18. Dentine-Pulp Complex Flashcards
1
Q
Define ‘dental pulp’
A
connective tissue derived from mesenchymal cells of dental papilla
2
Q
2 types of dental pulp
A
- coronal pulp
- radicular pulp
3
Q
Apical foramen and accessory canals are entry for …
A
- blood vessels for nourishment
- nerves for sensation
- lymphatic vessels for lymph drainage
4
Q
Dental pulp is … connective tissue made of …
A
- loose
- extracellular matrix
- diff cell types
- blood and lymphatic vessels
- nerves
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
6
Q
Is there hard tissue in dental pulp?
A
- none in normal pulp
- calcifications and pulp stones occur in aged teeth
7
Q
How different is pulp structure in primary and permanent teeth?
A
similar
- 4 zones in each
8
Q
4 histological zones in pulp
A
- odontoblast cell layer
- cell-free zone
- cell-rich zone
- pulp core
9
Q
Odontoblast cell layer contain what kind of cell?
A
- odontoblasts
10
Q
What’s within the cell-free zone?
A
- few cells
- mainly extracellular matrix
- nerve endings
11
Q
What’s within the cell rich zone?
A
many cells
- mainly fibroblasts
12
Q
What’s within the pulp core?
A
- central tissue
- nerves
- blood vessels
13
Q
From innermost of pulp to outermost, order the layers
A
- cell rich zone
- cell free zone
- odontoblast layer
- predentin
- mineralization layer
14
Q
Cells within pulp
A
- odontoblasts
- fibroblasts
- undifferentiated mesenchymal cells
- stem cells
- defence cells
15
Q
Coronal odontoblasts are … and have what features?
A
- columnar
- cellular process into dentinal tubule
- more cuboidal in root
16
Q
Odontoblasts produce what? and for how long?
A
- dentine (predentine)
- present throughout life of tooth
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
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
19
Q
3 types of junctions between odontoblasts
A
- tight
- desmosomes
- gap
20
Q
Role of tight junctions and desmosomes in odontoblasts
A
- maintains spacial relationships
- restricts substances in pulp from entering dentine
21
Q
Role of gap junctions in odontoblasts
A
- openings allow exchange of small molecules and cell-to-cell communications
22
Q
What is the most abundant cell type in dental pulp?
A
fibroblasts
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
Role of undifferentiated mesenchymal cells
- differentiate into odontoblast-like cells and fibroblasts
- number reduces with age
26
Role of dental pulp stem cells
- multipotent
- can differentiate into odontoblasts, chondrocytes, osteoblasts, adipocytes and neurons
27
Types and role of immune cells in dental pulp
- 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
What collagen is present in extracellular matrix of pulp?
- type 1 and 3
- forms a scaffold providing stability to pulp
29
What's in the ground substance/non-fibrous protein matrix of pulp?
- glycosaminoglycans, proteoglycans, glycoproteins and water
- hydrophilic molecules that swell when hydrated forming hydrogels that fill most of EC space
30
Role of ground substance in extracellular matrix of pulp
- 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
Explain vascular supply of pulp
- blood vessels originating in periodontal ligament enter pulp via apical foramen
- peripheral blood vessels branch out towards odontoblast layer and form small capillaries
32
Explain lymphatic drainage of pulp?
- drain tissue fluid
- thinner walls than blood vessels and have no red blood cells
33
Around ... nerve axons enter apical foramen
2500
34
Of the nerve axons coming through the apical foramen, 25% are ... and 75% are ...
- myelinated afferent nerve fibres
- unmyelinated C fibres
35
Explain myelinated afferent nerve fibres in teeth
- Schwann cells (form myelin sheath)
- transit pain sensation to CNS
- cell bodies in trigeminal ganglion
36
Explain unmyelinated C fibres in teeth
- 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
Explain the Plexus of Raschkow
- 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
Function of the dental pulp
- 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
Changes in pulp chamber with age
- young teeth have large pulp chamber
- old teeth have very narrow pulp chamber and root canals
40
How do the challenges for dentists change with young and old pulp chambers?
- 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
How is caries a spread of infection?
- from dental pulp into surrounding periodontal tissues
- causes periodontal abscess
42
How is periodontal disease spread?
- from surrounding periodontal tissues into dental pulp
- e.g through accessory root canals
43
Where are accessory root canals?
- can occur anywhere in the root
- mainly at root apex
44
What's an common cause of root canal treatment?
- failure to notice and clean accessory root canals
- causes persistant infection
45
Procedure of root canal
- infected tooth
- drill an opening
- fill and clear
- finish off
46
Collagen fibres are more towards ... so it's easier to do a pulpectomy from ...
- tooth apex
- apical region
47
Define 'diffuse calcifications or pulp stones'
- calcified masses can be formed in pulp
- as a response to chronic stimulus (caries infection etc) or age related change
48
How do pulp stones occur?
- 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
Afferent nerve endings terminate where?
- in dentine/near odontoblasts
50
Afferent nerve endings sense?
- pain
- mechanical
- chemical
- thermal
stimuli
51
3 theories for dentine sensitivity
- neural
- odontoblasts as receptors
- hydrodynamic
52
Explain neural dentine sensitivity
- dentine is directly innervated
- but not many nerve endings are detected in dentine
53
Explain odontoblasts as receptors dentine sensitivity
- odontoblasts act as receptors
- form synaptic contacts with nerve endings
54
Explain hydrodynamic theory
- fluid movement in dentinal tubules is sensed directly or indirectly by nerve endings
55
What is thought to increase sensory capacity?
branching of odontoblast processes at EDJ
