Dental pulp （牙髓）何坤炎副教授：高醫醫學大學何坤炎副教授：高醫醫學大學 口腔醫學院牙醫學系口腔醫學院牙醫學系 07-312110107-3121101 轉 轉 7004 , 70297004 , 7029 kuyeho@kmu.edu.twkuyeho@kmu.edu.tw

學習目標：pulp的解剖結構pulp的的組織結構pulp的功能pulp的退行性變化

學習資源：學習資源：1.1. Ten Cate’s Oral histology. sixth edition, pp 397-416Ten Cate’s Oral histology. sixth edition, pp 397-4162. Avery JK. Essentials of oral histology and embryology A clinical approach. 1992, pp105-122

Anatomy of the pulpIt consists of soft connective tissue, vascular,lymphatic, and nervous tissue

* Human has 20 primary and 32 permanent in each respective dentitionTotal 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

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

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

Radicular pulp• 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

Apical foramen is the pulp opening to periodontium

1. 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 wit

h age, and functional influence

Apical foramen3. 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

DevelopmentIn earliest stage: the future papilla cause the ora

l 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

Histology of the pulp1. 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

Histology of the pulpCell-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

From KMU

OD

CFZ

CRZ

Odontoblast5-7 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

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

The form and arrangement of the cell

bodies of odontoblasts are not uniform

throughout the pulpHighly columnar in crown,

Low cuboidal in middle of root,

Flat and spindle close to the apex

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

Components of pulp

Fibroblast: stain deeply with basic dyes, and cytoplasm is lighter stained appears homogeneous, typical stellate and extensive processFunction 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

FibroblastsCharacterized 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

Collagen and fine fibers in pulp

Collagen bundles: cross-sections at 64 nm

intervals, range in length 10-100 m or

more

Fine collagen fibrils: argyrophilic fibers,

originate from pulp fibroblasts formation

of predentin

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

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

Histiocyte or macrophageirregularly 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

VascularityVessels arising from external carotids to superior orinferior alveolar arteries. Thin-walled arteries and arterioles enter apical canal and pursue a directroute 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

Vascularity

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

* Pulpal blood flow is most rapid than areas of the body Arterioles is 0.3 -1 mm/second Venules is 0.15 mm/second Capillaries about 0.08 mm/second

* Pulpal pressure is among the highest of the body

Blood vessels

Tunica intima --- squamous or cuboid endothelial cells surrounded by closely associated basal lamina

Tunica media --- 1-3 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

Veins and venules

1. 100-150 m in diameter, larger than arteries2. Tunica adventitia lacking or appear as fibroblast

3. Endothelial cells more flattened

4. In central region of root pulp

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

Nerves1. 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

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

Pulp tissue nerve fibers 1. A fibers fast conducting, diameter 1-6 m , f

or early stage of damage in dentin to sense th

e pain, for sharp, localized pain

2. Aβ fibers 1%, 6-12 m

3. C fibers--- nonmyelinated, 0.4-1.2 m, dull a

nd diffuse pain

Most of nerve fibers and endings are found in pulp hornsSensory 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

Functions of the pulp

1. Initiative (inductive)

2. Formative

3. Protective

4. Nutritive

5. Reparative

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

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

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

Functions of the pulp

Provide vitality to teeth with its cells, bloodvessels, and nerve Endodontic treated tooth function without pain but lost its protective mechanism thatthe pulp nerve provide

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

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

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

Pulp stone <denticle>

Classification:Structure---true, false denticle

and diffuse calcification

More than 60 y/o of age ♣ Incidence and size of pulp sto

nes increase with age

Avery JK. Essentials of oral histology and embryology A clinical approach. 1992, p120, Fig.9.28

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 pulp3. 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

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

Clinical considerations1. Nonvital tooth becomes brittle and is subject to fractures2. 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

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