Presented byPresented by,,

Dr. Rahul AgrawalDr. Rahul Agrawal

(P.G.) First Year(P.G.) First Year

Guided byGuided by

Dr. Smita Singh (Prof. and Dr. Smita Singh (Prof. and H.O.D)H.O.D)

Dr. C. Meena (Prof.)Dr. C. Meena (Prof.)

INTRODUCTION The Pulp is a specialized mesenchymal connective

tissue that occupies cavity in the central part of the teeth with in the rigid dentinal walls.

Also known as the ENDODONTIUM, consists of loose connective tissue derived from neural crest cells or the ectomesenchymal dental papilla.

Dental pulp is an unmineralized oral tissue composed of soft connective tissue, vascular, lymphatic and nervous elements that occupies the central pulp cavity of each tooth.

Pulp has a soft, gelatinous consistency.

The pulp cavities of molar teeth are approximately four times larger than those of incisors.

Each pulp cavity is distinguised into coronal pulp and radicular pulp.

The pulp cavity extends down through the root of the tooth as the root canal which opens into the periodontium via the apical foramen. And some times acessory canals & lateral canals.

The blood vessels, nerves etc. of dental pulp enter and leave the tooth through this foramen.

This sets up a form of communication between the pulp and surrounding tissue - clinically important in the spread of inflammation from the pulp out into the surrounding periodontium.

Total volume of pulp in all permanent teeth is about 0.38cc.

Single permanent tooth volume is about 0.02cc

DEVELOPMENT:-During the 8th week of intra uterine life,

there is condensation of the mesenchmye under the enamel organ-Dental papilla. (primitive pulp)

The enamel organ enlarge and enclose the dental papilla in their central portion.

Dental papilla controls the morphology & type of tooth to be formed.

Dental papilla shows :Extensive proliferation of cells.High vascularity.

Following the differentiation of the IEE into ameloblasts, odontoblast differentiate from the peripheral cells of dental papilla.

Well organized capillaries are found at beginning of dentinogenesis. (or first layer of dentin is formed.)

The cells of the dental papilla are called pulp after dentin forms around them.

BELL STAGE

Dental Pulp

Cervical loop

Anatomy Total of 52 pulp organs 32 in the permanent

and 20 in the primary teeth.

Each of these organs has a shape that conforms to that of the respective tooth.

Has ability to form dentin throughout life.(odontoblasts cells).

The pulp cavity is divided into:-

1. Coronal pulp2. Radicular pulp

ANATOMY OF DENTAL PULP

CORONAL PULPIt is the pulp occupying the pulp chamber of

the crown of the tooth.

In young teeth it resembles the shape of the outer dentin.

It has six surfaces : occlusal, mesial, distal, buccal, lingual and floor.

Pulp horns are projections into the cusp.

This pulp constricts at the cervical region where it continues as the radicular pulp

RADICULAR PULPIt is the pulp occupying the pulp canals of the

root of the tooth.

In the anterior tooth it is single and in the posterior teeth it is multiple.

The radicular portions of the pulp is continuous with the periapical tissues through apical foramen.

As age advances the width of the radicular pulp is reduced, and so is the apical foramen.

APICAL FORAMEN1. Pulp cavity terminates at

root apex as small opening called apical foramen.

2. Radicular pulp continuous with connective tissue of the periodontium through this foramen.

3. Wide open during development of root.

Sometimes apical opening is found on the lateral side of the apex.

Neurovascular bundle entering pulp through the foramen

ACCESSORY CANAL Leading laterally from the

radicular pulp into the periodontal tissue.

Formed due to entrapment of HER’S or when developing root encounters a blood vessel.

Overall occurrence is 33%

May also be present at the furcation region.

Mostly seen in apical 3rd of root.

Furcation canal

Acessory canals

Structural organisation of pulp#) PERIPHERAL REGION:-1.ODONTOBLAST LAYER2.CELL-POOR ZONE3.CELL-RICH ZONE.

#) CENTRAL REGION:-4.PULP PROPER

Structural Organization of pulp

DentinOdontoblastic zone

Cell poor zone

Cell rich zone

Pulp core proper

ZONES OF PULP

THE ODONTOBLASTIC ZONE:-

A layer of odontoblasts are found along the pulp

periphery.

They are dentin forming cells.

CELL FREE ZONE:-

It is also called Weil’s zone.

40 microns wide & relatively free of cells

This zone is found below the odontoblastic zone.

Represents the space into which odontoblasts move during tooth development.

CELL RICH ZONE:-Present in subodontoblastic layer.

Contains more proportions of fibroblast and undifferentiated mesenchymal cells.

Also contains macrophages, dendritic cells and lymophocytes.

Zone formed due to migration of cells from pulp proper.

Mitosis seen when dead odontoblasts are replaced.

PULP CORE:-

It is central region of the pulp.

Contains major blood vessels and nerve of the pulp.

Pulpal cells and fibroblasts are also seen.

This region is present in both coronal and radicular pulp.

CONTENTS OF PULP:-CELLS:-1.FORMATIVE CELLS: a) Odontoblasts b) Fibroblasts

2.DEFENSE CELLS: a) Occasional histiocytes b) lymphocytes.

3.RESERVE CELLS: - undifferentiated

mesenchymal cells

INTERCELLULAR SUBSTACE:-

1. FIBRES:- -PRECOLLAGENOUS -COLLAGENOUS.

2. GROUND SUBSTANCE.

3. BLOOD VESSELS.

4. LYMPH VESSELS.

5. NERVES .

ODONTOBLASTS:-Second most prominenet cells of pulp.

A Peripheral area of the pulp where the odontoblasts reside is termed odontogenic zone.

Arranged in Palisading pattern ,cells are tall columnar forming a layer of 3 to 5 cells in depth.

Shape may vary:- Cornal pulp - columnar

Mid portion - cuboidal Apical region –

Flat,spindle

These cells have large process extending into dentin.

Size:- 5 to 7 microns in diameter. 25 to 45 microns in length.

The no. of odontoblasts corresponds to the number of dentinal tubules.

Odontoblasts in the crown are larger than in the root.

Shape of the odontoblasts also reflect the functional activity of the cell.

During active phase, cells show basophilic cytoplasm increase in endoplasmic reticulum ,golgi appartus and secretory vesicles.(opened nucleus)

Resting (or) Non active phase cells are flattened little cytoplasm condensed chromatin and decrease no. of ER.(closed nucleus)

Cells lie very close to each other and plasma membrane of adjacent cells exhibits junctional complexes and desmosomes.

JUNCTIONAL COMPLEXNumerous junctions

such as gap junctions , tight junction and desmosomes are found between odontoblasts.

Indicating exchange of ions and small molecules.

They promote cell to cell adhension and play a role in maintaining polarity of odontoblasts

FIBROBALSTSCells that occur in greatest

number in the pulp.

Function is to form, maintain the matrix that consists of collagen fiber and ground substance throughout the life of pulp.

The fibroblasts are stellate

shaped cells having extensive process that communicate with other cell to form synytium.

H&Estain

Young teeth - Fibroblasts have abudant cytoplasm having numerous cell organells.

Older pulp - Fibroblasts appear spindle shaped posses short processes having few cytoplasmic organelles such cells are called fibrocytes.

Dual function :a) It has capability of ingesting and degrading the organic

matrix.b) Help in inflamatory and healing process by the secretion

of growth factor ,cytokines, colony stimulating factors.

UNDIFFERENTIATED MESENCHYME CELLS

These mesenchymal cells are distributed through out the pulp, frequently around the perivascular area – believed to be totipotent cell .

They are Polyhedral shaped with peripheral processes and large oval nuclei.

Under adequate stimilus they may differentiate into odontoblast or fibroblast or macrophages.

More in no. in young pulp and decreases in no. as age incrases.

DEFENSE CELLSThey play a major role local inflammation and immunity.

They are recruited from blood stream and remain as transient inhabitants in pulp These cells are

1. Macrophages or histiocytes.2. Mast cells3. Plasma cells.4.

Lympocytes,Neutrophils,Eosinophils Basophils and Monocytes.

1) MACROPHAGES :-Described as histiocytes (or) as resting wandering cells, adventitial cells.

Irregular spindle shaped cells. Small round nucleus, granular cytoplasm. And short blunt processes.

Located close to small blood vessel and capillaries.

Dark staining nucleus with cytoplasmic granules .

Macrophages are phagocytes, function of which are engulfment and digestion of foreign material.

(elimination of dead cells and removal of bacteria)

During inflammation they appear in large no. to aid in defense the organism.

In all they constitute 8-9% of the pulpal cell population.

The vesicles or phagosomes , which contain phagocytised dense irregular bodies are a characteristic feature of macrophages.

2) PLASMA CELLSPlasma cells are seen during inflammation of the pulp.

The plasma cells function in the production of antibodies.

Plasma cells may be present in coronal pulp.

They have small nuclei with radiating chromatin that appears like a cart wheel.

Peripheral arrangement of nucleus

3) MAST CELLSOccur in small groups in relation to blood vessels .

Present only during pulpal inflammation.

Have round nucleus and contain many dark staining granules in the cytoplasm.

Their number increase during inflammation.

4) LYMPHOCYTES ,EOSINOPHILS AND LEUCOCYTES

Usually found extravascularly in the normal pulp.

During inflammation they increase in number.

Lymphocyte present along the walls of blood vessels.

Involved in initial immunodefense.

Usually they are not found in uninflamed pulp

Eosinophils are present in some allergic types of inflammation.

In pulp.they are found in an inflammatory exudate.

Leucocytes are not found normally in the connective tissue.

They are transported to such sites in response to injury and then present directly in the involved tissue as well as in blood.

They phagocyte foreign material.

Dendritic cells of the pulp.cells have three or more

branched cytoplasmic processes of more

than 50 um in longitudinal length.

They are particularly rich in the periphery of the pulp (in and just subjacent to the odontoblast layer), where they compete for space with the odontoblasts and sometimes extend their processes into the dentinal tubules.

INTERCELLULR SUBSTANCE:- Intercellular substaces consist of ground substances and fibres.

It is dense and gelatinous in nature and also called as cement substances.

Supports the cell and act as medium for nutrient transport from vasculature to the cell as well as metabolites from cells to blood vessels.

FIBRES ;- (collagen & elastic) Collagen fibres are Two

types:- -precollagenous (KORFF’S

fibres (early stage) -collagenous.

Have typical cross striations called as banding at 64 nm, characteristic of collgen .

Length 10 to 100 nm or more.

Diameter 10 to 12 nm

After root completion pulp matures and bundles of collagen fibers increase in number.

They scattered throughout the coronal or radicular pulp, or they appear in bundles.These are termed diffuse or bundle collagen.

Most prevalent in root canals,especially near apical region.

The collagen fibres found in pulp are basically TYPE I &

TYPE III (55:45 ratio)

Type I: Present as thick striated fibrilsResponsible for pulp architecture

Type III:Thinner fibrils,mainly distributed in cell free and cell

rich zones Contributes to the elasticity of pulp.

Collagen turnover is maintained by fibroblasts.

During bacterial infection & inflammation,collagenolytic activity is accelerated following collagenase produced by bacteria,PMN & fibroblats.

Collagen synthesis is accelerated during reparative dentin formation.

ELASTIC FIBER:- This has the ability to expand and

contract like a rubber band.

Elastic fibers are first formed in bundles of thin micro filaments called Oxytalan fibers.

Elastin is then deposited in between oxytalan fibers.

Always associated with larger blood vessels

Elastic Fiber

FIBRONECTINIt plays a role in cell-cell & cell-matrix adhesion.

Has a major effect on the proliferation, differentiation & organization of cells.

Seen around the blood vessels.

Also found in odontoblast layer with fibers passing into predentin.

It regulates the migration and differentiation of secondary odontoblasts.

Due to its close interaction with odontoblasts and extracellular fibers,fibrinoectin helps to maintain cell morphology and provide a tight seal at this site.

Fibronectin may be involved in cell migration and anchorage in the wound healing process of the connective tissue of pulp.

Adherent property of fibronectin is due to cell surface glycoprotein receptors called Integrins

GROUND SUBSTANCEIt is a structureless mass,makes up the bulk of the pulp.

Consists of complexes of proteins,carbohydrate and water.

- Glycoaminoglycans- glycoprotiens.

- mucopolysaccharide - chondroitin A & B - hyaluronic acid.

GAG found in pulp is mainly chondroitin sulphate,dermatan sulphate & hyaluronic acid.

Proteoglycans occupy larger area and they provide protection against compression.

During dentinogenesis, the ground substance show affinity for collagen and influence fibrinogenesis.

They have capacity to bind with calcium and help in mineralisation .

Basement membrane At the epithelial-mesenchymal interface, there

exists a sheet-like arrangement of extracellular matrix proteins known as the basement membrane.

Under conventional electron microscopy, the sheet resolves into two layers: an electrondense"lamina densa" and an electron-lucent "lamina lucida“.

The basement membrane is a combined product of connective tissue and epithelium and is mainly composed of type IV collagen, the adhesive glycoprotein laminin, fibronectin, and heparian sulfate.

Besides providing anchorage, the basement membrane acts as a molecular sieve that controls the passage of molecules between epithelial cells and connective tissue.

Moreover, the basement membrane controls cell organization and differentiation by the mutual interaction of extracellular matrix molecules and cell-surface receptors.

CIRCULATION OF THE PULP The pulp organ is extensively

vascularized. They are supplied by the superior

and the inferior alveolar arteries. The blood vessels gain entry into the

pulp through the apical foramen and at times through accessory canals.

Once they reach the pulp chamber in the crown they branch out peripherally to form a dense capillary network.

Small venules drain the capillary bed and eventually leave as veins via the apical foramen.

The arterioles on entering the pulp show a reduction in thickness of vessel wall musculature and therefore lumen size increases.

Pulpal blood flow is more rapid than in most area of the body.

So pulpal pressure is highest of body tissues .

The flow of blood in arterioles - 0.3 to 1mm/sec

Venules – 0.15mm/sec

Capilaries – 0.08mm/sec

Organization of Pulp Vasculature⃟ Pulp is a micro circulatory system which lacks true arteries and veins.

⃟ The largest vessels are arterioles (50 to 100 micrometers) & venules which regulate the local interstitial environment.

⃟ They enter the tooth through the apical foramen .

⃟H&E section showing the neurovascular bundle

Apical third Middle third

PULP VASCULATURE

INNERVATION Principle role is to help in conscious recognition of irritants to the pulp, which gives the opportunity to have the problem corrected before irreversible effects can occur .

Nerve fibers, myelinated & unmyelinated(remak’s fibers), enter the tooth through the apical foramen

NERVE FIBRES

Dental pulp contains sensory and motor fibers to fulfill the vasomotor and defense function .

Sensory afferent fibers are branches of maxillary & mandibular division of trigeminal nerve.

After entering the foramen, they arborize. Larger fibers are present in the central zone. They divide as they proceed peripherally and coronally.

Subjacent to the cell rich zone, the nerves branch extensively forming a parietal layer of nerves- PLEXUS OF RASHKOW or parietal plexus or circumodontoblastic plexus. This layer contains both A and C fibers.

Types of nerve fibers

Above the cell free zone, myelinated fibers begin to lose their myelin sheath.

In the cell free zone, they form a rich network responsible for pain.

Many of these fibers pass between the odontoblastic zone.

Nerve endings may also enter the dentinal tubules

incidence - 10-20% in cusp tips 1% at the level of CEJ

They wrap around the arteries and terminate in the tunica

media.

They control the diameter of the vascular lumen & therefore

blood flow & volume & ultimately the intrapulpal pressure.

The no. of fibres in bundles varies from 150 to more than

1200.

Size of nerve fibres are less than 4 microns.

Neurotransmitters such as substance p, vasoactive intestinal

peptide, 5-hydroxytryptamine , prostaglandins,

acetylcholine, somatostatin and nor epineprine. ( change in

vascular flow.)

Nerve fibre

Morphologically it is made up of 6 different kind of nerve fibre each of which has preffered location.

1) A-beta:- - small in number. -myelinated fibres (medium size) -innervate dentin and dentin pulp

border near pulp horn tip & low affinty for nfg receptors.

- most sensitive fibres to mechanical stimulation of dentin.

A-delta fibres:- -25 to 50% - small and myelinated. - contain neuropeptide

CGRP(CALCITONIN GENE RELATED PEPTIDE) and express receptors for NGF.

- innervate dentin, predentin , odontoblast layer in coronal region underlying enamel.

- conc. In dentin near pupl horn tip, less prevalent in cervical region , least in root dentin.

- therefore specific gradient of innervation.

C-fibres:- - unmyelinated and majority in no.

- They are polymodal and responsive to capsaicin and to inflammatory mediators such as histamine and bradykinin.

- They terminate in peripheral pulp

or along blood vessels, and they are mostly activated by pulpal damage .

- Some dental C-fibers respond to intense heat or cold, it is not clear that they differ from the polymodal receptors.

Activation mechanisms of intradental nerve fibers

On the basis of the single-fiber recordings it can be concluded that activation of only a small number of pulpal afferents is needed to evoke prepain or pain sensations.

This is clinically important because it suggests that pulp testing may produce a false-positive response, even in teeth with extensive pulpal necrosis, as long as at least some pulpal axons are still responsive.

This could explain the clinical observation of a positive pulpal response in a tooth with a periradicular radiolucency.

It has been suggested that non-noxious mechanical (tactile) stimulation of the intact tooth crown activates pulpal A-beta fibers.

On the basis of such findings, those fibers were regarded as a discrete functional group that would be involved with the regulation of masticatory functions and the sensation of food texture between the teeth.

However, A-beta and Adelta fibers show similar responses to various external stimuli and to inflammatory mediators,and the results suggest that the fibers belong to the same functional group.

The pulpal C-fibers are polymodal because they respond to several different modes of stimulation and have high thresholds for activation.

They are activated only if stimuli reach their terminal endings inside the pulp. In an intact tooth, given the insulating enamel and dentinal layers, rather intense thermal stimuli are needed for their activation.

They also respond to histamine and bradykinin applied to the exposed pulp, which indicates that this fiber group also may be activated in connection with pulpal inflammatory reactions.

Thus,the dull pain induced by pulpitis may be evoked by C-fiber activation.

The application of intense heating or cooling to human teeth produces a sharp pain sensation with a short latency, typically within a few seconds.

If the stimulation is continued, a dull, radiating pain response

follows.

The first response is an immediate or short-latency firing of intradental A-fibers, followed by a delayed Cfiber activation.

The initial A-fiber responses are supposedly induced by the dentinal fluid flow resulting from the rapid temperature

changes.

The delayed C-fiber activation is probably induced by a direct effect of heat and cold on the nerve endings in the pulp.

The results of these thermal stimulation studies strongly indicate that intradental A- and Cfibers may mediate different perceptual qualities of dental pain, i.e, sharp and dull, respectively.

In addition, certain other stimuli, such as air drying of exposed dentin and bradykinin applied to the exposed pulp, which are known to activate selectively pulpal A- or C-fibers, are also able to induce either sharp or dull pain, respectively, in human experiments.

According to the hydrodynamic theory, rapid dentinal fluid flow serves as the final stimulating intradental nociceptors for many different types of stimuli.

In support of this hypothesis, single intradental A-fibers respond to a number of different hydrodynamic stimuli including dentinal

probing, air blasts, and hyperosmotic solutions .

Studies conducted in vitro demonstrate that all these stimuli induce fluid flow in the dentinal tubules.

It is the osmotic strength of solutions and not their chemical composition that elicit pain responses in human teeth, nerve responses , and fluid flow responses in dentinal tubules.

Allodynia and Hyperalgesia

Hyperalgesia is defined as an increase in the perceived magnitude of a painful stimulus.

Allodynia is defined as a reduction in pain threshold so that previously non-noxious stimuli are perceived as painful.

Conclusion of innervation. A review of the mechanisms of pulpodentinal pain

has numerous clinical implications.

1.Dentinal pain is primarily due to myelinated fibers innervating dentinal tubules where fluid movement is detected and signaled back to the brain. Therapeutic reduction of dentinal fluid movement or neuronal activation can reduce dentinal hypersensitivity.

2. Second, inflammation is detected by receptors expressed on pulpal nociceptors; the binding of inflammatory mediators onto these receptors can activate or sensitize these nociceptors. Drugs that reduce tissue levels of inflammatory mediators (eg, NSAIDs) relieve pain by reducing activation of these receptors.

3. Hyperalgesia and allodynia can occur during pulpal and periradicular inflammation. Evaluation of the presence of these altered pain states provides the biologic basis for endodontic diagnostic tests.

4. Hhyperalgesia and allodynia can occur by both peripheral and central mechanisms, and may persist beyond the dental appointment. Thus, patients with preoperative pain have an increased risk of experiencing postoperative pain.

5. Referred pain is due, in part, to convergence of multiple sensory fibers onto the same central projection neuron.

6. Pulp testing,using either electrical or thermal stimuli requires an appreciation of the mechanisms involved for proper interpretation of tooth and patient conditions, and for minimization of potential confusion due to false positive or false negative results.

FUNCTIONS OF DENTAL PULP INDUCTIVE FORMATIVE NUTRITIVE PROTECTIVE OR SENSORY DEFENSE OR REPARATIVE

INDUCTIVE It induces oral epithelial differentiation into dental lamina

and enamel organ.

It also induces the enamel organ to differentiate into a

particular type of tooth morphology.

Therefore in the development of tooth the pulp precursor has important role to play.

FORMATIVEThe cells of Pulp induces dentin matrix formation which surrounds and protect the pulp.

By the development of odontoblastic process the dentin is formed at the pulp-predentin border and along the tubule wall.

This involves formation of primary and secondary dentin.

NUTRITIVE Dental pulp maintains the vitality of dentin by providing O2 and nutrients to the odontoblasts.

Also provides continuing source of dentinal fluid.

Nutrition made possible by rich peripheral capillary network.

PROTECTIVE or SENSORY Pulp helps in recognition of stimuli like heat, cold, pressure, chemicals by way of sensory nerve fibres.

Vasomotor innervation controls the muscular wall of blood vessels.This regulates the blood volume and rate of blood flow and hence the intrapulpal pressure.

DEFENSIVE (OR) REPARATIVE Pulp has remarkable reparative abilities. It responds to irritation by producing

reparative dentin and mineralizing affected dentinal tubules.

Mild to moderate irritation results in continued peritubular dentin formation, sclerosis and intratubular calcifiction- (Tublar sclerosis).

Stimuli like operative procedures abrasion, caries can result in rapid dentin formation (Tertiary dentin).

Inflamed pulp due to bacterial infection the cells in pulp aid in the process of repair (macrophages, lymphocycts, neutrophils, monocytes, plasma , mast cells).

REGRESSIVE CHANGES (AGING)Cell Changes Appearance of fewer cells in aging pulp.

Cells are characterized by a decrease in size and no of cytoplasmic organelles .

Fibroblast exhibit less perinuclear cytoplasm, long thin cytoplasmic processes.

Intra cellular organelles are reduced in no. and size.

FIBROSIS Diffuse fibrillar

componentsAccumulation of both

Bundles of collagen fibres

Fiber bundles may appear arranged longitudinally in the radicular pulp and more diffuse in coronal pup.

Collagen accumulation also occurs in some older pulps.

Increase in fibers in the pulp organ is gradual and generalized

External trauma such as dental caries (or) deep restorations cause a localized fibrosis (or) scarring effect.

Increase in collages fibers decrease in the size of the pulp.

Vascular changes occur in aging pulp.

Atherosclerotic plaques may appear in pulpal vessels.

Calcifications are found that surround vessels.

Calcification is found most often in the region near the apical foramen.

Pulp Stones (denticles) Pulp stones are calcified , shiny , nodular

masses that occur either single or multiple in no. within the coronal and radicular pulp.

Develop in teeth that appear to be normal in other respects.

Usually asymptomatic unless they impinge on nerves (or)blood vessels.

Seen in functional as well as embedded unerupted teeth.

They start as very small bodies .

They may gradually grow and become large and impinge on nearby structures.

The pain can be mid to severe neuralgic type of pain.

Pain disappears after this pulp stones are removed by pulpotomy or pulpectomy.

Large pulp stones are seen radiographically, and histologically both small and large stones can be seen.

Pulp stones according to histological structures have been classified into two types:-

1) true pulp stones.

2) false pulp stones.

True pulp stones :- True denticles are similar in structure to

dentin.

They have dental tubules and contain processes of the odontoblasts.

Development of true denticles is caused by the inclusion of remnants of the epithelial root sheath with in the pulp.

Epithelial remnants induce the cells of pulp to differentiate into odentoblasts then form the dentin mass.

H&E section

False pulp stones or denticles:-

They do not exhibit dentinal tubules..

They appear as concentric layers of calcified tissue.

Some cases these calcification sites appear within a bundle of collagen fibers.

Some cases they appear in pulp free of collagen accumulations.

Some cases arises around vessels.

Center of these concentric layers of calcified tissues there may be remnants of necrotic and calcified cells.

Calcification of thrombi in blood vessels called phleholiths, may also serve as nidi for false denticles.

An denticles begin as small nodules but increase in size by incremental growth.

Classified as free, attached (or) embedded depending on their relation to the dentin:-

a) Free denticle – entirely surrounded by pulp tissue.

b) Attached denticle – Partly fused with the

dentin.

c) Embedded denticles – Entirely surrounded by dentin

Incidence as well as the size of pulp stones increase with age.

Attached pulp stone.

False Denticle

False calcification seen along the walls of the blood vessel

Diffuse Calcifications:-Appear as irregular calcific deposits in the

pulp tissue, following collagenous fiber bundles, blood vessels.

Sometimes they develop into larger mass, persist as calcified spicules.

These calcifications are usually found in the root canal and less often in coronal area.

These calcification surrounds blood vessels.

These calcifications may be called as dystrophic calcification

Diffuse calcification

Diffuse calcification of the pulp, seen along with pulp fibrosis

CLINICAL CONSIDERATIONS1) Shape of the pulp chamber and its extensions

into the cusps pulpal horns is important.

2) Wide pulp chamber into tooth of young person will make a deep cavity preparation hazardous.

3) The pulpal horns project high into the cusps exposure of pulp can occur.

4) If opening a pulp chamber for treatment its

size and variation in shape must be taken into

consideration

5) Age advance , the pulp chamber becomes smaller difficult to locate the root canals. (to overcome this problem one should proceed distal root in lower molar and palatal root in maxillary molar as this canals are wider and easier to locate.)

6) Shape of the apical foramen and its location may play an important part in treatment of root canals.

7) Accessory canals, and multiple canals are rarely seen in radiographs.

8) The acessory canals and furcation canals play important role in endo – perio lesion.(spread of infection).

9. Preparing teeth for restorations generates frictional heat, which causes dehydration and tissue damage to the pulp.

Such injury is lessened by proper water irrigation during the cutting procedure.

ANATOMIC CONSIDERATIONS

Pulp Chamber with stone Cervical horns

Sproles discovered never-before-reported cervical pulp horns.

Found 66.8 to 96.3% of the time in the first and second molar teeth , this extra pulp horn presents a real danger in cavity preparation.

High incidence of pulp sensitivity in these teeth, following gingival recession or Class V or full-crown restoration, could well be related to the very close proximity of these “extra” pulp horns.

cervical pulp horns

Dehydration.Brännström documented the damaging

effects on the pulp by dehydration of the exposed dentin.

Constant drying and chip blowing with warm air during cavity preparation under the

rubber dam might well contribute to pulp inflammation and the possible necrosis that sometimes follows restorative dentistry,

particularly in an already “stressed pulp.”

Pin InsertionSince the advent of pin placement into the

dentin to support amalgam restorations, or as a framework for building up badly broken

down teeth for full-crown construction, an increase in pulp inflammation and death has been noted.

Undoubtedly, in some cases, the trauma of preparing and inserting the pins is insult enough to finish off an already stressed pulp.

In other cases, however, the pins may have been inadvertently inserted directly into the pulp or so close to it that they acted as a severe irritant

Impression Taking Seltzer et al. showed that damaging pulp

changes may develop when impressions are taken under pressure.

Bacteria placed into a freshly prepared cavity were forced into the pulp.

Moreover, the negative pressure created in removing an impression may also cause odontoblastic aspiration.

PULP PAIN Pulp pain, or pulpalgia, is by far the most

commonly experienced pain in and near the oral cavity and may be classified according to the degree of severity and the pathologic process present:

1. Hyperreactive pulpalgia a. Dentinal hypersensitivity b. Hyperemia 2. Acute pulpalgia a. Incipient b. Moderate c. Advanced

3. Chronic pulpalgiaa. Barodontalgia4. Hyperplastic pulpitis5. Necrotic pulp6. Internal resorption7. Traumatic occlusion

PATHOPHYSIOLOGY OF PULPAL DISEASE INSULT (local) Deep caries or drilling)

INFLAMMATION (Local)

Release of inflammatory agents Reduction of vascular reactivity VASODILATION Increase permeability

Increased resistance of venules

Local Pulp Necrosis

Total Pulp Necrosis

PULP IRRITANTS1. DISEASE PROCESS:- -caries, trauma, attrition, abrasion,

erosion.2. MECHANICAL IRRITATION:- - excessive heat, pressure, dessication.3. CHEMICAL COMPONENTS:- - acid contents of cements and

etchents4. THERMAL:- - metaalic restoration conduct

temprature changes.5. MICROLEAKAGE.

THERAPEUTIC MEASURES(VITAL PULP THERAPY)PULP CAPPING:- -DIRECT PULP CAPPING -INDIRECT PULP CAPPING

DIRECT PULP CAPPINGSometimes pulp may get exposed either due

to caries trauma or as a result of iatrogenic errors during operative procedures.

Direct pulp capping is a technique for treating an exposed pulp with a material that seals the exposure site and promotes reparative dentin formation .

Consideration:-

- duration of the pulpal exposure to the oral enviroment.

- comparing various pulp capping material and their ability to seal .

.

1. Size of pulp exposure- less than 1 mm

2. Presence of dentinal chips :- some - belilive that dentinal chips

encourage the dentinal bridge formation. other – this dentinal chips can forced

deeper into pulp tissue and later may produce pulpitis and abscess formation.

3. Control for hemorrhage and plasma exudate:-

- pulp capping agent should never be placed against bleeding pulp or a clinically observed blood clot.

- operative trauma evoke very rapid

changes in dental pulp leading to permeation and leakage of plasma protiens out of dentinal

tubules to the cut surface and such leakage could inhibit wound healing (dentinal bridge formation.)

4. Impaction of pulp capping agent:- -ideally the agent should be placed gently

on to exposed surface and not into the deeper pulpal tissues.

5. Embolization of pulp capping agent:- - if open or cut vessels are present

venules can carry capping material deep into pulp.

- Ca(OH)2 of high pH-produce perivascular foci of mummification and inflamation.

- Ca(OH)2 oflow pH block the vessels and decrese the pulpal blood flow which leads to delayed or inadequate healing.

DIRECT PULP CAPPING

INDIRECT PULP CAPPINGIn deep carios lesion where complete removal

of carious dentin may result in pulp exposure , the deepest layer may be intentionally left behind .

Therefore indirect pulp capping is a deliberate retention of thin layer of dentin nea the pulp and medication of remaining dentin with calcium hydroxide.

INDIRECT PULP CAPPING

EFFECT OF DENTAL MATERIALS ON PULP Silicate cements :- - Have long been condemned

both clinically and histologically as a pulp irritant. - Because of this and their relative

impermanence, silicates gradually slid into disfavor and disuse.

Zinc phosphate:- - Because of the high percentage of

unincorporated phosphoric acid, patients may suffer severe pain with cementation, the so-called “phosphoric acid sting.”

- This is owing to the low pH of the mix and the hydraulic pressure of forcing the casting to place, which forces the acid into the dentinal tubules. A severely stressed pulp may not recover from this initial chemical shock.

COMPOSITE RESINS:- causes pulp

inflammation, Pulp protection is therefore recommended.

Calcium hydroxide – includes dentin bridge formation.

Gold Foil and Cast Alloys:- - Potential pulpal reactions due to

condensation.

Amalgam restorations,- - In general, have been considered to be either

inert or only mildly irritating to the pulp. - Any pulpal response to amalgam seems to be

related mainly to the physical insertion of the amalgam, that is, the pressure of condensation.

Dentin bonding agent – can irritate the pulp causing inflammation .

GIC – Well tolerated by pulp . It is thought that the relatively good adhesion of this material accounts for its high biocompatibility. Leakage appears to be largely prevented and, thus, invasion of bacteria at the tooth-filling interface is minimized.

Early pulpal reactions, although less than with cements or composite resins, and with rapid recovery.

Composition guards against permeation of material through the dentinal tubules to the pulp.

When used as luting agent, liners are advocated .

Hydraulic pressure and etching during placement may irritate the pulp .

Gold Foil and Cast Alloys:- - Potential pulpal reactions due

to condensation.

Zine oxide – eugenol- has an anti-bacterial effect.

-In the pulp it reversibly inhibits prostaglandin synthetase activity (anti-inflammatory action).

-In addition, the ZOE may form a temporary seal against bacterial invasion

DETECTION OF PULP VITALITYElectric pulp testing.

Thermal testing- Heat testing Cold testing.

Anesthetic testing.

Test cavity.

Bite test.

RECENT ADVANCES:-

- Laser doppler flowmetry. - Transmitted light

photoplathysmography - Pulp oximetry. - Dual Wavelength Spectrophotometry.

Cold testing Cold can be

applied to teeth in the form of an ice stick made using a needle cover, carbon dioxide snow, ethyl chloride on a pledget of cotton wool, cold water and rubber Dam .

COLD AIR, ETHYL CHLORIDE, DRY ICE,ICE, FREON.

Heat testing An electric heater-tip,

rubber wheel, or hot gutta percha can be used

When using hot gutta percha it is wise to have local anaesthetic to hand and to cover the tooth surface with petroleum jelly to prevent the sticky rubber from adhering to the tooth

Isolating teeth individually with rubber dam and applying hot tap water in a syringe is an excellent method of testing individual teeth when diagnosis is difficult or if a patient describes the pain as being stimulated by a hot drink.

Electric pulp testing Electric pulp testers use an

electric current (AC or DC) to stimulate a response from the nerve tissue in the pulp.

An example is the Analytic Technology pulp tester .The unit switches on automatically when a circuit is made.

The current at the tip is then increased by a microprocessor until the circuit is broken or maximum current is reached.

A digital readout from 0 to 80 is given on an LED display. It is possible to increase ordecrease the rate of electrical stimulus.

Anesthetic testing

Applying local anaesthetic as an intraligamental injection may help elicit the offending tooth.

Teeth adjacent to the injection site may also be affected by the

anaesthetic.

This method could be used to identify whether a maxillary or mandibular tooth is the cause of referred pain.

Test cavityAs a last resort a cavity can be cut in the

tooth with no local anaesthetic.

This is not totally reliable, however, as sometimes partially necrotic pulps in teeth that require root canal treatment will respond to drilling.

Pulp oximetryThe pulse oximeter is a non-invasive oxygen

saturation monitoring device widely used in medical practice for recording blood oxygen saturation levels during the administration of intravenous anesthesia.

This device is currently under investigation in dental practice to detect pulpal blood circulation by virtue of its non-invasive and atraumatic nature.

Specific objectives were to develop a design for dental sensor (a modified finger probe) that can be successfully applied and adapted to the tooth and well suited to detect pulsatile absorbance.

Laser doppler flowmetryLaser Doppler Flowmetry (LDF) is a

noninvasive, electro optical technique, which allows the semi-quantitative recording of pulpal blood flow.

The Laser Doppler technique measures blood flow in the very small blood vessels of the microvasculature.

The technique depends on the Doppler principle where by light from a laser diode incident on the tissue is scattered by moving RBC's and as a consequence, the frequency broadened.

Dual Wavelength SpectrophotometryThis method measures oxygenation changes

in the capillary bed rather than in the supply vessels and hence does not depend on a pulsatile blood flow.

CONCLUSIONTHE PRESERVATION OF A HEALTHY

PULP DURING OPERATIVE PROCEDURES AND SUCCESSFUL MANAGEMENT IN CASES OF DISEASES ARE TWO OF MOST IMPORTANT CHALLENGE TO THE CLINICAL DENTIST.

REFERENCES DENTAL PULP; Seltzer & bender.

ORAL HISTOLOGY ANDEMBROLOGY; Orban’s

ORAL HISTOLOGY; Tencate

PATHWAYS OF THE PULP; Cohen

ENDODONTIC PRACTICE; Grossman

ENDODONTICS;Ingle

ENDODONTIC PRACTICE;Weine