1. Dental pulp （牙髓） 何坤炎副教授：高醫醫學大學 口腔醫學院牙醫學系 07-3121101轉 7004 , 7029

2. 學習目標： 學習資源： pulp的解剖結構 pulp的的組織結構 pulp的功能 pulp的退行性變化
Ten Cate’s Oral histology. sixth edition, pp
Avery JK. Essentials of oral histology and embryology
A clinical approach. 1992, pp

3. Anatomy of the pulp * Human has 20 primary
It consists of soft connective tissue, vascular,
lymphatic, and nervous tissue
* Human has 20 primary
and 32 permanent in each
respective dentition
Total volume for permanent
teeth is about 0.38 ml
Avery JK. Essentials of oral histology and embryology
A clinical approach. 1992, p106, Fig.9.1

4. Pulp * Coronal portion--- pulp chamber occupies the crown of the tooth and resembles the shape the outer surface of crown dentin * Radicular portion--- root canal Apical foramen Accessory canal (Incidence: 33 % permanent teeth)
Avery JK. Essentials of oral histology and embryology
A clinical approach. 1992, p107, Fig.9.2

5. Coronal pulp --- pulp chamber
Coronal pulp --- pulp chamber * Pulp horn, pulp extend into cusp, No of these horns depends on cuspal number * With age, coronal pulp decreases in size owing to continued dentine formation, progresses faster on the floor than other wall
Avery JK. Essentials of oral histology and embryology
A clinical approach. 1992, p107, Fig.9.2

6. Radicular pulp * Continuous with the periapical
Root canal extend from cervical to
apex of the root, tapered and conical
* Continuous with the periapical
tissue through apical foramen
* Become smaller with age owing to
continued dentinogenesis, smaller
also due to apical cementum
deposition
Avery JK. Essentials of oral histology and embryology
A clinical approach. 1992, p107, Fig.9.3

7. Apical foramen is the pulp opening to periodontium
Opening varies in size from 0.3 to 0.6 mm, slightly
larger in maxillary than in mandibular teeth
2. Generally is centrically located in the newly formed root apex but become more eccentrically located with age, and functional influence

8. Apical foramen 3. Sometimes apical opening is found on the lateral
side of the apex
4.Tooth tipped apex deviate
in the opposite direction
Avery JK. Essentials of oral histology and embryology
A clinical approach. 1992, p108, Fig.9.4

9. Development
In earliest stage: the future papilla cause the oral epithelium to invaginate and form enamel organs
Dental papilla further control the forming enamel organs to be an incisor or molar
* Pulp is initially called dental papilla, after dentin
forms: pulp
* 8th week of embryonic life
Avery JK. Essentials of oral histology and embryology
A clinical approach. 1992, p110, Fig.9.7

10. Histology of the pulp
1. Large nerve trunk &blood vessel in the central
2. Peripherally:
odontogenic region
cell-free zone (Weil’s)
cell-rich zone
Avery JK. Essentials of oral histology and embryology
A clinical approach. 1992, p109, Fig.9.5

11. Histology of the pulp
Cell-free zone (Weil’s): area of mobilization and
replacement of odontoblasts
Cell-rich zone: composed principally of fibroblasts
and undifferentiated mesenchymal cells
* During early dentinogenesis,
many young collagen fibers
in this zone OD
CRZ
CFZ
From KMU

12. Odontoblast 5-7 m in diameter, 25-40 m in length
Near pulp-predentin junction,
cytoplasma is devoid of
organelles, at this clear zone
cell constricts to 3-4 m,
where the cell process enters
the predentinal tubule
Avery JK. Essentials of oral histology and embryology
A clinical approach. 1992, p109, Fig.9.5

13. Odontoblast process into mineralized dentin, contains
filaments and microtubes
through its length to DEJ
Recent information indicate
it extends through DEJ into
enamel as spindles
Avery JK. Essentials of oral histology and embryology
A clinical approach. 1992, p111, Fig.9.8

14. The form and arrangement of the cell
bodies of odontoblasts are not uniform
throughout the pulp
Highly columnar in crown,
Low cuboidal in middle of root,
Flat and spindle close to the apex

15. Ground substance (jell-like tissue)
Components of pulp
Ground substance (jell-like tissue)
1) Proteoglycans or
acid mucopolysaccharides (酸性黏多醣)
2) Glycoproteins (醣蛋白)
Alternation in composition caused by age or disease,
interfere with this function, producing metabolic
changes, reduced cellular function, and irregularities in
mineral deposition

16. Fibroblast: stain deeply with basic dyes, and
cytoplasm is lighter stained appears homogeneous,
typical stellate and extensive process
Function in collagen formation and protein synthesis
* Also ingesting and degrading collagen when
approximate stimulated
Avery JK. Essentials of oral histology and embryology
A clinical approach. 1992, p112, Fig.9.12

17. Fibroblasts
Characterized by their functional state, young pulp actively
producing matrix and collagen, star shape, have multiple
process with ovoid nucleus
Abundant RER and mitochondria
Old pulp--- fiber increase, smaller
and spindle-shaped with few
organelles
Avery JK. Essentials of oral histology and embryology
A clinical approach. 1992, p112, Fig.9.13

18. Collagen and fine fibers in pulp
Collagen bundles: cross-sections at 64 nm
intervals, range in length m or
more
Fine collagen fibrils: argyrophilic fibers,
originate from pulp fibroblasts  formation
of predentin

19. Both type I and III collagen approximate
(55:45) in the pulp remain constant from
beginning of tooth development to tooth
maturity
Type I probably produced by odontoblast,
type III by pulp fibroblasts

20. Young pulp fibers are relatively sparse
If pulp is irritated, fibers may accumulate rapidly,
older pulp contain more collagen of both
bundle and diffuse type
* The greatest concentration
of collagen seen in most
apical portion of the pulp
Avery JK. Essentials of oral histology and embryology
A clinical approach. 1992, p114, Fig.9.17

21. Histiocyte or macrophage
irregularly shaped with short blunt
process. Smaller, more rounded, and
darker staining than fibroblast, and
exhibits granular cytoplasm.
* Disclosed by trypan blue (intravital dyes), aggregation of vesicles, phagocytized dense irregular bodies

22. Vascularity Peripheral plexus
Vessels arising from external carotids to superior or
inferior alveolar arteries. Thin-walled arteries and
arterioles enter apical canal and pursue a direct
route up to coronal area
Central core
Peripheral plexus
Avery JK. Essentials of oral histology and embryology
A clinical approach. 1992, p115, Fig.9.18, 19

23. Vascularity subdivide to form an extensive vascular capillary
Arteriole in coronal portion of pulp they divide and
subdivide to form an extensive vascular capillary
network, U-looping is seen, this anatomical
configuration is thought to
be related to regulation of
blood flow
Avery JK. Essentials of oral histology and embryology
A clinical approach. 1992, p115, Fig.9.19

24. * Pulpal blood flow is most rapid than areas
of the body
Arterioles is mm/second
Venules is 0.15 mm/second
Capillaries about 0.08 mm/second
* Pulpal pressure is among the highest of
the body

25. Blood vessels
Tunica intima --- squamous or cuboid endothelial cells surrounded by closely associated basal lamina
Tunica media layers of smooth muscle cells, occasionally endothelial cell wall in contact with muscle
cells this is termed a “myoendothelial junction”
Tunica adventitia --- made up of a few collagen fibers forming a loose network around the large arteries

26. Veins and venules 1. 100-150 m in diameter, larger than arteries
2. Tunica adventitia lacking or appear as
fibroblast
3. Endothelial cells more flattened
4. In central region of root pulp

27. Capillary appears as “endothelium - lined”
tubules (8-10 m), nuclei may be lobulated
and cytoplasma projections into luminal
surface
* Fenestrated capillaries may involved in rapid transport of metabolites, for predentinal matrix formation, and calcification of dentin

28. Nerves 1. Most nerves are myelinated 2. Mediate the sensation of pain
caused by external stimuli
3. Non-myelinated nerves closed
to blood vessels, sympathetic
in nature, vasoconstriction
4. Parietal layer of nerve---
plexus of Raschkow
Avery JK. Essentials of oral histology and embryology
A clinical approach. 1992, p116, Fig.9.21

29. 5. Nerve ending close to odontoblast plasma membrane separated only by 200 Å cleft
6. Most of nerve endings in odontoblast are sensory afferents and sympathetic from superior cervical ganglion
Avery JK. Essentials of oral histology and embryology
A clinical approach. 1992, p117, Fig.9.23

30. Pulp tissue nerve fibers
1. A fibers fast conducting, diameter 1-6 m , for early stage of damage in dentin to sense the pain, for sharp, localized pain
2. Aβ fibers 1%, 6-12 m
3. C fibers--- nonmyelinated, m, dull and diffuse pain

31. Most of nerve fibers and endings are found
in pulp horns
Sensory response in pulp can distinguish among thermal, mechanical and tactile
*Raschkows nerve plexus and free nerve
ending of unmyelinated axons in predentin
and dentin layer

32. Functions of the pulp 1. Initiative (inductive) 2. Formative
3. Protective
4. Nutritive
5. Reparative

33. Functions of the pulp
1. Inductive---induce oral epithelium differentiate
into dental lamina and enamel organ formation,
and becoming a particular type of tooth
2. Formative---odontoblast develop organic matrix
and function in its calcification, dentin is formed

34. Functions of the pulp
3. Nutritive- nourishes dentin through odontoblast
and their process, and by blood vascular system
4. Protective---sensory nerves responds with pain
to all stimulus
Sympathetic---reflux, control circulation of
blood vessel

35. Functions of the pulp 5. Defensive or reparative---
producing reparative dentin
and mineralizing any
affected dentinal tubules
Macrophage and PMN aid
in the process of repair
Avery JK. Essentials of oral histology and embryology
A clinical approach. 1992, p119, Fig.9.26

36. Functions of the pulp Provide vitality to teeth with its cells, blood
vessels, and nerve
Endodontic treated tooth function without
pain but lost its protective mechanism that
the pulp nerve provide

37. Regressive Changes * Cell changes --- aging pulp are characterized
by fewer cells, decrease in size and number of
various cytoplasmic organelles, less
perinuclear cytoplasma, and possess long, thin
cytoplasmic processes

38. Regressive Changes * Fibrosis -- accumulation of diffuse fibrillar
components and bundles of collagen fiber Collagen increase is noted in medial and
adventitial layers of blood vessels Any external trauma usually cause localized
fibrosis and scarring effect

39. Regressive Changes * Vascular changes --- outer diameter of vessels
walls becomes greater as collagen fibers
increase in the medial and adventitial layers
* Calcification in the walls of blood vessels is
found in the region near apical foramen

40. Pulp stone <denticle> Classification:
Structure---true, false denticle
and diffuse calcification
More than 60 y/o of age
♣ Incidence and size of pulp stones increase with age
Avery JK. Essentials of oral histology and embryology
A clinical approach. 1992, p120, Fig.9.28

41. Pain conduction– three mechanisms
1. Dentin contains nerve ending
and directly innervated
2. Odontoblasts acts as a receptor
and are coupled to nerve in the
pulp
3. Receptors are in the pulp and are
stimulated by fluid movement
through the dentinal tube
Avery JK. Essentials of oral histology and embryology
A clinical approach. 1992, p118, Fig.9.25

42. Pain conduction--Hydrodynamic theory
Stimulation causes odontoblasts and their
processes to move contact with nerve endings
in the predentin and pulp.
* It results in mechanoreceptors receiving the
impulse that conduct pain response to central
nerve system
Avery JK. Essentials of oral histology and embryology
A clinical approach. 1992, p118, Fig.9.25

43. Clinical considerations 1
Clinical considerations 1. Nonvital tooth becomes brittle and is subject
to fractures 2. Aging pulp chamber become smaller, due to
excessive dentin formation  difficult to
locate root canal
3. Accessory canals--- deep periodontal pocket
may cause inflammation of dental pulp

44. 結論 ♣ The vitality of dentin-pulp complex plays an
important role in maintenance of a functional
dentition, and maintaining tooth vitality while
focusing particularly on the cell of pulp. ♣ Preservation of the vitality of pulp during
operative procedures is the most important
challenges to clinical dentist