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Restoration and Maintenance of Oral Health > Endo: Dentine-Pulp Complex > Flashcards

Endo: Dentine-Pulp Complex Flashcards

1
Q

What is formed from the ectoderm?

A

Enamel

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2
Q

What is formed from the Neural crest derived ectomesenchyme?

A

Dentine-pulp complex

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3
Q

Name the 3 stages of tooth development

A
  1. Bud stage
  2. Cap stage
  3. Bell stage
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4
Q

What happens in the bud stage?

A

Assumes shape of a bud from the folding of of the epithelium from the dental lamina proliferating into the ectomesenchyme

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5
Q

What happens in the cap stage?

A

Assumes the shape of a cap

Further epithelial proliferation gives rise to enamel organ

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6
Q

What happens in the bell stage?

A

Shape of a bell
Invagination/folding deepens - dental papilla contained within this leads to formation of dentine-pulp complex

2 cell layers facing each other have different fates - inner layer = ameloblasts
outer layer = odontoblasts; initiate dentine deposition

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7
Q

What induces and controls differentiation of odontoblasts and cementoblasts?

A

Hertwig’s epithelial sheath

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8
Q

What does Hertwig’s epithelial sheath do? (3)

A

Guides and initiates root formation
Signals odontoblasts and cementoblasts to differentiate
Further differentiation = perio support structure forms

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9
Q

What happens following the bell stage of tooth formation?

A

cells of inner and outer enamel epithelium merge to form cervical loop = root formation begins at CEJ

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10
Q

How does the cementum attach to the perio support structure?

A

through Sharpey’s fibres

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11
Q

What allows the bone to anchor to the periodontal fibres?

A

The outer layer of the dental sac

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12
Q

What is the composition of dentine (& percentages)?

A

70% hydroxyapatite (mineral)
20% organic matrix (collagen - mostly type 1, some type 5)
10% water

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13
Q

What type of collagen mostly makes up the organic matrix of dentine?

A

type 1

type 5 is minor

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14
Q

Give examples of growth factors or enzymes that are present and embedded in the dentine (5)

A 
TGF-B: transforming growth factor 
PDGF: Platelet-derived growth factor 
IGF: insulin-like growth factor 
BMPs: bone morphogenic proteins 
MMPs: matrix-metalloproteinases
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15
Q

When are the enzymes and growth factors released from the dentine?

A

They are released during demineralisation and triggers dentinal reparative events

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16
Q

What constitutes the largest part of tooth structure?

A

Primary dentine

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17
Q

Primary dentine is deposited by what and at what rate per day?

A

Deposited by odontoblasts

at 4 micrometres per day

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18
Q

What are the 2 sub-categories of primary dentine?

A

Mantle

Predentine

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19
Q

Which subcategory of primary dentine is formed first and is closest to the enamel/cementum?

A

Mantle

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20
Q

Describe the subcategory of primary dentine: predentine

A

10-40 micrometre layer of dentine undergoing completion of it’s mineralisation.

Located between odontoblast layer and mineralised dentine; and moves towards centre during secondary dentine deposition

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21
Q

Describe secondary dentine

A

deposited by odontoblasts AFTER root formation and throughout the life of the tooth (explains progressive reduction of the root canal space)

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22
Q

What type of dentine is laid down in response to an external stimuli?

A

tertiary

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23
Q

Name the 2 types of tertiary dentine

A

Reactionary

Reparative

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24
Q

Outline reactionary tertiary dentine

A

Odontoblast insult not severe and odontoblast layer survives.

Still has continuous tubular structure (like primary and secondary dentine)

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25
Q

Outline reparative tertiary dentine

A

Severe insult to odontoblast layer
Pulpal stem cells recruited and differentiate into odontoblast-like cells.

Tubules NOT present or continuous

26
Q

What type of dentine is characterised by enhanced mineralisation of the intratubular/peritubular dentine?

A

Sclerotic dentine

27
Q

How are dentine tubules formed?

A

During primary and secondary dentinogenesis.

Odontoblast mineralisation front moves towards centre

28
Q

Describe odontoblasts and how they interact with the tubules

A

They are columnar cells with polarised processes that leave imprints on newly formed dentine

> cytoplasmic processes projected into dentinal tubules

29
Q

Which dentine is more calcified - intra tubular dentine or inter tubular dentine?

A

Intratubular

30
Q

Where would you find intratubular dentine and intertubular dentine?

A

Intra/peritubular dentine - inner part of tubule

Intertubular - between dentine tubules

31
Q

Which type of dentine makes up the most of the dentinal structure?

A

Intertubular dentine

32
Q

What is the diameter(s) of the dentine tubules?

A

2.5 microm by the pulp

1 micro m by the enamel/cementum

33
Q

Is the dentine more or less dense near the pulp?

A

More dense

higher density

34
Q

What is contained within dentinal tubules? (5)

A
  1. Dentinal fluid
  2. Odontoblastic processes
  3. Nerve fibres
  4. Type 1 collagen
  5. Ground substance (glycoproteins, proteoglycans, glycosaminoglycans)
35
Q

What are the 2 important structures that the tubular structure provides to dentine?

A

Permeability

Sensitivity

36
Q

Dentine permeability varies in different areas - does this increase or decrease towards the pulp chamber?

A

Increases progressively

37
Q

How does dentine sclerosis affect the permeability of dentine tubules?

A

It makes them less permeable

38
Q

What is considered as the main mechanism for dentinal sensitivity and hypersensitivity?

A

Hydrodynamic theory

39
Q

What is the mechanism behind the hydrodynamic theory of dentine sensitivity?

A

Rapid displacement of dentinal fluid in tubules deforms odontoblast processes and activates A-delta fibres, leading to transfer of nociceptive signal

40
Q

What can trigger dentinal fluid movement?

A

Temperature (hot and cold)
Osmolarity (e.g. sweet)
Mechanical pressure (e.g. chewing, probing)

41
Q

What are the 4 functions of the pulp?

A
  1. Nociception (painful,injury) : sense harmful stimuli
  2. Proprioception (ability to sense movement, action, and location) & sensitivity: sense own position related to pressure = warning mechanism
  3. Defence: prevents systemic spread of dental infection by inducing foreign body response. Immunocompetent - can induce dentine formation
  4. Formative: produces dentine > forms coronal & radicular structure during odontogenesis
42
Q

What are the components of the pulp? (4)

A

It is a connective tissue composed of different type of cells, extracellular connective matrix (fibres and ground substance), blood vessels and nerves

43
Q

What are the main cell lineages in the pulp? (5)

A

Odontoblasts, mesenchymal stem cells, fibroblasts, Schwann cells, defence cells (antigen presenting cells, macrophages, lymphocytes)

44
Q

Describe the shape of the odontoblasts at:

  1. The crown
  2. The root
A
  1. Columnar

2. Cuboidal

45
Q

How are odontoblasts organised?

A

They are organised into a single layer of cells (odontoblastic layer) facing predentine.

46
Q

Odontoblast cells are polarised - what does this mean?

A

The nuclei are localised towards the pulp.
Mitochondria-rich area is closer to predentine and localised at formative (developing) end before the cytoplasmic/odontoblastic projection

47
Q

Where are the pulpal stem cells?

A

They are scattered amongst the pulp but are mostly localised in cell-rich area

48
Q

Which cell lineage is the most abundant in the pulp?

A

Fibroblasts

49
Q

What do the fibroblasts produce?

A

They produce the extracellular matrix (glycosaminoglycan, proteoglycans, glycoprotein), representing the medium of signals and nutritive substance

50
Q

The pulpal blood supply is provided by vessels that enter from where?

A

The apical foramen and lateral canals

51
Q

What vessels are involved in the vascularisation of pulp?

A

arterioles, capillaries, venules, arteriovenous shunts, lymph vessels

52
Q

Which blood vessels enter the root canal and follow the long axis of the root?

A

Arterioles

53
Q

What branch off the arterioles towards the odontoblastic layer (which represents the vascular zone adjacent to the cell-rich zone)?

A

Capillaries

54
Q

Where are venules present?

A

Venules are present towards the centre of the pulp

55
Q

What is the purpose of the arteriovenous and venous-venous shunts in the vascularisation of pulp?

A

They control the microcirculation

56
Q

Pulpal blood flow is relatively high compared to other cranial tissues - what may this favour?

A

It may favour a wash out effect of irritants

57
Q

What is the self-strangulation theory of the pulp?

A

The hard case around the pulp, in the case of inflammation, can lead to pulpal hypoxia

58
Q

What nerve innervates the pulp?

A

Maxillary and mandibular branches of the trigeminal nerve

59
Q

Is an autonomic (involuntary) component present in the pulp?

A

Yes

60
Q

Among the nerve fibres reaching the pulp - what percentage are unmyelinated and myelinated, and what type are they?

A

80% unmyelinated C fibres

20% myelinated A fibres

Restoration and Maintenance of Oral Health (29 decks)

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