The dental pulp is that loose The dental pulp is that loose delicate connective tissue delicate connective tissue occupying the cavity lying occupying the cavity lying

in the center of dentin.in the center of dentin.

*The coronal pulp*The coronal pulp: it is present : it is present in the pulp chamber. in the pulp chamber.

*The radicular pulp*The radicular pulp:: it is that it is that part of the pulp extending part of the pulp extending from the cervical region of the from the cervical region of the crown to the root apex. crown to the root apex.

MorphologMorphologyyMorphologMorphologyy

Accessory canals:Accessory canals:

They are commonly seen to They are commonly seen to extend from radicular pulp extend from radicular pulp laterally through the root laterally through the root dentin to the periodontal dentin to the periodontal ligament. ligament.

They are They are numerousnumerous in the in the apical third of the root.apical third of the root.

Accessory Accessory canalscanals

1- it occurs in areas, where the developing 1- it occurs in areas, where the developing root encounters a root encounters a large blood vessellarge blood vessel, , where dentin will be formed around it.where dentin will be formed around it.

2- 2- Early degenerationEarly degeneration of the epithelial root of the epithelial root sheath of Hertwig before the differentiation sheath of Hertwig before the differentiation of the odontoblasts.of the odontoblasts.

3-Lack of complete union of the 3-Lack of complete union of the epithelial epithelial

diaphragmdiaphragm at the floor of the pulp at the floor of the pulp chamber.chamber.

Mechanism of formation Mechanism of formation accessory canalsaccessory canals Mechanism of formation Mechanism of formation accessory canalsaccessory canals

*Apical foramen*Apical foramen:: The pulp organs are The pulp organs are continuous with the periapical tissue through continuous with the periapical tissue through the apical foramen. the apical foramen.

The average sizeThe average size of the apical foramen: of the apical foramen:maxillary teeth : maxillary teeth : 0.4 mm0.4 mmmandibular teeth : mandibular teeth : 0.3mm0.3mm

Pulp ExposurePulp Exposure

Infected pulp

Abcess

Dental pain occurs in 12% of population.population.Dental pain occurs in 12% of population.population.

Dental pain is the most unkilling acute Dental pain is the most unkilling acute painpain

affecting human being.affecting human being.

The origin of the dental pain is difficult to localize.

(referred pain)

Dental pain Dental pain (acute (acute pulpitis)pulpitis)Dental pain Dental pain (acute (acute pulpitis)pulpitis)

Loss of the pulp Loss of the pulp results in loss of the results in loss of the pulp functions, but pulp functions, but

the tooth is still the tooth is still functioningfunctioning

The dental pulp is formed of The dental pulp is formed of specializedspecialized loose connective tissue: loose connective tissue:

Histological structure of Histological structure of the pulpthe pulp

cells fiberfiberss

intercellular intercellular substancessubstances

blood vessels and blood vessels and nervesnerves

peripheral zone peripheral zone

(odontogenic zone).(odontogenic zone).Central Central zone (pulp zone (pulp core).core).

Zones of the Zones of the pulppulp

Dentin

Odontogenic zone:Odontogenic zone:a- odontoblasts: a- odontoblasts:

Location: ALocation: Adjacent to the predentin djacent to the predentin with the cell bodies in the pulp and with the cell bodies in the pulp and cell processes in the dentinal cell processes in the dentinal tubules. tubules.

Dentin

B- Cell free zone B- Cell free zone ((the zone of the zone of WeilWeil)): : **It is present beneath the odontoblastic It is present beneath the odontoblastic layer.layer.**It is suggested to be the area of It is suggested to be the area of mobilization and replacement of mobilization and replacement of odontoblasts. odontoblasts.

C- cell rich zone:C- cell rich zone:It is present beneath It is present beneath the cell free zone.the cell free zone.It is composed of It is composed of fibroblasts and fibroblasts and undifferentiated undifferentiated mesenchymal cells.mesenchymal cells.

odontogeniodontogenic c zonezone

Cell free zone & Cell free zone & cell rich zone cell rich zone

might be might be artifactsartifacts..

Cells of the pulpCells of the pulp

2- Synthetic cells (formative 2- Synthetic cells (formative cells):cells):Odontoblasts and fibroblasts.Odontoblasts and fibroblasts.

Macrophages, lymphocytes, Macrophages, lymphocytes, eosinophils, mast cells and plasma eosinophils, mast cells and plasma cells. cells.

3- Defensive cells:3- Defensive cells:

1- Progenitor cells:1- Progenitor cells:

Undifferentiated mesenchymal Undifferentiated mesenchymal cells.cells.

1- Progenitor cells:1- Progenitor cells: (UMC):(UMC):

They are They are smallersmaller than than fibroblasts but have a fibroblasts but have a similar appearance. similar appearance.

They are usually found They are usually found alongalong the walls of blood vessels. the walls of blood vessels.

These cells have the These cells have the potentialitypotentiality of forming other of forming other types of formative or types of formative or defensive cells.defensive cells.

A- OdontoblastsA- OdontoblastsA- OdontoblastsA- OdontoblastsLength: Length: 25-40u25-40u Diameter: Diameter: 5-7u5-7u

In the early stagesIn the early stages of development of development odontoblasts consist of a odontoblasts consist of a single single layer of layer of columnarcolumnar cells . cells .

In the later stagesIn the later stages of development, of development, the odontoblasts appeared the odontoblasts appeared pyriformpyriform where the broadest part where the broadest part of the cell contains the nucleusof the cell contains the nucleus

2-Formative cells:

Odontoblasts areOdontoblasts are

longerlonger in the crown in the crown

cuboidalcuboidal rootwise,rootwise,

flatflat at the root at the root apexapex

The cell membranes of adjacent odontoblasts The cell membranes of adjacent odontoblasts exhibit junctional complexes.exhibit junctional complexes.

The clear terminal part of the cell body and The clear terminal part of the cell body and the adjacent intercellular junction is known the adjacent intercellular junction is known as as terminal bars.terminal bars.

Gap junction

desmosome

B- B- FibroblastsFibroblastsB- B- FibroblastsFibroblasts

*These are the most *These are the most numerousnumerous type of pulp cells. type of pulp cells.

*They are *They are spindlespindle in shape. in shape.

*They have *They have elongated processeselongated processes which are link up with those of which are link up with those of other pulpal fibroblasts (other pulpal fibroblasts (stellatestellate appearanceappearance). ).

*The *The nucleusnucleus stains deep stains deep with basic dye and the with basic dye and the cytoplasmcytoplasm is highly stained is highly stained and homogenous. and homogenous.

These cells have a double function: These cells have a double function: formation formation and and degradationdegradation of fibers and ground of fibers and ground substances. substances.

In young pulp, they are :In young pulp, they are :*Large cells .*Large cells .*With large multiple *With large multiple processes *Centrally processes *Centrally located oval nucleus, located oval nucleus, *Numerous mitochondria, *Numerous mitochondria, *Well developed Golgi *Well developed Golgi bodiesbodies *Well developed RER*Well developed RER

mitochondrmitochondriaia

FibroblastFibroblast

protein protein secreting secreting

cellcell

In periods of In periods of less activity and agingless activity and aging they appear smaller and round or spindle-they appear smaller and round or spindle-shaped with few organelles, they are shaped with few organelles, they are termed termed fibrocytesfibrocytes..

fibrocytefibrocyte fibroblasfibroblastt

Infected pulpInfected pulp

L

L

3- Defensive cells:3- Defensive cells:A- Histiocyte A- Histiocyte (macrophage):(macrophage): They appear irregular in They appear irregular in shapeshape with with

short blunt processes.short blunt processes.

The The nucleusnucleus is small, more rounded is small, more rounded & darker in staining than fibroblast.& darker in staining than fibroblast.

They are They are distributeddistributed around the around the odontoblasts and small blood odontoblasts and small blood vessels and capillaries. vessels and capillaries.

In case of inflammationIn case of inflammation::

*Nuclei increase in size and *Nuclei increase in size and exhibit a prominent exhibit a prominent nucleolus.nucleolus.

*It exhibits granules and *It exhibits granules and vacuoles in their cytoplasm. vacuoles in their cytoplasm.

UltastructurallyUltastructurally, ,

invaginations of plasma invaginations of plasma membrane with aggregation membrane with aggregation of vesicles or phagosomes .of vesicles or phagosomes .

*Macrophages are involved in the elimination of dead cells.

*Macrophages remove bacteria and interact with other inflammatory cells to protect the pulp during inflammation.

L

PhagocytosiPhagocytosiss

Hydrolytic enzymes

B-B- Plasma cells: Plasma cells:

These cells are seen during These cells are seen during inflammationinflammation. .

The nucleus of this cell is small The nucleus of this cell is small and appears and appears eccentriceccentric in the in the cytoplasm. cytoplasm.

The arrangement of chromatin The arrangement of chromatin in the nucleus gives the cell in the nucleus gives the cell a a cart wheelcart wheel appearance, appearance,

The plasma cells are known to The plasma cells are known to produce produce antibodiesantibodies..

C- C- LymphocytesLymphocytes

They are found in normal They are found in normal pulp and they increase pulp and they increase during inflammation.during inflammation.

D-EosinophilsD-Eosinophils

They are found in They are found in normal pulp and they normal pulp and they increase during increase during inflammation.inflammation.

E-E- Mast cells Mast cells::

*They have a round nucleus and *They have a round nucleus and their cytoplasm contains many their cytoplasm contains many granulesgranules. .

*They are demonstrated by using *They are demonstrated by using specific stains as specific stains as toluidine bluetoluidine blue..

*They produce *They produce histamine& histamine& heparin.heparin.

The ground substances of the The ground substances of the pulp:pulp:*The ground substances consists of acid *The ground substances consists of acid

mucopolysaccharides and neutral mucopolysaccharides and neutral glycoprotein.glycoprotein.

*These substances are the environment that *These substances are the environment that promotes life of the cells.promotes life of the cells.

**GlycoseaminoglycansGlycoseaminoglycans are bulky molecules are bulky molecules and hydrophilic, they form and hydrophilic, they form gelsgels that fill most that fill most of the extracellular space, They contribute to of the extracellular space, They contribute to the the high tissue fluid pressurehigh tissue fluid pressure of the pulp. of the pulp.

Blood vesselsBlood vesselsBlood vesselsBlood vessels*The pulp is highly vascularized. It is*The pulp is highly vascularized. It is

supplied by the supplied by the inferior and inferior and superior alveolar arteries. superior alveolar arteries.

*As the vessels enter the tooth, their *As the vessels enter the tooth, their walls become considerably walls become considerably thinner thinner than those surrounding the tooth. than those surrounding the tooth.

*Along their course they give *Along their course they give numerous branches in the radicular numerous branches in the radicular pulp that pass pulp that pass peripherallyperipherally to form to form a a plexusplexus in the odontogenic region. in the odontogenic region.

D

The rate of blood flow in the pulp of the tooth is The rate of blood flow in the pulp of the tooth is four timefour time the rate of blood flow in resting the rate of blood flow in resting muscle.muscle.

Laser Doppler Laser Doppler Flowmetry Flowmetry

It measures the rate of It measures the rate of pulpal blood flowpulpal blood flow

The capillaries adjacent to the odontoblasts The capillaries adjacent to the odontoblasts are are fenestratedfenestrated.. Such capillaries are Such capillaries are found in areas of rapid exchange.found in areas of rapid exchange.

Current Current pulp testspulp tests assess the function of assess the function of nervesnerves in the pulp, by the application of in the pulp, by the application of electric current or a rapid change in electric current or a rapid change in temperature.temperature.

Recently, , blood flow rateblood flow rate in the pulp is in the pulp is used to measure the degree of the pulp used to measure the degree of the pulp vitality.vitality.

Assessment of pulp vitalityAssessment of pulp vitality

Nerves of the Nerves of the pulppulpNerves of the Nerves of the pulppulpThe pulp has an abundant nerve The pulp has an abundant nerve

supply which follows the supply which follows the distribution of the blood vessels. distribution of the blood vessels.

Two types of nerve fibers are Two types of nerve fibers are present:present:

*Sympathetic in nature.*Sympathetic in nature.

They control the contraction of the They control the contraction of the smooth muscles of the blood smooth muscles of the blood vessels. vessels.

*Sensory nerves.*Sensory nerves.

Both contain myelinated and Both contain myelinated and unmyelinated axons.unmyelinated axons.

*More nerve endings are found in the *More nerve endings are found in the pulp hornspulp horns than in other peripheral areas of the coronal or than in other peripheral areas of the coronal or radicular pulp.radicular pulp.

*As the mylelinated nerves run coronally, they give off side branches and lose their myelin coat. They form then sub-odontoblastic plexus of nerves known as plexus of Rashkow. Few axons extend in-between the odontoblasts to give the nerve endings.

Sensory response in the pulp Sensory response in the pulp cannot cannot differentiatedifferentiate between heat, touch, between heat, touch, pressure or chemicals. This is because pressure or chemicals. This is because the pulp organs lack those types of the pulp organs lack those types of receptors.receptors.

Heat, Heat, Touch,Touch, Pressure, Pressure, ChemicalsChemicals

Pain

1- Inductive:1- Inductive:Dental papilla induces the enamel Dental papilla induces the enamel organ formation and also determines organ formation and also determines the morphology of the tooth.the morphology of the tooth.

Functions of the pulpFunctions of the pulpFunctions of the pulpFunctions of the pulp

2- Formative :2- Formative :Pulp organ produces dentin. Odontoblasts Pulp organ produces dentin. Odontoblasts develop the organic matrix and function develop the organic matrix and function in its calcification.in its calcification.

3- Nutritive :3- Nutritive :The pulp nourishes the dentin. The pulp nourishes the dentin. Nutrition is mediated through the Nutrition is mediated through the odontoblasts and their processes.odontoblasts and their processes.

Dentin

4- Protective:4- Protective:The sensory nerves in the tooth respond The sensory nerves in the tooth respond with pain to all stimuli, Pain sensation is a with pain to all stimuli, Pain sensation is a useful useful alarm systemalarm system of the pulp. of the pulp.

5- Defensive or reparative:5- Defensive or reparative:The pulp responds to irritation by producing The pulp responds to irritation by producing reparative reparative dentin and dentin and mineralizing mineralizing any any affected dentinal tubules. affected dentinal tubules.

These reparative reactions are an attempt These reparative reactions are an attempt to wall off the pulp from the source of to wall off the pulp from the source of irritation. irritation.

The presence of macrophages, lymphocytes The presence of macrophages, lymphocytes and leucocytes aid in the process of repair and leucocytes aid in the process of repair of the pulp.of the pulp.

Age changes in the Age changes in the pulppulpAge changes in the Age changes in the pulppulp

The size of the pulp The size of the pulp

The apical foramenThe apical foramen

The cellular elements The cellular elements

The bl. vessels & n.The bl. vessels & n.

VitalityVitality

Reticular atrophy:Reticular atrophy: The total affect is the The total affect is the production of a lessened vitality of the pulp production of a lessened vitality of the pulp tissue and a lessened response to tissue and a lessened response to stimulation.stimulation.

decreased

Pulp clacificationPulp clacification

localized localized ((pulp stonespulp stones ) diffusediffuse

False denticle False denticle True denticleTrue denticle

True denticlesTrue denticles

They consist of They consist of irregular irregular dentindentin containing traces of containing traces of dentinal tubules and few dentinal tubules and few odontoblasts. odontoblasts.

Remnants of the Remnants of the epithelial epithelial root sheathroot sheath invade the pulp invade the pulp tissues causing UMC of the tissues causing UMC of the pulp to form thispulp to form this irregular irregular type of dentin.type of dentin.

odontoblaodontoblastst

dentindentinal al tubulestubules

True denticles are True denticles are rarerare && smallsmall in size& in size& found near the found near the apical apical foramenforamen..

False denticlesFalse denticles*They are evidence of *They are evidence of dystrophicdystrophic

calcification of the pulp tissue .calcification of the pulp tissue .

*They contain *They contain nono denti dentinnal tubules and al tubules and can exist in any area of the pulp. can exist in any area of the pulp.

*They are formed of degenerated cells *They are formed of degenerated cells or areas of hemorrhage which act as or areas of hemorrhage which act as a central a central nidus nidus for calcification.for calcification.

*Overdoses of *Overdoses of vit. Dvit. D, may favor the , may favor the formation of numerous denticles.formation of numerous denticles.

*Pulp stones are *Pulp stones are classifiedclassified according to their location into: according to their location into: free, attached and embedded. free, attached and embedded.

*They continue to increase in *They continue to increase in sizesize and in certain cases they and in certain cases they fill up the pulp chamber fill up the pulp chamber completely.completely.

*If pulp stones come close *If pulp stones come close enough to a enough to a nervenerve bundle pain bundle pain may be elicited. may be elicited.

*The close proximity of pulp *The close proximity of pulp stones to stones to blood vesselsblood vessels may may cause atrophy of it.cause atrophy of it.

freefree

attachedattached

Diffuse pulp calcificationDiffuse pulp calcification

*Commonly occurs on top of *Commonly occurs on top of hyalinehyaline degenerationdegeneration in the in the root canal and not common in root canal and not common in the pulp chamber.the pulp chamber.

*They are *They are irregular calcific irregular calcific depositiondeposition in the pulp tissue in the pulp tissue following the course of blood following the course of blood vessels or collagenous bundle. vessels or collagenous bundle.

*Advancing *Advancing ageage favors their favors their development.development.