enamel linked?

Answer 23

Dentine must be present for enamel formation; ameloblasts must be present for dentinogenesis to continue

Question 24

Does enamel harden and mature before or after tooth eruption?

Answer 24

Before

Question 25

Where is enamel the thickest?

Answer 25

Cuspal/Incisal region

Question 26

What colour is enamel?

Answer 26

Translucent but it can vary from light yellow to greyish/blue white

Question 27

What do teeth appear whiter in primary dentition than in permanent dentition?

Answer 27

Primary Dentition has more opaque crystalline form therefore appear whiter than permanent dentition

Question 28

Why does enamel appear yellower as a person ages?

Answer 28

Enamel gets thinner over time as of wear and so dentine (which is yellow) becomes more visible.

Question 29

Functions of enamel (4)

Answer 29

Mastication
Aesthetic
Protective
Dissipation of forces

Question 30

Composition equation of enamel

Answer 30

96-97% Mineral Salts (HA, F-, carbohydrates) + 3-4% Organic substance (fibrillar matrix)

Question 31

What is the structure of enamel composed of (3)?

They are visible under light microscopes

Answer 31

Enamel Rods (prism)
Rod sheaths - Distinct thin layer peripheral to the rods
inter-rod substance (cement)

Question 32

What are Striae of Retzius and are they linked with dentine or enamel?

Answer 32

Enamel linked
Dark lines form DEJ towards surface of tooth, form because of weekly rhythm of enamel production causing structural alteration of rods, 4micrometer intervals

Question 33

What are Bands of Hunter and Schreger and are they enamel or dentine linked?

Answer 33

Enamel

Optical phenomena caused by changing orientation of adjacent rods

Question 34

What is gnarled enamel and is it enamel or dentine linked?

Answer 34

Enamel
Are like a geological fault, project from the DEJ for a short distance into the enamel contain greater concentration of enamel than the rest of the enamel

Question 35

What is perikymata and is it dentine or enamel linked?

Answer 35

Enamel
Enamel lamella, wave like transverse groves, external incremental lines of retzius, project from DEJ for short distance into enamel - No clinical significance