New Dental Pulp

DENTAL PULP

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CONTENTS  INTRODUCTION  EMBROLOGY  ANATOMY  STRUCTURAL ORGANISATION OF PULP  CELLS OF PULP  EXTRA CELLULAR MATRIX  CIRCULATION OF PULP www.rxdentistry.blogspot.com

 METABOLISM OF PULP  INNERVATION OF PULP  FUNCTIONS OF PULP  PULP OF DECIDUOUS TOOTH  PULP CALCIFICATION  AGE CHANGES  CLINICAL SIGNIFICANCE  CONCUSION www.rxdentistry.blogspot.com

INTROUDCTION • The Pulp is a soft mesenchymal connective tissue that occupies pulp cavity in the central part of the teeth. • It is a special organ because of the unique environment

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DEVELOPMENT • During the 8th week of IUL, there is condensation of the mesenchmye under the enamel organDental papilla. • 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 www.rxdentistry.blogspot.com

• 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

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• Capillaries crowd around the odontoblast during active dentinogenesis • Rim of the enamel organ (IEE & OEE) is the cervical loop. • Root formation is carried out by the proliferation of cells at the cervical loop.

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Dental Papilla

Dental papilla capped by the enamel organ www.rxdentistry.blogspot.com

GENERAL FEATURES • Total of 52 pulp organs 32 in the permanent and 20 in the primary teeth. • Total pulp volume in permanent teeth is 0.38cc with mean being 0.02CC • Each of these organs has a shape that conforms to that of the respective tooth. • Has ability to form dentin throughout life www.rxdentistry.blogspot.com

The pulp cavity is divided into 1. 2.

Coronal pulp Radicular pulp

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CORONAL PULP • It 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 www.rxdentistry.blogspot.com

RADICULAR PULP • It 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. www.rxdentistry.blogspot.com

APICAL FORAMEN 1. 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. Diameter in an adult- maxillary teeth-0.4mm mandibular teeth-0.3mm 4. Wide open during development of root www.rxdentistry.blogspot.com

APICAL FORAMEN 5. Undergoes changes I. Tooth may tipped from horizontal pressure cause apex to tilt in opposite direction, exert pressure on one wall of the foramen causing resorption 6. Same time cementum laid down on opposite side resulting relocation of the original foramen www.rxdentistry.blogspot.com

7. Sometimes apical opening is found on the lateral side of the apex 8. There may be 2-3 foramina split by cementum or dentin- APICAL DELTA

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Apical Foramen

Neurovascular bundle entering pulp through the foramen www.rxdentistry.blogspot.com

ACCESSORY CANAL • Leading laterally from the radicular pulp into the periodontal tissue. • Present in the apical third of the root sheath cells • Formed due to premature loss of HERS or when developing root encounters a blood vessel. • Overall occurrence is 33% • May also be present at the furcation region

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Accessory Canals

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Structural Organization of pulp

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HISTOLOGICAL ZONES OF PULP ODONTOBLAST LAYER CELL-POOR ZONE CELL-RICH ZONE PULP PROPER

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THE ODONTOBLASTIC ZONE A layer of odontoblasts are found along the pulp periphery. They are dentin forming cells.

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 CELL FREE ZONE • It is also called weil’s zone • 40 microns wide &relatively free of cells • Traversed by • blood vessels • unmyelinated nerves • cytoplasmic process of fibroblasts • This zone is found below the odontoblastic zone • Represents the space into which odontoblasts move during tooth development.

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CELL RICH ZONE Present in subodontoblastic layer Contains more proportions of fibroblast and undifferentiated mesenchymol 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 Also contain young collagen fibres during early dentiogenis. www.rxdentistry.blogspot.com

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

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CELLS OF PULP  ODONTOBLASTS  FIBROBLASTS  UNDIFFERENTIATED CELLS  DEFENSE CELLS

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ODONTOBLASTS A Peripheral area of the pulp where the odontoblasts reside is termed odontogenic zone. Arranged in Palisading pattern cells one tall columnar forming a layer of 3 to 5 cells in depth. Shape may vary cornal pulp- columnar midportion - cuboidal Apical region - Flattened www.rxdentistry.blogspot.com

These cells have large process extending into dentin The no of odontoblasts corresponds to the number of dentinal tubules Average no of odontoblasts estimated to 45,000 per Sq.mm of odontogenic zone. Odontoblasts in the crown are larger than in the root. www.rxdentistry.blogspot.com

Shape of the odontoblasts also reflect the functional activity of the cell. During active phase, cells show increase in endoplasmic reticulum golgi appartus and secretory vesicles. Resting (or) Non active phase cells are flattened little cytoplasm condensed chromatin and decrease no of ER

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JUNCTIONAL COMPLEX Numerous 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 www.rxdentistry.blogspot.com

JUNCTIONAL COMPLEXES

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ODONTOGENIC PROCESS  Odontoblasts give off a single process that extends into dentin and housed within dentinal tubules These process devoid of major organelles They contain abundance of microtubular filaments and coated vesicles Mainly composed of protein-tubulin, act in and vimentin www.rxdentistry.blogspot.com

FUNCTIONS OF ODONTOBLASTS Synthesis of organic matrix Synthesis of non collagenous substances like sialoprotein, phosphophoryn, osteocalcin, ostenoectin & osteopontin Intracellular accumulation of calcium Degradation of organic matrix

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FIBROBALSTS Cells that occur in greatest number in the pulp Function is to form, maintain the matrix that consists of collages, fiber and ground substance throughout the pulp The fibroblasts are stellate shaped cells having extensive process. www.rxdentistry.blogspot.com

Fibroblast

H&Estain

Immunohistochemical www.rxdentistry.blogspot.com method

Young teeth - Fibroblasts have abudant cytoplasm having numerous cell organcells. Older pulp - Fibroblasts appear spindle shaped posses short processes having few cytoplasmic organelles such cells are called fibrocytes www.rxdentistry.blogspot.com

Dual function : a) It has capability of ingesting and degrading the organic matrix. b) Pathway of both synthesis and degreadation in the same cell.

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UNDIFFERENTIATED MESENCHYME These mesenchymal cells are distributed through out the pulp, frequently around the perivascular area - believed to be toti potent cell They are Polyhedral shaped with peripheral processes and large oval nuclei Difficult to differentiate from fibroblast under light microscopy Under adequate stimilus they may differentiate into odontoblast or fibroblast or macrophages. In older pulp,their number and ability to differentiate comes down www.rxdentistry.blogspot.com

IMMUNOCOMPETENT CELLS They 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 2. Mast cells 3. Plasma cells 4. Lympocytes,Neutrophils,Eosinophils basophils and manocytes. www.rxdentistry.blogspot.com

MACROPHAGES IN PULP Described as histiocytes (or) as resting wandering cells Located close to blood vessel Have several phenotypes Macrophages are phagocytes,function of which are engulfment and digestion of foreign material During inflammation they appear in large no to aid in defense the organism In all they constitute 8-9% of the pulpal cell population www.rxdentistry.blogspot.com

Macrophages

Dark staining nucleus with cytoplasmic granules www.rxdentistry.blogspot.com

PLASMA CELLS • Plasma 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 cast wheel. www.rxdentistry.blogspot.com

Plasma Cell

Peripheral arrangement of chromatin in nucleus www.rxdentistry.blogspot.com

MAST CELLS Occur 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.

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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

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Eosinophils are present in some allergic types of inflammation In pulp.they are found in an inflammatory exudate.

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LYMPHOCYTES IN PULP

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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 .

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EXTRACELLULAR MATRIX Connective tissue fibers Collagen Elastin Fibronectin

Ground substance Proteoglycans Glycosaminoglycans

Basement membrane www.rxdentistry.blogspot.com

FIBRES (COLLAGEN FIBRES) Extra cellular structural protein,major constituent of connective tissue Collagen fibers appear throughout the pulp young fine fibers ranging in diameter from 1012mm. Pulp collagen fibers do not contribute to dentin matrix production.

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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.

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Collagen Fiber

Seen in relation with fibroblasts

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Type I:  Present as thick striated fibrils Responsible for pulp architecture Type III:  Thinner fibrils,mainly distributed in cell free and cell rich zones  Contributes to the elasticity of pulp

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Type IV: Present along the basement membrane of blood vessels Type V and VI: Seen to form dense meshwork of thin microfibrils through out the stroma

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• 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

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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

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Elastic Fiber

Verhoeff's method stains the fibers black www.rxdentistry.blogspot.com

FIBRONECTIN It 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

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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. It regulates the migration and differentiation of secondary odontoblasts Adherent property of fibronectin is due to cell surface glycoprotein receptors called Integrins www.rxdentistry.blogspot.com

GROUND SUBSTANCE It is a structureless mass,makes up the bulk of the pulp Consists of complexes of proteins,carbohydrate and water. Broadly classified as  Glycoaminoglycans  Proteoglycans

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GLYCOSAMINOGLYCANS 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 www.rxdentistry.blogspot.com

BASEMENT MEMBRANE It is a sheet like arrangement of extra cellular protein matrix at the epithelialmesenchymal interface Composed of 2 layers  lamina densa-electron dense  lamina lucida-electrolucent

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Basement membrane is a product of connective tissue and epithelium It is composed of  Collagen type IV  Laminin-adhesive glycoprotein  Fibronectin  Heparin sulfate

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Collagen IV provides binding sites for the rest of basement membrane components Laminin binds to both cells of connective tissue and epithelium In mature pulp,basement membrane forms interface along endothelial cells & schwann cells

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FUNCTIONS Act as sieve between epithelium and connective tissue Helps in organisation and differentiation by enabling interactions between extra cellular molecules and cell surface receptors Eg: Odontoblasts during tooth development www.rxdentistry.blogspot.com

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 foramen.

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The arterioles on entering the pulp show a reduction in thickness of vessel wall musculature and therefore luman 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 asterioles - 0.3 to 1mm/sec Venules – 0.15mm/sec Capilaries – 0.08mm/sec

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Organization of Pulp Vasculature ⃟Pulp is a micro circulatory system which lacks true arteries and veins ⃟The largest vessels are arterioles & venules which regulate the local interstitial environment ⃟They enter the tooth through the apical foramen ⃟Pulp tissue pressure is 14cm H20 www.rxdentistry.blogspot.com

Organization of pulp vasculature

H&E section showing the neurovascular bundle

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 ARTERIOLES: Arterioles (50µ diameter) Terminal arterioles Precapillaries Metarterioles Capillaries (8µ) www.rxdentistry.blogspot.com

The branching point of terminal arterioles is characterized by smooth muscle clumps that act as sphincters which are under the local cellular & neuronal control Thus pulpal inflammation elicits a localised circulatory response restricted to the area of inflammation Arteriolar pressure – 43mm Hg.

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PULP VASCULATURE

Apical third

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Middle third

Microcirculatory System

Arterioles & venules www.rxdentistry.blogspot.com

 CAPILLARIES • Function as exchange vessels regulating the transport of diffusion of substances between blood and local interstitial tissue elements • They consists of single layer of endothelium surrounded by basement membrance • Capillary pressure –35 mmHg • Capillary wall is 0.5µ thick & acts as semipermeable membrane

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Based on the property of semi permeability capillaries may be grouped as Class I : Fenestrated capillaries Class II: Continuous capillaries (non fenestrated) Class III : Discontinuous capillaries Class IV : Tight junction capillaries Class I & II are present in the dental pulp www.rxdentistry.blogspot.com

Capillary network is organized in 3 layers 1. Terminal capillary network located in the “odontoblastic layer” 2. “Capillary network” present adjacent to the odontoblastic layer & consists of pre capillary & post capillary vessels 3. Venular network of vessels During aging & decreased metabolism these layers appear as single layer

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SEM shows extensive arborization of capillaries from the metarterioles

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VENULES Collecting venules receive pulpal blood flow from the capillaries & transfer it to the venules Arterio-venous anastomosis permits direct shunting from arterioles to venules Venular pressure –19mm Hg

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LYMPHATICS Lymphatic vessels are formed from fine meshwork of small, thin walled lymph capillaries Lymph capillaries coalesce to form larger lymphatic vessels with valves They start as blind openings near Weil’s zone & odontoblastic layer The larger lymphatic vessels run along the blood vessels & nerves

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Multiple collecting lymph vessels exit though the apical foramen & drain lymph from pulp into the periodontium Role in pulp: They remove high molecular solutes from the interstital fluids thus maintain interstitial COP They transport lymph to the regional lymph node before it enters into the blood vessels. This provides an immuno surveillance function. www.rxdentistry.blogspot.com

METABOLSIM • Metabolism has been studied by measuring the rate of O2 consumption & production of Coz lactic acid by pulp tissue • Radiospriometry is also used to evaluate the metabolism. Pulp tissue is placed in 14C labeled substractures, such as succinate & rate of apperance of CO2 is measured. • During dentinogenesis, rate of O2 consumption is high than after crown completion. www.rxdentistry.blogspot.com

• Greatest metabolic activity is seen in the odontoblast layer. • Reduced pH of pulp causes decreases in O2 consumption as in pulp abscess. • In addition to the glycolytic pathway, the pulp has the ability to produce energy through Pentose shunt pathway, suggesting that the pulp can function under varying degrees of ischemia

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• Several dental materials have shown to inhibit O2 consumption Eg. ZOE , Ca(OH)2 & silver amalgam • Pulpal irritation causes increases in cycloxygenase products, which is inhibited by ZOE • As cellular composition reduces, the rate of oxygen consumption decreases.

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INNERVATION Principles 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, mylinated & unmyelinated, enter the tooth through the apical foramen

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INNERVATION

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.

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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-NERVE PLEXUS OF RASHKOW. This layer contains both A and C fibers.

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Types of nerve fibers

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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 In the cell free zone, they form a rich network responsbile for pain. Many of these fibers pass between the odontoblastic zone.

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Nerve endings may also enter the dentinal tubules incidence - 10-20% in cusp tips 1% at the level of CEJ Motor nerves are supplied by the sympathetic division of autonomic nervous system.

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• 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.

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Fiber A-alpha (α) A-beta(β )

Table 3.2 Classification and function of fibers in peripheral nerves Diameter Conduction velocity Function (speed of impulse, (µm) m/sec) 6-20 15-80 (myelinated) Afferent fibers for touch, pressure 5-12 30-70 proprioception, vibration (mechanorecptors)

A-gamma(µ) A-delta (δ) B

1-5 1-3

2-30 (myelinated) 3-15 (myelinated)

C

04-1.0

0.4-2(unmyelinated)

Afferent fibers for pain and temperature Visceral afferent fibers preganglionic visceral efferent fibres Afferent fibers for pain and tempature; post ganglionic visceral efferent fibers

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Neuropeptides in Pulp Neuropeptides are proteins that have been associated with central & peripheral nervous system Following are the neuropeptides demonstrated in pulp : Originate from trigeminal ganglion (C fibres) Substance P CGRP Neurokinin A www.rxdentistry.blogspot.com

FUNCTIONS OF DENTAL PULP –

– – – –

INDUCTIVE FORMATIVE NUTRITIVE PROTECTIVE DEFENSE www.rxdentistry.blogspot.com

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

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FORMATIVE The cells of Pulp induces dentin formation This involves formation of primary and secondary dentin. The primary dentin is tubular and regularly arranged.Formed before root closure Secondary dentin contain fewer tubules and is formed after root closure.

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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.

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PROTECTIVE 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.

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DEFENSIVE (OR) REPARATIVE  Pulp as remarkable reparative abilities It responds to irritation by producing reparative dentin and mineralizing and affected dentinal tubules. Mild to moderate irritation results in continued peritubular dentin formation, sclerosis and intratubular calcifiction(Tublar sclerosis)

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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)

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PULP OF DECIDUOUS TEETH • Overall dimensions smaller • Pulp chambers larger • Roots are long and slender and root canals narrower and follow a tortuous course • Pulp horns at a higher level, especially mesial horns of primary molars • Resorption starts soon after root completion • Root resorption and dentin deposition changes size shape and number of root canals.

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PRIMARY PULP ORGAN • Primary pulp functions for a mean of 8.3 years. This time can be divided into three periods Pulp organ growth Time of crown and root development Pulp maturation (3 years, 9 months) Time after root completion to beginning of root resorption Pulp regression (3 Years , 6 months) Beginning of root resorption to exfoliatin

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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  Active pulpal fibrocyte (or) fibroblast has abundant rough-surfaced endoplasmic reticulum notable golgi complex, numerous mitochondria

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 Fibroblast exhibit less perinuclear cytoplasm, long thin cytoplasmic processes.  Intra cellular organelles are reduced in no and size

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FIBROSIS Diffuse fibrillar components

 Accumulation 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 www.rxdentistry.blogspot.com

 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

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Pulp Fibrosis

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 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.

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Pulp Stones(denticles)  Appearing in either or both coronal and root portions of the pulp organ  Develop in teeth that appear to be normal in other respects.  Asymptomatic unless they impinge on nerves (or)blood vessels  Seen in functional as well as embedded unerupted teeth.

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Classification 1. True denticles 2. False denticles 3. Diffuse calcifications

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True denticles True denticles are similar in structure to dentin They have dental tubules and contain processes of the odontoblasts Usually located close to the apical foramen

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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.

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True Denticle

• H&E section of true denticle

• Higher magnification www.rxdentistry.blogspot.com

False 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

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 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

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 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. www.rxdentistry.blogspot.com

False Denticle

False calcification seen along the walls of the blood vessel www.rxdentistry.blogspot.com

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

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 These calcifications are usually found in the root canal and less often in coronal area  These calcification surrounds blood vessels  These calcifications may be classified as dystrophic calcification

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Diffuse calcification

Diffuse calcification of the pulp, seen along with pulp fibrosis www.rxdentistry.blogspot.com

Dystrophic Mineralization Ground substance alterations in the dental pulps occurs on aging, such charges may contribute to cellular degeneration and increase dystrophic mineralization. Circulatory disturbances may be the initiating factor Mineralizations also seen in the myelin sheaths of nerves.

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Their beginnings are also found in the vessel walls as in arteriosclerosis. Older, fibrotic pulp attract mineral salts more readily. A mineralized pulp when extirpated, feels wooden hard.

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Dystropic mineralization due to caries and periodontal disease DM also increase as result of disease processes such as caries and periodontal diseases Teeth whose pulps one chronically inflammed contain DM in regions of previous liquefaction necrosis.

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Alkaline phosphate in odontoblasts may function as a calcium pyso phosphatus, there by stimulating ca2 uptuke in pulps. Teeth with periodontal disease, DM increase in both cornonal and radicular pulp.

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AGE CHANGES • Formation of secondary dentin through out life, reduces the size of the pulp chamber and root canals • Decrease in cellularity • Odontoblast decrease in size & number, & may disappear in certain areas. Especially on pulpal floor over bifurcation & trifurca

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• Increase in number & thickness in collagen fibers particularly radicular pulp • Reduction in the nerve fibers & blood vessels • Increase resistance of pulp against action of enzymes • In dentin, Increase in peritulular dentin Dentinal sclerosis, reduces permeability Increase in dead tracts www.rxdentistry.blogspot.com

Factors infulencing Tertiary Dentinogenesis Reactionary Dentinogenesis: • Shallow cavity- RDT > 0.5mmRD • Deep cavity - RDT 0.25mm - RD • Very deep cavity- RDT 0.008 –0.25mm RD Reparative Dentinogenesis: • Pulp exposure – RDT< 0.008mm- Reparative dentin formation. www.rxdentistry.blogspot.com

Tertiary Dentinogenesis

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CLINICAL CONSIDERATIONS 1. Anatomic considerations 2. Factors to be considered during endodontic treatment. 3. Effect of Operative Procedures 4. Effect of dental materials on pulp 5. Effects subsequent to restoration

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ANATOMIC CONSIDERATIONS

Pulp Chamber withwww.rxdentistry.blogspot.com stone Cervical horns

OPERATIVE PROCEDURES Anatomic considerations 2) Shape of the pulp chamber and its extensions into the cusps pulpal horns is important. 3) Wide pulp chamber into tooth of young person will make a deep cavity preparation hazardous www.rxdentistry.blogspot.com

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

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FACTORS TO BE CONSIDERED DURING ENTODONTIC TREATMENT

5) Age advance , the pulp chamber becomes smaller difficult to locate the root canals. 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 roentgenograms.

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FACTORS TO BE CONSIDERED DURING OPERATIVE PROCEDURES 8) The pulp is highly responsive to stimuli, even slight stimulus cause inflammatory cell infiltration. 9) Dehydration causes pulpal damage operative procedures producing this condition should be avoided.

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 Filling material contain harm ful chemicals Silicate cement - acid Composites - monomer  Vital pulp is essential to good dentition. Now vital tooth becomes brittle and is subject to fracture.

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EFFECT OF DENTAL MATERIALS ON PULP GIC – Well tolerated by pulp Calcium hydroxide – includes dentin bridge formation. Zine oxide – eugenol- has an anti-bacterial effect. Formocresol – Cause chronic inflammation of the pulp. Dentin bonding agent – can irritate the pulp causing inflammation www.rxdentistry.blogspot.com

DETECTION OF PULP VITALITY Electric pulp testing More accurate than some of the tests used to detamine pulp vitality Heat testing Thermal testing Cold Anesthetic testing www.rxdentistry.blogspot.com

Anesthetic testing Test cavity This test performed when other methods of diagnosis have failed The test cavity is made drilling through enamel – dentin junction of an unanaesthetized tooth  Pulse oximeter Based on evaluating oxygen saturation of the tissue. www.rxdentistry.blogspot.com

CONCUSION • THE PRESEVATION OF A HEALTHY PULP DURING OPERATIVE PROCEDURES AND SUCCESSFUL MANAGEMENT IN CASES OF DISEASES ARE TWO OF MOST IMPORTANT CHALLENGE TO THE CLINICAL DENTIST. www.rxdentistry.blogspot.com

REFERENCES  DENTAL PULP; Seltzer & bender;  ORAL HISTOLOGY AND EMBROLOGY; Orban  ORAL HISTOLOGY; Tencate  PATHWAYS OF THE PULP; Cohen  ENDODONTIC PRACTICE; Grossman  ENDODONTICS;Ingle  ENDODONTIC PRACTICE;Weine

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