The development, physiology, histology of the dental pulp is briefly discussed. The features of the pulp as a connective tissue, its cells,fibers, innervation, vascularity are dealt with
5. DEFINITION
‘A richly vascularized and innervated
specialized connective tissue of
ectomesenchymal origin; contained in the
central space of a tooth, surrounded by the
dentin, with inductive,
formative, nutritive, sensory and protective
functions’
- Glossary of Endodontic terms
7. DEVELOPMENT
Downgrowths from dental lamina:
Enamel organ
Stages: Bud, Cap & Bell- deepening of
invagination
Tissue within the invagination:
‘ Dental Papilla’
8. DEVELOPMENT
8th week IUL: beginning
of papilla
Bell stage: inner layer of
papilla- odontoblasts
dentin
Dental pulp: Cephalic
neural crest cells
9. Blood supply
Oval/ Circular reticulated plexus in
alveolar bone (Saunders-1966 & Cutright-
1970)
Series of blood vessels- dental papilla:
future pulpal vessels
Vessels in dental sac basal wall: course to
papilla (Tobin 1972)
Pulpal artery: plexus of vessels at
pulpodentinal junction
10. Nerve supply
Early development: few axons enter
papilla- no peripheral nerve plexuses
Eruptive stage: rapid development -
plexus of Raschkow & terminals in
odontoblastic layer
Byers (1980)
11. Disorders: pulp
development
Vitamin D deficiency
Down’s syndrome: Jaspers -1981
Dens invaginatus
Pulpal dysplasia : Witkop- 1973
Regional odontodysplasia
Hypophosphatasia: Houpt et al (1970)
Beumer et al (1973)
Hereditary hypophosphatemia: Archard &
Witkop (1966)
Hypophysectomy
12. Pulp as a Connective Tissue
Cells, ground substance, fibers
Cells: a fundamental matrix
Site & precursor for the fiber complex
Collagen & reticulin
End product of the system
13. Cells of the Pulp
Fibroblasts
Odontoblasts
Defense & other cells
14. Fibroblasts
Basic cell type
Baume: mesenchymal cells, pulpoblasts,
or pulpocytes- progressive levels of
maturation
Active in collagen synthesis: fibers present
on the cell body & processes
15. Fibroblasts
Synthesize 6
Glycoproteins:
fibronectin
Fibronectin with Type
III collagen: Reticulin
fibers
faint
metachromasia, pho
sphatase & ATP
acitivity
Galdames et al,Int. J. Morphol. vol.29 no.1
Temuco mar. 2011
16. Fibroblasts
With age: more number & width of fibers
& cells reduce
More fibrous pulp: less defensive than
young cellular pulp
Responsible for increase in size of
denticles
17. Odontoblasts
Highly differentiated cell in pulp
Main function: dentin production
Uniformly stained hyperchromatic in tissue
sections
Cytoplasm: may or may not be evident
18. Morphologic variations:
A, Pulp horn (pear shaped)
B, coronal midpulp (spindle shape)
C, coronal midroot level (elongated club
shape)
D, mid-third of root (short club shape)
E, apical third of root (globules).
Marion D et al, 1991
19. Electron Microscope Findings
Large, closely aligned, multilayered sweet
potato shaped cells
3 to 4 µm wide & 8 to 10 µm long
Nucleus:
• Ellipsoidal – chromatin & nucleolus
• Double membrane covered
• Granules attached to outer membrane
20. Electron Microscope Findings
Nucleolus:
One to four in number ( Ivanyi 1972)
Ring shaped: fully developed- inactive
RNA synthesis
Compact: less developed- active RNA
synthesis
21. Electron Microscope Findings
Cytoplasm:
Extensive rER & numerous transitional vesicles
(Jesson-1968, Garant et al & Reith -
1968, Takuma & Nagai- 1971)
Vesicles: fine fibrillar material
Large Golgi apparatus : centre
Membrane bound granules: lysosomes
Secretory granules- abacus bodies: golgi
complex
22. Electron Microscope Findings
Mitochondria
evenly distributed
Centrioles present :
rudimentary cilium
Approx. 50 Ao
diameter filaments
200 to 250 Ao
diameter
microtubules
23. Electron Microscope Findings
Odontoblasts : 6-8 cells deep, palisade
formation along predentin border
Organelles: extend to terminal bar
apparatus level
Distal to this level: material constituting
odontoblastic process
24. Electron Microscope Findings
Odontoblastic process:
Dentinal fibers/ Tomes’ fibers
Traverses predentin, fills the lumen of
dentinal tubule
Coated vesicles: pinocytic & ingest
material from predentin
Numerous filaments: parallel to cell
membrane- characteristic
27. Electron Microscope Findings
Impermeable Junctions/ Tight Junctions:
Helps: maintain a distinct internal
environment
Plasma membranes appear to fuse &
offer a tight seal between cells
28. Electron Microscope Findings
Adhering Junctions:
Maintained by desmosomes: intercellular
bridges
3 types: Belt, Spot & Hemidesmosomes
Promote adhesion between cells
29. Electron Microscope Findings
Communicating Junctions/ Gap Junctions:
Mediate direct transfer of chemical
messages between cells
Exchange nutrients & signal molecules for
coordination of function
30. Gap junction & Tight
junction
Desmosome like junction
Sasaki T et al, 1982
31. Electron Microscope Findings
Odontoblastic Junctional Complexes:
Surface epithelial cells: terminal bars at
apical extremities
Consist of several components: junctional
complexes
Components: Zonula occludens, Zonula
adherens & Macula adherens
32. Electron Microscope Findings
Structures at border between odontoblastic
process & cell bodies: small gap junctions,
tight junctions & desmosome like junctions
Tight adhesion between odontoblasts: not
easily separated
33. Electron Microscope Findings
Nerve endings:
Presence of nerves in tubules:
controversial
Nerve endings in juxtaposition to
odontoblastic processes: reported
34. Electron Microscope Findings
Odontoblastic Communications:
Odontoblastic nuclei: inner border of
dentin
Odontoblastic processes : adjacent
processes through extensive lateral
branch system (Kaye & Herold, 1966)
Contact cells more centrally located: fine
protoplasmic processes-
fibronectin: cell to cell adhesion
35. Electron Microscope Findings
Odontoblasts: mesenchymal syncytium-
injury of one odontoblast affects others
Continuity of cells lost: injury following
operative procedures
Cytoplasm stains for:
RNA, lipids, ALP, ATPase,
ACP, non specific esterases, protein
carbohydrate complex : present
36. Electron Microscope Findings
Cell free Zone/ Layer of
Weil: under
odontoblasts in coronal
portion- nerve elements
Not observed in middle
& apical portions
(Gotjamanos,1969)
Cell rich Zone:
Fibroblasts &
undifferentiated
mesenchyme cells
37.
38. Defense cells
Histiocytes and Macrophages:
Pericytes : differentiate into fixed or
wandering
histiocytes under appropriate stimulation.
Highly phagocytic: remove
bacteria, foreign bodies, dead
cells, debris.
Pulpal macrophages & dendritic cells:
Langerhans’ cells
39. Defense cells
Polymorphonuclear Leukocytes:
Commonest : pulpal inflammation
Injury & cell death: rapidly migrate from
nearby vessels
Microabscess formation
Bacteria & dead cells.
Develop wider zones of
inflammation.
Silva et al, 2009
40. Defense cells
Lymphocytes and Plasma Cells:
Follows neutrophils.
Injury & resultant immune responses
Presence of a persistent irritant
42. Reserve Cells
Descendants of undifferentiated cells in
the primitive dental papilla
Multipotential cells : Fibroblast type
Capable: dedifferentiate/redifferentiate-
mature cell types.
Cell-rich zone: concentrations of such
cells.
43. Reserve Cells
Produce little collagen: not mature
fibroblasts (Frank- 1970)
Cytoplasmic connections: odontoblasts
& subjacent mesenchymal cells (Baume-
1980)
Near vessels: other mature cell types
Mast cells and odontoclasts:
inflammation.
44. Reserve Cells
Unique cells: calcified tissue - pulp cap/
pulpotomy[Ca(OH)2 ]
Along the calcified tissue: base of tubules
involved with
caries, restorations, attrition, abrasion
Not a true dentin; cells - not true
odontoblasts
45. Fibers of the Pulp
Reticular fibers: around blood vessels &
odontoblasts
Collagen- 640 Ao
Type III collagen: 28% to 45%- histologically
identified as reticulin
Type I also
46. Fibers of the Pulp
2 types of filaments
Rel. straight, approx 200 Ao diameter &
200 Ao periodicity
Coiled, branched & irregularly
beaded, 100 Ao diamter
47. Fibers of the Pulp
von Korff fibers:
Fine argyrophilic
fibers
Spirally twisted
bundles- cork
screw
Unmineralised
dentin/ predentin
Fibrillar framework
Bernick S
48. Fibers of the Pulp
Collagen deposition
Diffuse: no definite orientation
Bundle: large, coarse bundles run parallel to
nerves / independently (Stanley & Ranney,
1962)
Apical portion: more fibrous than coronal
(van Amerongen et al, 1983)
49. Fibers of the Pulp
Coronal pulp: more bundle collagen
Type III collagen & proteoglycans: arterial
plexus & odontoblasts
Extirpation of young cellular pulp: difficult
Aged pulp: like absorbent paper point
50. Ground substance
Structureless mass, gel-like in consistency: the
bulk of the pulp
Occupies the space between formed
elements
Influences:
Spread of infection
Metabolic changes
Stability of crystalloids
Effects of metabolic substances
51. Ground substance
Proteins with glycoproteins, acid
mucopolysaccharides
GAGs:
Hyaluronic acid (Engfeldt & Hjerpe, 1972)
Water retention
Ion Binding
Electrolyte distribution during mineralization
Collagen fibrillogenesis
52. Ground substance
‘Milieu interieur’: Engel (1958)
Metabolites & breakdown products-
exchange
Hyaluronic acid: metabolite transport
53. Ground substance
Pulp tissue hydroatatic pressure: 15 mm
Hg increase- early stages of inflammation
Depolymerization: microbial enzymes
change in ground substance
Hyaluronidases, chondroitin sulfatase
Mucopolysaccharidase activity: resorbing
deciduous teeth
54. Circulation of the Pulp
Systemic circulation
Microcirculation
Lymphatics
Control of blood flow
Transcapillary fluid exchange
Circulation in the inflamed pulp
Clinical correlations
55. Arterial blood supply to teeth
Right atrium
Right ventricle
Pulmonary artery
Lungs
Pulmonary vein
(left ventricle)
Aorta
CCA
ECA
Internal Maxillary artery
68. Regulation of pulpal blood
flow
Neuronal, paracrine & endocrine
mechanisms
Vasodilatation: neighboring tissues- drop
in pulpal blood flow & perfusion pressure
Pulp: vulnerable in gingivitis/ periodontitis
69. Neuronal regulation
Little/ no sympathetic vasoconstrictor tone
Neuronal vasodilator tone: sensory
neuropeptides
Cervical sympathetic trunk:
vasoconstriction
Neuropeptide Y & norepinephrine
70. Neuronal regulation
Blood flow sensory neuropeptides
Vasodilatation : CGRP release
Muscarinic receptors: ACh & VIP –
vasodilatation (Yu CY et al- 2002)
No parasympathetic vasodilatation: cat
pulp (Sassano et al- 1995)
71. Local control
Local tissue demands: regulate
hemodynamics
Endothelin-1 pulpal blood flow
Prostacyclin, NO : endothelium
Adenosine: ischemic & hypoxic tissue- low
pulpal oxygen tension
72. Humoral control
Angiotensin II : vasoconstrictive basal tone
Receptors: AT1, AT2- rat pulp (Souza PP et
al, 2007)
DOPA, epinephrine: vasoconstriction
ACh, Histamine, bradykinin : inhibit
vasoconstriction
73. Lymphatics
Drains filtered fluids & proteins: returns to
blood
Immune defense
Lymphatic markers: extensive lymphatic
system in pulp
Capillaries- pulp horns; leave via apical
foramen & lateral canals
74. From Berggreen E, Haug SR, Mkonyi LE,
Bletsa A: Characterization of the dental
lymphatic system and identification of cells
immunopositive to specific lymphatic
markers. Eur J Oral Sci 117(1):34–42, 2009
78. Wiig H, Rubin K, Reed RK: New and active
role of the interstitium in control of interstitial
fluid pressure: potential therapeutic
consequences. Acta Anaesthesiol Scand
47:111–121, 2003.
79. Circulation in the inflamed
pulp
Inflammation: vasodilatation & increased
vascular permeability- interstitial fluid
pressure
Reabsorption of tissue fluid: pressure-
disproves Pulpal strangulation theory
(Heyeraas & Berggreen- 1999, Heyeraas &
Kvinnsland- 1992)
80. Circulation in the inflamed
pulp
PGE2, Bradykinin, SP, Histamine: pulpal
blood flow
Serotonin: pulpal blood flow
Acute inflammation: 200% of control flow &
increased vascular permeability (Heyeraas &
Kvinnsland- 1992, Heyeraas et al- 1996)
LPS: circulatory dysfunction (Bletsa A et al,
2006)
81. Circulation in the inflamed
pulp
Endothelial perturbation: on exposure to
endotoxin/ cytokines
Reduced perfusion, VEGF down
regulation & microvessel density :
necrosis
Lymphangiogenesis : inflamed pulps
(Pimenta et al, 2003)
95. Innervation
Large no. of myelinated (A)&
unmyelinated (C) fibers
Premolar: 2000
Not all are nociceptors
Afferent: sensory
Efferent:
Sympathetic: circulation & eruption
96. Characteristics of sensory
fibers
Fiber Myelination
Location of
Terminals
Pain
Characteristics
Stimulation
Threshold
A-delta Yes
Principally in
region of pulp-
dentin junction
Sharp, pricking
Relatively
low
C No
Probably
distributed
throughout
pulp
Burning, aching,
less bearable
than A-delta fiber
sensations
Relatively
high,
usually
associated
with tissue
injury
97. Sensory fibers
Aδ: 1-5μ; 6-30 m/s
C: 0.4-1μ; 0.5-2 m/s
Pain localization:
Single neuron innervation
Low density propioceptors
Electrical stimulation: A fibers
110. Dentinal receptor theory
Intradentinal receptor: connections between
odontoblastic process & nerve fiber (Frank-
1969)
Transducer mechanism
AChE: demonstrated in several studies (Avery
and Rapp-1967); contrary too
Adrenergic : pulpal blood vessel walls
111. Hydrodynamic theory
Dentin pain & odontoblast displacement:
related
BrӓnstrӦm et al (1966, 1967, 1969, 1972)
and Lilja (1980): hydrodynamic
mechanism
131. References
Seltzer S, Bender J.B. Seltzer’s The Dental
Pulp. Biological considerations in dental
procedures. 3rd Edition
Hargreaves KM, Cohen S. Cohen’s
Pathways of the Pulp. 10th Edition
Ingle JI, Bakland LK. Ingle’s Endodontics.
5th Edition
132. References
Gronthos S, Mankani M, Brahim J, Gehron Roby
P, Shi S. Postnatal human dental pulp stem cells
(DPSCs) in vitro and in vivo. PNAS 2000; 97(25):
13625- 13630
In Vivo Generation of Dental Pulp-like Tissue by
Using Dental Pulp Stem Cells, a Collagen
Scaffold, and Dentin Matrix Protein 1 after
SubcutaneousTransplantation in Mice. Prescott
RS, Alsanea R, Fayad MI et al. J Endod
2008;34:421– 426
133. References
Cordeiro MM, Dong Z, Kaneko T et al.
Dental Pulp Tissue Engineering with Stem
Cells from Exfoliated Deciduous Teeth. J
Endod 2008;34:962–969
Wang Z, Pan J, Wright JT et al. Putative
Stem Cells in Human Dental Pulp with
Irreversible Pulpitis: An Exploratory Study. J
Endod 2010;36:820–825)
134. References
Hirata TM, Ishkitiev N, Yaeigaki K et al.
Expression of Multiple Stem Cell Markers in
Dental Pulp Cells Cultured in Serum-free
Media. J Endod 2010;36:1139–1144
Wang Y, Zhao Y, Jia W, Yang J, Ge L.
Preliminary Study on Dental Pulp Stem
Cell–mediated Pulp Regeneration in
Canine Immature Permanent Teeth. J
Endod 2013;39:195–201
135. References
Kim S, Lipowsky HH, Usami S, Chien S.
Arteriovenous Distribution of
Hemodynamic Parameters in the Rat
Dental Pulp. Microvasc Res 27, 28-38
(1984)