Oral histology - Dental pulp by Dr. Zain Qayyam

1. Dental pulp

3. organisation
• Loose c.t
• Odontoblasts (periphery)
• Nerve terminals(trigiminal afferents)
(periphery )
• Specialized antigen presenting cells periphery)
• The rest of the cells act as a support system !

5. • Blood vessels and nerves >apical foramen
• Root>at least one canal !
• Vascular canals between roots (furcation) in
multirooted teeth

6. composotion
• Cells + (more)extracellular matrix(fibers in a semi-
fluid gel)
• So :
1)cells
2)fibers
3)non-fiberous matirx (gel)
• 75% water 25% organic .
• Compostition change during development and
vary between teeth types

7. Extracelluar matrix
• Extracellular matrix:
• Polysaccahrides ,proteins >>>forming a
stabilizing scaffold that is far from inert
>>>affecting cells :development ,migration
division ,shape and function .
• Collagen 25-32% dry weight

8. Fibers
• Collagen type 1
(bone,cementum,skin,dentine)
Irregular except at the periphery where They
become parallel to predentine .
(early in development >>right angles to
predentine “von kroff ”.

10. Collagen fibers
Collagen I
• α1, α 2 chains
• 56% (of pulpal collagen )
Collagen III
• α1
• 41%

11. Fibers
• Collagen IV
• Collagen V
• Microfibrils (fibrillins)
beaded large glycoproteins.

12. Non-fibrous matrix
• Glycosaminoglycans
• Proteoglycans
• Other adhesion molecules:
Fibronectin,laminin.

13. Glycosaminoglycans
GAG’s :polysacchrides chains composed of
repeating disacchrides linked covalently to proteins.
bulky,hyrophilic,fills most of the extracellular space,
swell when hydrated which :
>>contributes to the high fluid pressure
>> gives high support
>> facilitates easy movement of water
soluble materials and cells.

14. GAG’s
GAG’s Developing
tooth
Info: Functions Mature pulp
Chondrotin
sulphate
Major GAG 12%
Dermatan
sulphate
Small amounts 20%
hyalorunan Minor
component
Only GAG
found unbound
to prtns.
Mechanical
Cell migration
During
development .
60%
Heparan
sulphate

15. Proteoglycans
• Core protein of variable sizes surrounded by
GAG’s and other sugars .
• They are part of a larger group called
GLYCOPROTEINS :have GAG’s as part of their
side chains.

17. Other adhesion proteins
• Fibronectin :Glycoprtn .
attaching cells to extracelluar matrix
regulating cell shape ,migration ,differentiation
part of integrins (cell adhesion molecules )
• Laminin (integrin)
in basement membranes (binding epi to extracelluar
matrix ,binding some signaling molecules)
found around endothelial cells and schwan cells
Odontoblasts cell bodies and processes are coated with
laminin

18. Cells
• Odontoblasts
• Fibroblasts
• Defense cells
• Undifferentiated cells
• Blood vessels
• Nerve cells

19. Odontoblasts
• Dentine formation
• Post mitotic cells (cannot divide)
• If the insult was too high >>odontoblast
death>> Subodontoblastic cells divide to form
tertiary dentine.

21. ODONTOBLASTS
• Columnar cells(crown ),cuboidal(radicular).
• Single long cell process through tubule>
predintine and dentine .

22. Odontoblasts
cell junctions
• (provide integrity, render odontoblastic layer
permeable )
1.Desmosomes (mechanical union )
Intracellular >between fibrils
Intercellular>between cells
2.Adherens
Small molecules between cells
Play a role in synchronizing activity of odontoblasts .

23. Odontoblasts
cell junctions
1.dendritic antigen presenting cells .
Nature of the relationship is unknown but could be that
odontoblasts producing proinflammatory mediators .
2.Nerve cells
Chemical synapse .
Electrical synapse by gap junctions . (no high evidence )
3.odontoblast-odontoblast juntions
4.odontoblast-fibroblast junctions
Odontoblast-mesenchymal cells junctions .

25. Odontoblasts
• First cells to encounter dental pathogens
• Express IL-8 recruitment of neutrophils .

27. Fibroblasts
• adherens(junctions)
Fibroblast-fibroblast /fibroblast-odontoblast
Arms of stars
• Stellate (shape)

29. Fibroblasts..
• Play a role in the:
1. production of fibers and matrix
Their production is low ,turnover is low, so few
organells .
2.They produce a hard tissue after turnover
resemling bone more than dentine (stones?)
3.Growth factors and cytokines during development
4.Cell division
5.Apoptosis (programmed cell death )

30. Defence cells
1)T-lymphocytes
usually few in number but increase after injury to pulp.
2)Macrophages (histocytes in resting form)
Hard to be distinguished from fibroblasts
Mostly around endothelial cells and odontoblasts
3)Mast cells (absent in pulp)
4)Dendritic antigen presenting cells
3 main processes
Around endothelial cells and odontoblasts
Stimulate division of t-lymphocytes
May travel with trapped antigens to regional lymph nodes .

33. Note..
• Pulp’s response to injury has both
inflammatory and immune components.
Immune +neural system relationship

34. Blood vessels of pulp
• (architecture similar to nerves )
• Enter from :1)apical foramen
2) lateral canals
• Stay in in a bundle in the root ,branch profusely
when reaching pulp chamber .
• Arterioles and venules

35. • Vasoconstrictors from nerve endings to
endothelial smooth muscles to control pulpal
blood flow .
• Calcitonin (vasodilator)

36. • Subodontoblastic capillary plexus :
• Insultrelease of vasoactive molecules .
• With and underneath odontoblasts and
between odontoblasts and predentine .
• doesn’t enter tubules .

38. • Capillaries with class II molecule expressing
dendritic cells around them:
1.Antigen presenting
2.Phagocytes
pulpal blood flow is 6-20-ml/min per 100g of
tissue.
High pulsatile interstitial tissue pressure to wash
out toxins from outside .

39. Nerves of dental pulp
• Heavely innervated
• 2500 axons enter the apical foramin of a mature premolar .
• 25% are myleinated afferents of trigiminal gangelion
90% narrow Aδ fibers (1-6ɱm in diameter )
10%wider Aβ fibers
• Close association to blood vessels
• Branch profusely in coronal pulp chamber

40. • Plexus beneath odontoblasts “raschkaw plexus” is
evident after eruption of the tooth .
• Marginal plexus between odontoblastic layer and
predentine .
• Some nerves enter dentinal tubules with odontoblastic
processes
• Branching increases surface area for activation
• Schwan cell covering many axons so axon-axon
interaction is possible .

41. Nerve fiber types
1. Myleinated trigiminal afferents
Carry sharp pain centrally .
2.Aβ afferents
Non-noxious stimuli.
3.C-fibers :
non myleinated afferents carry noxious information centrally.
sympathetic afferents that supply arterioles smooth muscles and mediate their vasoconstrictive
effects by :
a)Noradernaline
b)Neuropeptides
VASODILATORS :
Parasympathetic (acetylcholine) low evidence of their presence in dental pulp .
Mostly axon reflexes and build up of metabolites locally cause vasodilation.
Nitric oxide is the principle molecule to induce vasodilation .(tissue hypoxia)

42. Nerve endings
• Autonomic nerves end in smooth muscles of
arterioles .
• Aδ afferents enter tubules of dentine and
predentine and detect stimuli outside dentine
(marginal plexus).
• some end in junctions with odontoblasts(low
evidence of this junction)

43. Nerve endings
• All nerves in area of predentine –pulp border
are NAKED :
• lost their 1) schwan cells 2) axolemmas .
So they are exposed to extracellular
environment . And any changes in extracellular
environment results in NEUROPEPTIIDE (Ex.
Calcitonin gene related peptide GCRP) release ..
which has a functional role in regulation rather
than sensation .

44. Molecules
• GCRP:
From cell bodies in trigeminal ganglion and moves
by axonal transport to the dental pulp.
Vasodilator
Control hard tissue production
• NGF+receptors
From fibroblasts mostly
Attract leucocyte after insult (chemo attractant).

45. Regions of dental pulp
Outiside
Inside
Predentine
Supraodontoblastic region
Odontoblastic layer
Subodontoblastic zone :
cell free zone
Cell rich zone
Bulk of the dental pulp

48. Regions
• Supraodontoblastic region :
Artifact
Second after odontoblast to receive stimuli .
Made of :
1)Unsheathed axons (crown )
Predentinal axons of “bradlaw”
their function is :
End within tubules to detect changes in extracellular matrix
and fluid movements in tubules .
(which otherwise would be delayed due to the barrier
properties of the odontoblastic layer )
2)Dendritic antigen presenting cells

49. • Cell free zone of “weil” :
Artifact.
Absent in radicular pulp.
• Cell rich zone :
Artifact ?
Cells of capillary and nerve plexus ,schwan
cells,endothelial cells ..
Bulk of pulp
Loose c.t

50. Age related chnges
• With age 
Pulp becomes more fibrous ,less vascular and
less innervated ,we start noticing stones

51. stones
Stones:
They are mineralized
Age related and not pathological
If one tooth presents with stones,other teeth
within sameperson might exhibit stones.

52. stones
Appearance :
Tiny spicules (snow storm)
Discrete pulp stones (single/groups)
Resemble dentine ,tubular ,(true denticles )
Resemble bone,cells embeded within them
(false denticles )

53. Role of pulp
• Produce dentine
Primary
Secondary
Tertiary

54. Thank you …..