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Craniofacial and Tooth Biology > 18. Dentine-Pulp Complex > Flashcards

18. Dentine-Pulp Complex Flashcards

1
Q

Define ‘dental pulp’

A

connective tissue derived from mesenchymal cells of dental papilla

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2
Q

2 types of dental pulp

A
  • coronal pulp
  • radicular pulp
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3
Q

Apical foramen and accessory canals are entry for …

A
  • blood vessels for nourishment
  • nerves for sensation
  • lymphatic vessels for lymph drainage
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4
Q

Dental pulp is … connective tissue made of …

A
  • loose
  • extracellular matrix
  • diff cell types
  • blood and lymphatic vessels
  • nerves
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5
Q

Dental pulp is …% water and …% organic material
Does this ever change?

A
  • 75, 25
  • changes in development (dental papilla to dental pulp) and varies between tooth types
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6
Q

Is there hard tissue in dental pulp?

A
  • none in normal pulp
  • calcifications and pulp stones occur in aged teeth
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7
Q

How different is pulp structure in primary and permanent teeth?

A

similar
- 4 zones in each

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8
Q

4 histological zones in pulp

A
  • odontoblast cell layer
  • cell-free zone
  • cell-rich zone
  • pulp core
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9
Q

Odontoblast cell layer contain what kind of cell?

A
  • odontoblasts
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10
Q

What’s within the cell-free zone?

A
  • few cells
  • mainly extracellular matrix
  • nerve endings
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11
Q

What’s within the cell rich zone?

A

many cells
- mainly fibroblasts

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12
Q

What’s within the pulp core?

A
  • central tissue
  • nerves
  • blood vessels
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13
Q

From innermost of pulp to outermost, order the layers

A
  • cell rich zone
  • cell free zone
  • odontoblast layer
  • predentin
  • mineralization layer
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14
Q

Cells within pulp

A
  • odontoblasts
  • fibroblasts
  • undifferentiated mesenchymal cells
  • stem cells
  • defence cells
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15
Q

Coronal odontoblasts are … and have what features?

A
  • columnar
  • cellular process into dentinal tubule
  • more cuboidal in root
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16
Q

Odontoblasts produce what? and for how long?

A
  • dentine (predentine)
  • present throughout life of tooth
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17
Q

As the tooth matures, what happens to odontoblast layer of pulp?

A
  • becomes flatter
  • number of cells reduced by apoptosis
  • secondary dentine laid at slow rate
  • reduces size of pulp
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18
Q

How does the odontoblast layer of pulp respond to external stimuli?

A
  • odontoblast-like cells can differentiate from progenitor cells in pulp
  • produces tertiary dentine
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19
Q

3 types of junctions between odontoblasts

A
  • tight
  • desmosomes
  • gap
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20
Q

Role of tight junctions and desmosomes in odontoblasts

A
  • maintains spacial relationships
  • restricts substances in pulp from entering dentine
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21
Q

Role of gap junctions in odontoblasts

A
  • openings allow exchange of small molecules and cell-to-cell communications
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22
Q

What is the most abundant cell type in dental pulp?

A

fibroblasts

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23
Q

Role of fibroblasts

A
  • produce collagen fibres and ground substance in pulp matrix
  • degrade collagen for collagen turnover
24
Q

Explain cellular differences in fibroblasts in young and old pulp

A
  • in young, large centrally located nucleus with multiple cellular processes
  • in aged, smaller, spindle shaped fibroblasts with fewer organelles
25
Q

Role of undifferentiated mesenchymal cells

A
  • differentiate into odontoblast-like cells and fibroblasts
  • number reduces with age
26
Q

Role of dental pulp stem cells

A
  • multipotent
  • can differentiate into odontoblasts, chondrocytes, osteoblasts, adipocytes and neurons
27
Q

Types and role of immune cells in dental pulp

A
  • macrophages patrol pulp and remove dead cells/bacteria with role in inflammation
  • T and B lymphocytes in adaptive/antibody driven immune system
  • neutrophils and eosinophils respond to infection and mediate inflammation
  • dendritic cells present foreign antigens to T cells
28
Q

What collagen is present in extracellular matrix of pulp?

A
  • type 1 and 3
  • forms a scaffold providing stability to pulp
29
Q

What’s in the ground substance/non-fibrous protein matrix of pulp?

A
  • glycosaminoglycans, proteoglycans, glycoproteins and water
  • hydrophilic molecules that swell when hydrated forming hydrogels that fill most of EC space
30
Q

Role of ground substance in extracellular matrix of pulp

A
  • resevoir for growth factors and other bioactive molecules
  • act as medium for transport and movement of nutrients/metabolites
  • regulates various cellular processes like proliferation, differentiation and migration
31
Q

Explain vascular supply of pulp

A
  • blood vessels originating in periodontal ligament enter pulp via apical foramen
  • peripheral blood vessels branch out towards odontoblast layer and form small capillaries
32
Q

Explain lymphatic drainage of pulp?

A
  • drain tissue fluid
  • thinner walls than blood vessels and have no red blood cells
33
Q

Around … nerve axons enter apical foramen

A

2500

34
Q

Of the nerve axons coming through the apical foramen, 25% are … and 75% are …

A
  • myelinated afferent nerve fibres
  • unmyelinated C fibres
35
Q

Explain myelinated afferent nerve fibres in teeth

A
  • Schwann cells (form myelin sheath)
  • transit pain sensation to CNS
  • cell bodies in trigeminal ganglion
36
Q

Explain unmyelinated C fibres in teeth

A
  • mainly devoid of Schwann cell covering
  • can sense changes in extracellular environment
  • afferent fibres (main) terminate at odontoblast layer or in dental tubules to transmit noxious stimuli (pain)
  • efferent fibres (minor) terminate on smooth muscle cells of arterioles to regulate capillary flow
37
Q

Explain the Plexus of Raschkow

A
  • extensive nerve plexus that terminates in the cell free zone just below the odontoblast layer of crown
  • no nerve plexus in root canals
  • some axons pass between odontoblasts and sometimes enter dental tubules
  • most nerve bundles terminate as free, unmyelinated nerve endings
38
Q

Function of the dental pulp

A
  • provide vitality to the tooth
  • nourishment of odontoblasts and other pulp cells via blood vessels/capillaries
  • protection with sensation of external stimuli (thermal, mechanical, chemical) via nerves/endings and barrier/defence (reaction to ext stimuli produces tertiary dentine and activation of immune system if inflamed)
39
Q

Changes in pulp chamber with age

A
  • young teeth have large pulp chamber
  • old teeth have very narrow pulp chamber and root canals
40
Q

How do the challenges for dentists change with young and old pulp chambers?

A
  • in young, the large chamber is a challenge for cavity/crown prep as it has a thin dentine layer and pulp exposure can occur easily
  • in old it challenges root canal treatment
41
Q

How is caries a spread of infection?

A
  • from dental pulp into surrounding periodontal tissues
  • causes periodontal abscess
42
Q

How is periodontal disease spread?

A
  • from surrounding periodontal tissues into dental pulp
  • e.g through accessory root canals
43
Q

Where are accessory root canals?

A
  • can occur anywhere in the root
  • mainly at root apex
44
Q

What’s an common cause of root canal treatment?

A
  • failure to notice and clean accessory root canals
  • causes persistant infection
45
Q

Procedure of root canal

A
  • infected tooth
  • drill an opening
  • fill and clear
  • finish off
46
Q

Collagen fibres are more towards … so it’s easier to do a pulpectomy from …

A
  • tooth apex
  • apical region
47
Q

Define ‘diffuse calcifications or pulp stones’

A
  • calcified masses can be formed in pulp
  • as a response to chronic stimulus (caries infection etc) or age related change
48
Q

How do pulp stones occur?

A
  • older pulp becomes less vascular and can form diffuse calcifications
  • false pulp stones formed from calcifying blood vessels and contain bone-like material (organised in concentric rings)
  • true pulp stones fromed from detached odontoblasts and contain dentine
  • pulp stones attached to dentine or remain free in pulp
49
Q

Afferent nerve endings terminate where?

A
  • in dentine/near odontoblasts
50
Q

Afferent nerve endings sense?

A
  • pain
  • mechanical
  • chemical
  • thermal
    stimuli
51
Q

3 theories for dentine sensitivity

A
  • neural
  • odontoblasts as receptors
  • hydrodynamic
52
Q

Explain neural dentine sensitivity

A
  • dentine is directly innervated
  • but not many nerve endings are detected in dentine
53
Q

Explain odontoblasts as receptors dentine sensitivity

A
  • odontoblasts act as receptors
  • form synaptic contacts with nerve endings
54
Q

Explain hydrodynamic theory

A
  • fluid movement in dentinal tubules is sensed directly or indirectly by nerve endings
55
Q

What is thought to increase sensory capacity?

A

branching of odontoblast processes at EDJ

Craniofacial and Tooth Biology (25 decks)

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