BYBYPROF.DR.ESSAM SOUSSAPROF.DR.ESSAM SOUSSA

BDS,MS,PHD.BDS,MS,PHD.

What is the What is the dental pulp dental pulp

tissuetissue??

WarningWarning::The Pulp Content Advisory Board The Pulp Content Advisory Board has rated this lecturehas rated this lecture::

Like the pulpLike the pulp

OutlineOutline Anatomy of the pulpAnatomy of the pulp Histology of the pulpHistology of the pulp

OdontoblastOdontoblast FibroblastFibroblast CellsCells Fibers and ground substanceFibers and ground substance VascularityVascularity nervesnerves

Pain and the pulp-dentin complexPain and the pulp-dentin complex Function of pulpFunction of pulp Age changesAge changes

PulpPulp

The dental pulp is The dental pulp is that loose delicate that loose delicate connective tissue connective tissue occupying the occupying the cavity lying in the cavity lying in the center of dentin.center of dentin.

From where it From where it comecome??

What are the origin?What are the origin?

Origin of the PulpOrigin of the Pulp

Condensed Ectomesenchyme.Condensed Ectomesenchyme. Dental Papil laDental Papil la

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Development: Development:

The dental pulp develops in the eighth week of I.U.L. in the anterior teeth, while in the posterior teeth it begins later.

At f irst the tooth pulp is known as the dental papil la, is known as pulp after dentin forms around it.

The dental papil la controls early tooth formation and morphology, so it causes the oral epithelium to invaginate and forms the enamel organ.

The young dental papilla is highly vascular and The young dental papilla is highly vascular and the cells of the dental papilla gradually develop the cells of the dental papilla gradually develop into into star shapedstar shaped, , roundedrounded or or spindle shaped spindle shaped fibroblastsfibroblasts. .

The Odontoblasts differentiate from the The Odontoblasts differentiate from the peripheral cells of the dental papilla. peripheral cells of the dental papilla.

Few large Few large myelinatedmyelinated nerves are found in the nerves are found in the pulp when the dentin of the crown is well pulp when the dentin of the crown is well advanced. advanced.

The The sympatheticsympathetic nerves follow the blood nerves follow the blood vessels into the pulp.vessels into the pulp.

Did you must know the Did you must know the shape of the pulp shape of the pulp

cavities?cavities?WhyWhy??

MorphologyMorphology

Each pulp organ is Each pulp organ is composed of a composed of a coronal pulpcoronal pulp located centrally located centrally in the crowns of in the crowns of teeth and the root teeth and the root or or radicular pulp.radicular pulp.

The coronal pulp:The coronal pulp: i t is present in the it is present in the pulp pulp

chamberchamber , in young , in young individuals it resembles the individuals it resembles the shape of the outer surface shape of the outer surface of the crown dentin and not of the crown dentin and not the outer surface of the outer surface of enamel. enamel.

I t has It has pulp horns pulp horns which are which are protrusions that extend into protrusions that extend into the cusp of each tooth. the cusp of each tooth.

Due to the continuous Due to the continuous deposit ion of dentin deposit ion of dentin throughout l i fe, the size of throughout l i fe, the size of the pulp chamber gradually the pulp chamber gradually decreasesdecreases and obliteration and obliteration of the pulp horns occurs.of the pulp horns occurs.

The radicular pulp:The radicular pulp:

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

In the anterior teeth the In the anterior teeth the radicular pulps radicular pulps are single are single and and in the posterior ones they are in the posterior ones they are multiplemultiple ..

The outline of the radicular The outline of the radicular pulp conforms with the dentino-pulp conforms with the dentino-cemental junction. cemental junction.

During root formation, During root formation, apical apical root end is wide root end is wide limited by limited by the epithelial diaphragm, it the epithelial diaphragm, it resembles a wide open tube. resembles a wide open tube.

With the complete formation of With the complete formation of the root, the root canal the root, the root canal becomes becomes tapering and tapering and narrowednarrowed . .

Further narrowing of the apical Further narrowing of the apical foramen may be produced by foramen may be produced by the deposit ion the deposit ion of cementum of cementum inside the foramen.inside the foramen.

The radicular portions of the The radicular portions of the pulp organs are continuous with pulp organs are continuous with the periapical connective tissue the periapical connective tissue through the apical foramen. through the apical foramen.

The average size of the apical The average size of the apical foramen of the foramen of the maxillarymaxillary teeth teeth in the adult is in the adult is 0.4 mm0.4 mm , while in , while in the the mandibularmandibular teeth it is teeth it is 0.3mm0.3mm in diameter.in diameter.

Apical foramen:Apical foramen:

Anatomy of the “Pulp SpaceAnatomy of the “Pulp Space””

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Accessory canals:Accessory canals:

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

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

Mechanism of formation of accessory Mechanism of formation of accessory canals is unknown but it is more l ikely to canals is unknown but it is more l ikely to

occur.occur.

1- 1- In areas, where the developing root In areas, where the developing root encounters a large encounters a large blood vesselblood vessel , where , where dentin wil l be formed around it, then dentin wil l be formed around it, then making the lateral canal or canals.making the lateral canal or canals.

2- Early degeneration of the epithelial 2- Early degeneration of the epithelial root root sheath of Hertwigsheath of Hertwig before the before the differentiation of the Odontoblasts wil l differentiation of the Odontoblasts wil l also lead to the formation of accessory also lead to the formation of accessory root canal.root canal.

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 is another possibility which will chamber is another possibility which will lead to the formation of accessory root lead to the formation of accessory root canal in the area of root furcation.canal in the area of root furcation.

Accessory canalsAccessory canals::

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Structures ,Structures ,is it important?is it important?

Histological structure Histological structure

The dental pulp is formed of The dental pulp is formed of specialize loose connective specialize loose connective t issue. t issue.

I t is formed of cells, f ibers, It is formed of cells, f ibers, intercellularintercellular substances, substances, blood vessels and nerves. blood vessels and nerves.

The intercellular substance is The intercellular substance is dense and gel l ike in dense and gel l ike in consistency and varies in consistency and varies in appearance from finely appearance from finely granular to f ibri lar. granular to f ibri lar.

I t is formed of It is formed of acidacid mucopolysaccharides & mucopolysaccharides & glycoproteinglycoprotein ’’ss ..

PulpPulp

The body of the pulp The body of the pulp constitutes of the constitutes of the connective t issue connective t issue which occupies the which occupies the space in the pulp space in the pulp chamber, although the chamber, although the matrix comprised matrix comprised mainly of mainly of type Itype I collagen relatively collagen relatively high high type IItype II in addit ion in addit ion to to proteoglycanproteoglycan ..

Although the Although the predominant cells type predominant cells type content is the content is the f ibroblastf ibroblast than the than the undifferentiated undifferentiated mesenchymemesenchyme . .

The macrophages may The macrophages may be present in inflamed be present in inflamed pulp, located sub-pulp, located sub-odontoblastic regionodontoblastic region

Which contains the Which contains the nervesnerves and and capil lariescapil laries these enter the pulp these enter the pulp through the apical foramen to through the apical foramen to supply the odontoblast layer as supply the odontoblast layer as well as the pulp itself.well as the pulp itself.

• Maintain t issue’s physical properties and integrity

• Control of growth and development and repairs

• Control of cell migration

• Control of diffusion of macromoleculesControl of diffusion of macromolecules

Functions Functions of of

pulpal extracellular matrixpulpal extracellular matrix

PredentinePredentine

The The predentinepredentine is the is the init ial matrix of the init ial matrix of the collagenous dentine collagenous dentine before it is mineralized.before it is mineralized.

There is always a layer of There is always a layer of the predentine between the predentine between the the Odontoblast layerOdontoblast layer and and the the mineralized dentinemineralized dentine ..

Homologous to the Homologous to the osteoid on the surface of osteoid on the surface of the forming bone.the forming bone.

Pulp

� Organization– Odontoblastic Zone– Cell-Free Zone

(Weil)– Cell-Rich Zone– Pulp Core

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Pulp Organization

� Odontoblastic Zone

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Pulp Organization

� Cell-Free Zone

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Pulp Organization

� Cell-Rich Zone

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Pulp Organization

� Pulp Core

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I-I- Cells of the PulpCells of the Pulp

The cells of the pulp may be divided into:The cells of the pulp may be divided into:I-Synthetic cells:I-Synthetic cells: (formative cells): (formative cells):

Odontoblasts and fibroblasts.Odontoblasts and fibroblasts.2-Defensive cells:2-Defensive cells: Histiocytes Histiocytes

(macrophages) small lymphocytes, (macrophages) small lymphocytes, eosinophils, mast cells and plasma cells.eosinophils, mast cells and plasma cells.

3-Progenitor cells:3-Progenitor cells: Undifferentiated Undifferentiated mesenchymal cells.mesenchymal cells.

1-1- Synthetic cells:Synthetic cells:

Odontoblasts:Odontoblasts:

The Odontoblasts are The Odontoblasts are found adjacent to the found adjacent to the predentin with the cells predentin with the cells bodies in the pulp and bodies in the pulp and cell processes in the cell processes in the dentinal tubules. dentinal tubules.

They are approximately They are approximately 5-7u in diameter and 5-7u in diameter and about 25 - 40u in about 25 - 40u in length. length.

The shape and The shape and arrangement of the arrangement of the cell bodies vary with cell bodies vary with the stage of tooth the stage of tooth development.development.

It consists of a single It consists of a single layer of cells in the layer of cells in the early stage of dentin early stage of dentin formation where the formation where the cells are regularly cells are regularly arranged and of arranged and of moderate length. moderate length.

In the later stages In the later stages of development, of development, the odontoblastic the odontoblastic layer is much layer is much broader, the cells broader, the cells are less columnar are less columnar and tend to be and tend to be pyriformpyriform where the where the broadest pan of broadest pan of the cell contains the cell contains the nucleus.the nucleus.

OdontoblastOdontoblast

Is the cells responsible for forming dentine and Is the cells responsible for forming dentine and the the Predentine Predentine , i t init ial ly secretes a collagenous , i t init ial ly secretes a collagenous matrix which then subsequently mineralized.matrix which then subsequently mineralized.

Also a great number of vesicles are seen along the periphery of the process.

While near the pulpal predentin junction the cell cytoplasm is devoid of organelles.

Immediately beneath the Immediately beneath the odontoblasticodontoblastic layer a layer a cell free zone can often be demonstrated, cel l free zone can often be demonstrated, Some believe that the Some believe that the cell free zonecell free zone is the is the area of mobil ization and replacement of area of mobil ization and replacement of Odontoblasts. Odontoblasts.

and this may explain why this zone is not clear and this may explain why this zone is not clear during early stages of rapid during early stages of rapid dentinogenesisdentinogenesis ..

Beneath the cell free zone, if present, there is a narrow zone of pulp tissue, this is a rich cell zone.

The Odontogenic zone is composed of the Odontoblasts, the cell free zone and the cell r ich zone.

The cell r ich zone is composed mainly of f ibroblasts and undifferentiated mesenchymal cells.

Cell free zone (of Weil)Cell free zone (of Weil)

• The cell free zone appears devoid of cells on its typical however, it can be seen that while it may not contain many cells nuclei it has numerous cell processes running through it sub-odontoblastic layer .

• also many small capillaries loops run through it as they odontoblastic capillary plexus

Cell r ich zoneCell r ich zone

The cell r ich zone The cell r ich zone unlike the name unlike the name suggests ,this zone suggests ,this zone appears to contains a appears to contains a high concentration of high concentration of the cell nucleithe cell nuclei

b-b- Fibroblasts:Fibroblasts: These are the most

numerous type of cells. They are spindle in

shape with elongated processes which are widely separated and l ink up with those of other pulpal f ibroblasts.

These processes give the cells a stellate appearance.

The nucleus stains The nucleus stains deep with basic dye deep with basic dye and the cytoplasm is and the cytoplasm is highly stained and highly stained and homogenous.homogenous.

These cells have a These cells have a dual functiondual function (for (for both synthesize and both synthesize and degradation of fibers) degradation of fibers) in the same cellin the same cell. .

Synthesis of collagen and its assembly into fibrils and fiber

2- Defensive cells:2- Defensive cells:

a- Histocyte or t issue a- Histocyte or t issue macrophage cell:macrophage cell:

In In l ight microscopelight microscope , the cells appear , the cells appear irregular in irregular in shapeshape with short blunt processes. with short blunt processes.

The The nucleus is smallnucleus is small , more rounded and darker , more rounded and darker in staining than that of f ibroblast. in staining than that of f ibroblast.

These cells are usually with These cells are usually with small bloodsmall blood vesselsvessels and and capil lariescapil laries . .

Their presence is disclosed by intra-vital dyes such trypan blue.

In case of inflammatioinflammation, it exhibits granules and vacuoles in their cytoplasm and their nuclei, increase in size and exhibit a prominent nucleolus.

Invaginations of plasma membrane are noted ultra-structurally with aggregation of vesicles or phagosomesphagosomes which contain phagocytozedphagocytozed dense irregular bodies.

b-b- Plasma cells:Plasma cells:

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

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

The arrangement of chromatin in the The arrangement of chromatin in the nucleus gives the cell a nucleus gives the cell a car wheelcar wheel appearance, both mature and appearance, both mature and immature cells may be found. immature cells may be found.

The mature type exhibits a typical small The mature type exhibits a typical small eccentric nucleus and more abundant eccentric nucleus and more abundant cytoplasm. cytoplasm.

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

c- Lymphocytes and Eosinophils:c- Lymphocytes and Eosinophils:

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

d- Mast cells:d- Mast cells:

May be present, they May be present, they have a round nucleus and have a round nucleus and their cytoplasm contains their cytoplasm contains many many granulesgranules..

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

Histamine is releasedHistamine is released Mast cells release histamine when an Mast cells release histamine when an

allergen is encountered. The histamine allergen is encountered. The histamine response can produce sneezing, response can produce sneezing, itching, hives and watery eyes. itching, hives and watery eyes.

3- Progenitor cells3- Progenitor cells

(The undifferentiated mesenchymal cells):(The undifferentiated mesenchymal cells):

They are smaller than They are smaller than the fibroblasts but the fibroblasts but have a similar have a similar appearance. appearance.

They are usually They are usually found found along the along the wallswalls of of blood blood vesselsvessels. .

These cells have the These cells have the potentiality potentiality of forming of forming other types of other types of formative or defensive formative or defensive connective tissue cells connective tissue cells

II- The fibers and ground II- The fibers and ground substances:substances:

The collagen f ibers The collagen f ibers in an extra cellular in an extra cellular ground substances ground substances surround the cells surround the cells of the pulp. of the pulp.

Both Both types I and II types I and II collagencollagen have been have been found in the pulp, found in the pulp, both types are both types are produced by produced by fibroblasts. f ibroblasts.

Fibroblast Fibroblast

In young pulp the In young pulp the fibers are f ibers are relatively sparse relatively sparse and delicate and delicate throughout the throughout the pulp and gradually pulp and gradually the bundles the bundles increase in size increase in size with advancing with advancing age, Where in age, Where in older pulp two older pulp two patterns of patterns of collagencollagen

I tI t ’’s distribution can be seen, one is a diffuse s distribution can be seen, one is a diffuse collagen network with no definite orientation.collagen network with no definite orientation.

The other is bundles of collagen, There are The other is bundles of collagen, There are no elastic f ibersno elastic f ibers in the pulp in the pulp except except those those present in the walls of the present in the walls of the larger bloodlarger blood vesselsvessels ..

The ground substances consist of acid The ground substances consist of acid mucopolysaccharidesmucopolysaccharides and neutral and neutral glycoproteinglycoprotein these substances are the these substances are the environment that promotes l i fe of the cells.environment that promotes l i fe of the cells.

I I I- Blood vessels and III- Blood vessels and nerves:nerves:

The pulp is The pulp is highly vascularizedhighly vascularized .. It is supplied by the It is supplied by the inferior and superior inferior and superior

alveolar arteriesalveolar arteries and drained by the same and drained by the same veinsveins in both mandibular and maxil lary in both mandibular and maxil lary regions. regions.

The branches of alveolar arteries which The branches of alveolar arteries which enter the tooth and its supporting t issues enter the tooth and its supporting t issues are different in its structures.are different in its structures.

Vasculature of the Pulp Apical Foramen Area

Arteriolar Size (≈ 150µm) Afferent & Efferent Vessels

Arterioles, Venules, Lymphatics Radicular Pulp

Central Location, Larger Lumen Coronal Pulp

Extensive Vascular Capillary Network

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Pulp vasculature

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

Small arteries which enter the apical canal run in a direct route to the coronal pulp.

Along their course they give off numerous branches in the radicular pulp that pass peripherally to form a plexus in the odontogenic region.

The pulpal blood flow is more rapid than in most areas of the body.

Veins and veinulesVeins and veinules

Are larger than the arteries also appear in the central region of the root pulp.

Veins measure 100-150u in diameter and their wall appear less regular and thin.

The endothelial cells, l ining these vessels appear more flattened and do not project into the lumen.

Lymph vesselsLymph vessels:: Blind-EndedBlind-Ended Thin WalledThin Walled DiscontinuitiesDiscontinuities

No Basal LaminaNo Basal Lamina Tissue Fluid Pressure Tissue Fluid Pressure

The draining of the anterior teeth pass to the submental lymph nodes, those of the posterior teeth pass to the submandibular and deep cervical lymph nodes.

Nerves:Nerves:

The pulp has an abundant nerve supply which The pulp has an abundant nerve supply which follows the distr ibution of the blood vessels. follows the distr ibution of the blood vessels.

Two types of nerve f ibers are presentTwo types of nerve f ibers are present ::

1-The non-myelinated 1-The non-myelinated nerves fibers:nerves fibers:

which are found in, close association with the blood vessels of the pulp and are sympathetic in nature where they control the contraction of the smooth muscles present in their lumen.

2-2- Myelinated nerves fibers: Myelinated nerves fibers: Which are sensory

parasympathetic nerves and they carry sensation to the sensory cortex of the brain.

The nerve f ibers enter the apical foramen and divide into many branches t i l l reaching peripherally the cell r ich zone, where they lose their myelin sheath.

The peripheral axons form a network of nerves located adjacent to the cell-rich zone.

This is termed the “parietal layer of nerves” or plexus of Raschkow.

Approx. 1800 non myelinated +400 myelinated

Intradentinal nerves are mostly found in pulpal horns.

These nerve fibers either terminate among or pass between the Odontoblasts where they then terminate adjacent to the odontoblastic processes at the pulp predentin border or in the dentinal tubules.

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

Theories of pain transmission: Theories of pain transmission:

(1) Direct neural (1) Direct neural theory.theory.

(2) Fluid or (2) Fluid or hydrodynamic hydrodynamic theory.theory.

(3) Odontoblasts (3) Odontoblasts transduction transduction theory. theory.

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Pulp venules

STIMULATION

Increased pulp interst it ial f luid

Increased pulp pressure

Increased tubular f luid flow

Release of inflammatory

agents?

Increased blood viscosity and rbc

congestion in capillary bed

Increased A-V shunt blood f low

Outward dentinal f luid flow and aspirat ion of odontoblasts

CNS, Pain, Reflexes

Vasodilation, Increased permeability

Pulpal axonal reflex due to dentine stimulation

Without infection, Vascular changes couldbe resolved.

Without infection, Vascular changes couldbe resolved.

Axon reflex

SP, CGRP

Dentine

Function:Function:

1- Inductive:1- Inductive:Pulp anlage (dental papil la)

induces the enamel organ formation and also determines the morphology of the tooth formed whether an anterior or a posterior tooth.

2- Formative:2- Formative: Pulp organ produces dentin. The pulpal Odontoblasts develop

the organic matrix and function in its calcif ication.

3-3- Nutrit ive:Nutrit ive:The pulp nourishes the dentin. The

nutritional elements are contained in the tissue fluid. Nutrition is mediated to the dentin through the Odontoblasts and their processes.

4-4- Protective:Protective:The sensory nerves in the tooth respond

with pain to all stimuli such as heat, cold, pressure, chemical agents and operative cutting procedures. Pain sensation is a useful alarm system of the pulp.

5- Defensive or reparative:5- Defensive or reparative:The pulp that responds to irritation by The pulp that responds to irritation by

producing reparative dentin and producing reparative dentin and mineralizing any affected dentinal tubules. mineralizing any affected dentinal tubules.

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

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

Age changes in the pulpAge changes in the pulp

1-With advancing age, there is continuous 1-With advancing age, there is continuous formation of dentin structure with the result formation of dentin structure with the result that the that the size of the pulp chambersize of the pulp chamber as well as well as the root canals is as the root canals is reducedreduced. .

The The apical foramenapical foramen is wide open in the is wide open in the young tooth but becomes young tooth but becomes narrowednarrowed with with age and is further constricted by age and is further constricted by cementum formationcementum formation

2-In embryonic pulp the 2-In embryonic pulp the cellular elementscellular elements are predominant, while with advancing are predominant, while with advancing age the pulp, becomes age the pulp, becomes poorerpoorer in cells and in cells and shows an increase in collagenous fibrillar shows an increase in collagenous fibrillar masses which are arranged in bundles, masses which are arranged in bundles, fewer undifferentiated cells available are fewer undifferentiated cells available are for emergencies, so the defense and for emergencies, so the defense and repair processes are slower in getting repair processes are slower in getting started.started.

3-In old pulp the 3-In old pulp the blood vessels and nerveblood vessels and nerve bundles are also bundles are also decreaseddecreased..

4-Reticular atrophy: 4-Reticular atrophy: In these changes the In these changes the OdontoblastsOdontoblasts are are

affected and affected and tend to degeneratetend to degenerate, in some , in some areas of the pulp they may have areas of the pulp they may have completely disappeared, vacuoles may completely disappeared, vacuoles may result. result.

The total effect is the production of a The total effect is the production of a lessened vitality of the pulp tissue and a lessened vitality of the pulp tissue and a lessened response to stimulation (reticular lessened response to stimulation (reticular atrophy).atrophy).

5-Pulp calcif ication :5-Pulp calcif ication : A further change associated with aging is the A further change associated with aging is the

appearance of appearance of deposits of calciumdeposits of calcium in the pulp. in the pulp. These deposits may be in the form of localized These deposits may be in the form of localized

masses known as pulp masses known as pulp stones stones oror denticles denticles , , sometimes large enough to be seen in an x-ray, or sometimes large enough to be seen in an x-ray, or alternatively as dif fuse calcif ications throughout alternatively as dif fuse calcif ications throughout the whole pulp. the whole pulp.

Pulp stonesPulp stones

Stones or denticlesStones or denticles

Denticles as well as diffuse calcif ication Denticles as well as diffuse calcif ication maybe found also in young and normal maybe found also in young and normal pulp and they tend to increase both in pulp and they tend to increase both in size and number with advance of age, size and number with advance of age, pulp stones are classif ied, according to pulp stones are classif ied, according to their structure as their structure as true and false denticles.true and false denticles.

Decalcif ied section of a tooth Decalcif ied section of a tooth (Hx.E) showing(Hx.E) showing

1.1. DentinDentin2.2. Attached pulp Attached pulp

stonestone3.3. PulpPulp4.4. free pulp free pulp

stonestone

1.1. DevelopmentDevelopment Epithelio-Mesenchymal InteractionsEpithelio-Mesenchymal Interactions . . Small groups of epithelial cells become Small groups of epithelial cells become

isolated from the epithelial root sheath isolated from the epithelial root sheath during development and end up in the during development and end up in the dental papilla. Here they interact with dental papilla. Here they interact with mesenchymal cells resulting in their mesenchymal cells resulting in their differentiation into odontoblasts. They form differentiation into odontoblasts. They form small dentinal structures within the pulp.small dentinal structures within the pulp.

Calcif ic DegenerationsCalcif ic Degenerations . . Spontaneous calcification of pulp Spontaneous calcification of pulp

components (collagen fibers, ground components (collagen fibers, ground substance, cell debris, etc.) may expand substance, cell debris, etc.) may expand or induce pulpal cells into osteoblasts. or induce pulpal cells into osteoblasts. These cells then produce concentric These cells then produce concentric layers of calcifying matrix on the surface of layers of calcifying matrix on the surface of the mass - but no cells become entrapped.the mass - but no cells become entrapped.

Diffuse Calcif icationDiffuse Calcif ication .. A variation of the above whereby seriously A variation of the above whereby seriously

degenerated pulp undergoes calcification degenerated pulp undergoes calcification in a number of locations. These bodies in a number of locations. These bodies resemble calcific degenerations except for resemble calcific degenerations except for their smaller size and increased number.their smaller size and increased number.

22..HistologyHistology

Calcified bodies in the pulp may be Calcified bodies in the pulp may be composed of composed of dentin, irregularly dentin, irregularly calcif ied tissuecalcif ied tissue , or , or bothboth . . A calcified A calcified body containing tubular dentin is referred body containing tubular dentin is referred to as a to as a "true" pulp stone or denticle."true" pulp stone or denticle.

True pulp stones exhibit radiating True pulp stones exhibit radiating striations reminiscent of dentinal tubules. striations reminiscent of dentinal tubules. Usually those bodies formed by an Usually those bodies formed by an epithelio- mesenchymal interaction, are epithelio- mesenchymal interaction, are true pulp stones. true pulp stones.

Irregularly calcified tissue generally does Irregularly calcified tissue generally does not bear much resemblance to any known not bear much resemblance to any known tissue and as such is referred to as a tissue and as such is referred to as a "false" pulp stone"false" pulp stone or or denticledenticle ..

False pulp stones generally exhibit either False pulp stones generally exhibit either a hyaline-like homogeneous morphology a hyaline-like homogeneous morphology or appear to be composed of concentric or appear to be composed of concentric lamellae. lamellae.

True denticlesTrue denticles consist of consist of irregular dentin containing irregular dentin containing traces of dentinal tubules traces of dentinal tubules and few odontoblasts. and few odontoblasts.

The development of this The development of this true denticle is not true denticle is not completely understood. completely understood.

I t has been postulated that It has been postulated that during root formation during root formation developmental developmental disturbances causing disturbances causing remnants of the epithelial remnants of the epithelial root of Hertwig to invade root of Hertwig to invade the pulp t issues causing the pulp t issues causing undifferentiated undifferentiated mesenchymal cellsmesenchymal cells

Both types of stonesBoth types of stones : : AA and and BB are false pulp stones, are false pulp stones, CC

is a true pulp stone. is a true pulp stone. AA is an "attached" stone (which is an "attached" stone (which

may become embedded as may become embedded as secondary dentin deposition secondary dentin deposition continues. continues.

BB and and CC are "free" stones found are "free" stones found within the pulp cavity. within the pulp cavity.

True Pulp StoneTrue Pulp Stone

LegendLegend AA - true pulp - true pulp stone stone

BB - dentinal tubules - dentinal tubules

If the pulp to form this If the pulp to form this irregular type of irregular type of dentin. dentin.

Tine denticles are Tine denticles are rare to occur, they are rare to occur, they are small in size and small in size and commonly found in the commonly found in the root canal near the root canal near the apical foramen.apical foramen.

The false denticlesThe false denticles are evidence of are evidence of dystrophic calcif ication of the pulp dystrophic calcif ication of the pulp t issue .t issue .

They contain They contain no dentinal tubulesno dentinal tubules . . They are formed of degenerated They are formed of degenerated

cells or areas of hemorrhage cells or areas of hemorrhage which act as a central which act as a central nidusnidus favoring the deposition of favoring the deposition of concentric layers in typical concentric layers in typical calcospherite form and continue to calcospherite form and continue to increase in size and in certain increase in size and in certain cases they f i l l up the pulp chamber cases they f i l l up the pulp chamber completely. completely.

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

False Pulp StoneFalse Pulp Stone

LegendLegend AA - pulp - pulpBB - dentin - dentin

CC - false pulp stone - false pulp stone

Fig. IVA-3: Section through a human tooth pulp which Fig. IVA-3: Section through a human tooth pulp which contains a number of calcif ied bodies (pulp stones).contains a number of calcif ied bodies (pulp stones).

Dentin and odontoblasts are visible at the right.Dentin and odontoblasts are visible at the right.

Pulp stones are classif ied Pulp stones are classif ied according to their location in according to their location in relation to the wall of the pulp relation to the wall of the pulp cavity. cavity.

All denticles are classif ied as All denticles are classif ied as being free, attached and being free, attached and interstit ial or embedded, free interstit ial or embedded, free denficles are so called when they denficles are so called when they are completely surrounded with are completely surrounded with normal pulp t issue, interst it ial normal pulp t issue, interst it ial denticles are embedded within denticles are embedded within the dentin and have developed by the dentin and have developed by the continued formation of dentin the continued formation of dentin around an attached denticle.around an attached denticle. false pulp stone

ConclusionConclusion

If pulp stones come close enough to If pulp stones come close enough to a nerve bundle causing pressure, a nerve bundle causing pressure, pain may be elicited. pain may be elicited.

This idea is not universally This idea is not universally accepted, because teeth are seen accepted, because teeth are seen in which the pulp is laden with pulp in which the pulp is laden with pulp stones without producing any pain. stones without producing any pain.

The close proximity of pulp stones The close proximity of pulp stones to blood vessels may cause atrophy to blood vessels may cause atrophy of it, i f the growing pulp stones of it, i f the growing pulp stones exert pressure upon the vessels.exert pressure upon the vessels.

Diffuse pulp calcif ication Diffuse pulp calcif ication commonly occurs on top of commonly occurs on top of hyaline degeneration in the hyaline degeneration in the root canal and not common root canal and not common in the pulp chamber.in the pulp chamber.

They are amorphous and They are amorphous and have no specif ic structure. have no specif ic structure.

They are irregular calcif ic They are irregular calcif ic deposit ion in the pulp t issue deposit ion in the pulp t issue fol lowing the course of blood fol lowing the course of blood vessels or collagenous vessels or collagenous bundle. bundle.

Also advancing age favors Also advancing age favors their development.their development.

Oral Biology & Oral Biology & Dental Dental

Morphology Morphology Mansoura Mansoura UniversityUniversity

Learning ObjectivesLearning Objectives1.1. How much inorganic material does normal dental pulp contain? What How much inorganic material does normal dental pulp contain? What

three features common to CT compose the pulp? Which type of three features common to CT compose the pulp? Which type of collagen fibers are found here? collagen fibers are found here?

2.2. Be able to label a diagram of the architecture of the pulp. Where is the Be able to label a diagram of the architecture of the pulp. Where is the cell-free zone located? What composes the odontogenic layer? In cell-free zone located? What composes the odontogenic layer? In which layer is the neural plexus located? Where is the cell-rich zone? which layer is the neural plexus located? Where is the cell-rich zone? What types of cells predominate in this layer? What types of cells predominate in this layer?

3.3. The dense capillary network under the odontoblasts reflect what The dense capillary network under the odontoblasts reflect what feature of this layer? Is there a lymphatic drainage of the pulp? Where feature of this layer? Is there a lymphatic drainage of the pulp? Where does tissue fluid drain in lieu of them? does tissue fluid drain in lieu of them?

4.4. List the two types of nerve fibers found in the pulp and the specific List the two types of nerve fibers found in the pulp and the specific function of each. With regard to the sensory fibers. Where to the function of each. With regard to the sensory fibers. Where to the myelinated fibers terminate? What type of pain is referred by myelinated fibers terminate? What type of pain is referred by myelinated fibers? from unmyelinated fibers? myelinated fibers? from unmyelinated fibers?

5.5. What are the two types of pulp? Do they differ in composition? Where What are the two types of pulp? Do they differ in composition? Where would a pulp horn be found? would a pulp horn be found?

6.6. What age-related changes occur in the pulp? Why? What age-related changes occur in the pulp? Why? 7.7. What are pulp stones? How are they thought to develop? What are the What are pulp stones? How are they thought to develop? What are the

two types of pulp stones and how can you distinguish one from the two types of pulp stones and how can you distinguish one from the other? other?