Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Oral Biology > Tooth Development III - Dentinogenesis > Flashcards

Tooth Development III - Dentinogenesis Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What are Odontoblasts?

A
  • Dentine forming cells
  • Derived from Ectomesenchymal cells
  • Tall, columnar shape and establish a continuous single layer with a clear epithelioid appearance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the two stages of Odontoblast differentiation?

A
  1. Epithelial-mesenchymal interactions

2. Odontoblastic cytodifferentiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the Epithelial-Mesenchymal Interactions?

A
  • Induction signals from the ectodermal epithelium cause changes in the composition of the basement membrane of the internal enamel epithelium
  • Growth factors are expressed within the Internal Enamel Epithelium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Cytodiffereniation of Odonoblasts: What happens during this process?

A
  • Differentiation of the odontoblasts begins with the Dental Papilla cells adjacent to the deepest invagnination(s) of the Internal Enamel Epithelium
  • Differentiation starts a the cusp tip or incisal edge
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Cytodiffereniation of Odonoblasts: What happens to the Papilla cells?

A
  • Hypertrophy of the Pre-odontoblasts
  • Nuclei move away from the enamel organ; towards the basal part of the cell
  • Re-arrangement of the cytoskeleton
  • Small cell processes extend from the odontoblast - directed towards the basement membrane of the Internal Enamel Epithelium
  • Number of processes reduces and one large one dominates
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Cytodifferentiation of Odontoblasts: How do the newly differentiated cells bind to one-another and communicate?

A
  • Smaller processes remain and link Odontoblasts to each other and to underlying cells in the pulp
  • Cell-to-cell junctions increase in number
  • Tight/Gap/Desmosomes junctions occur and allow for some signalling that coordinate the activities of the Odontoblasts
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Deposition of Dentine Matrix: How does this process occur?

A
  • Once fully differentiated, Odontoblasts secrete its organic matrix
  • Collagen type I is the most prevalent component
  • Dentine Phosphoprotein (DPP) is the 2nd most abundant protein
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What’s the function of Dentine Phosphoprotein?

A
  • Role in mineralisation and in Epithelial-mesenchymal signalling
  • Also secreted by Pre-ameloblasts
  • Secreted form Odontoblastic process a short distance form the cell body
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What’s the first layer of Dentine laid down?

A

Mantle Dentine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What’s Mantle Dentine?

A
  • Only at periphery of the tooth in the Coronal region
  • Type I collagen fibres that are laid down initially lie at right angles to the future Dentine-Enamel Junction
  • Cell budding to form matrix vesicles occurs in mantle dentine
  • Membrane-bound organelles containing ALKALINE PHOSPHATASE are formed leading to a concentration of phosphate ions within the vesicles and the development of crystals
  • Less mineralised and consequently resilient
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What’s the next layer of Dentine?

A
  • Circumpulpal Dentine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What’s Circumpulpal Dentine?

A
  • Bulk of Dentine
  • Thin at initial stages of Dentinogenesis; becomes thicker continuously at the expense of the space initially occupied by pulp
  • NOT A HOMOGENOUS LAYER
  • Most prominent part of the dentine is formed by INTERTUBULAR DENTINE
  • PERITUBULAR DENTINE is found around the lumen of the tubules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How is calcium controlled within Circumpulpal Dentine?

A
  • Odontoblasts control the transport and release of calcium ions
  • Calcium is concentrated in organelles at the distal end
  • Deposited onto a template formed by collagen I fibrils; becoming a crystalline mineral
  • Controlled by DPP
  • DPP is highly anionic and thus can bind calcium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What happens if there are high levels of DPP?

A
  • Crystal formation is inhibited

- Odontoblasts control mineralisation by controlling DPP concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What happens if a conformation change occurs with DPP?

A
  • Allows DPP to bind more calcium ions; leading to the formation and growth of crystals
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Where do the crystals appear first within Circumpulpal Dentine?

A
  • Hole zone formed by quarter stacking of collagen
17
Q

What’s DPP’s role in mineralisation?

A
  • Transport of calcium ions to the mineralisation front
  • Location of nucleation to specific regions on the collagen fibrils
  • Stabilisation of the crystals
18
Q

What’s the mineralisation front in Dentine?

A
  • Area of mineralisation; boundary between unmineralised and mineralised Dentine
  • Appears irregular
  • Linear or spherical or a combination
  • Calcospheres fuse, if not completely interglobular dentine will form
19
Q

Later Dentines Formation: What’s Intratubular Dentine and how is it formed?

A
  • Small crystals in amorphous matrix (glycoproteins, lipids, bone sialoprotein)
  • The main Odontoblastic processes are surrounded by intratubular dentine
20
Q

Later Dentines Formation: What’s Secondary Dentine and how is it formed?

A
  • A programmed age change in Dentine
  • Apoptosis of Odontoblasts as the pulp volume decreases
  • Leads to a change in tubular direction
21
Q

Later Dentines Formation: What’s Tertiary Dentine?

A
  • Low grade stimuli to the pulp induce the proliferation of Tertiary dentine
  • The tubules can be: Tubular/atubular/irregular
  • The pulp doesn’t respond to stimuli by increasing the rate of deposition of secondary dentine but by inducing previously quiescent odontoblast-like cells to produce mineralised tissue
22
Q

What’s Interglobular dentine?

A
  • Dentine mineral is deposited as globules or calcospherites
  • These can fuse to form a uniformly calcified tissue

HOWEVER

  • Sometimes, (usually beneath mantle dentine/granular layer) the fusion is incomplete
  • Give a TREE CANOPY APPEARANCE
23
Q

What’s the Granular layer?

A
  • Periphery of dentine in the root; presence of a dark granular zone
  • In these areas the dental tubules in this area branch more profusely and loop back on themselves - creating air spaces in ground sections
  • Layer is hypomineralised in comparison to circumpulpal dentine
24
Q

What’s the Hyaline layer?

A
  • Obscure origin
  • Narrow band which is non-tubular and relatively structureless
  • MAY serve as a bond between cementum and dentine

Oral Biology (33 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions