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  1. 1. PULP Introduction The dental pulp has its genesis in the 6th week of 10 life during initiation of tooth development. It forms from cranial neural crest derived ectomesenchymal cells which have migrated cephalically over the developing fore brain and ventrally around the developing foregut. These cells migrate extensively. Some travel down the sides of the head into the maxilla and mandible. During tooth formation aggregates of the neural crest cells, form the individual dental papilla which eventually become dental pulp. Thus the papilla is the primordium of the pulp after dentinal forms it is called keep. Histogenesis continues and cells differentiate into odontoblasts and pulp. This process is due to embryonic induction and epithelial, mesenchymal interaction. Both these processes need cell to cell communication in the form of: 1. Cytoplasmic process and gap junction. 2. Synthesis, release and diffusion of information molecules. 3. Information contained within cells derived, membrane delimited matrix vesicles being shuttled between the tissues. 1
  2. 2. Originally the pulp is large. It later attains normal dimension due to pulpal migration and due to dentinal apposition. In the bell stage of tooth development the blood vessels become established in the papilla. There are 52 pulp organs seen 20 seen are primary and 32 permanent. Total volume is primary – 2°C .2 CC – 38°C .38 CC Common features of pulps of all teeth are pulp chamber. Pulp can be divided into – Coronal pulp – Radicular pulp – Accessory canals – Apical foramen Coronal pulp Centrally situated shows 6 surfaces Roof or the occlusal portion Mesial surface Distal surface Buccal surface Lingual surface Where the coronal pulp becomes the radicular pulp a cervical constriction is seen. 2
  3. 3. The pulp horns or cornua are protrusions that extend into the cusps of each crown. Radicular pulp Anterior teeth have a single root canal and posteriors have multiple where it is widest. This is continuous with a PA connective tissue through the apical foramen. The shape of the radicular pulp is tubular or funnel shaped. An inferior projection of the coronal connective tissue extending from cervix to apex. The caliber of the canal is greatest during development and decreases as life increases. Root walls may be interrupted by accessory canals / channels, lateral canals, sec canals, apical ramifications. Apical foramen Average size – Maxillary – 4mm Mandibular – 3mm Location may change because of the various physiological factors like mesial migration and tipping which will cause the apex to tilt. This can be explained as follows: Pressure on one wall will cause resorbtion of that wall but at the same time deposition may be seen on the opposing wall. May be lateral in position or it may branch at the tip to form 2 foramina. 3
  4. 4. Accessory canals May be seen any where from floor along the length of root. Most commonly seen in: acpical are third 1. When the dentin is forming it might encounter a blood vessel and therefore hard tissue will form around it. 2. Premature loss of root sheath cells because these cells will induce formation of odontoblasts. 3. some times in molars they may pierce through the intra radicular fork of the tooth and enlarge from the floor of the pulp chamber. Cross description of pulps of maxillary and mandibular teeth MX CI Showel shaped coronally with 3 short borns on the coronal roof tapering down to a triangle root in cross section with the patient of triangle pointing lingually. Small spoon shaped round root at apex. Cuspid – longest with an elliptical cross section. Large occlusal cervical pulp with a mesial concavity on the cervical 1/3rd of chamber devides into 2 funnel shaped roots similar but with only root. Roughly rectangular cervical cross section with the greatest dimension buccolingually and also demonstrating mesiobuccal prominence. 3 roots 4
  5. 5. lingual is longest DB is shortest from the 1st molar to 3rd crowns get smaller and roots closer. MN CI – smallest pulp and is long and narrow with a flattened elliptical shape in C.S. LI – It is the smallest. C – Similar to but shorter than the maxillary canine. 1PM – Similar to the canine 2PM – Lingual horn is much smaller than the buccal horn. M – Coronal cross section is rectangular mesiobuccal horn is highest distolingual is lowest. Structure of the pulp Pulp is a specialized loose connective tissue – Structurally this character implies that this tissue contains more cells and amorphous ground subs/unit area than it does fibres. The pulp shows 4 distinct zones: 1) The odontoblastic zone. 2) Subodontoblastic cell free zone of weil (which is not really cell free). 3) The cell rich zone. 4) Core of the pulp 5
  6. 6. Cell free zone This is a space in which the odontoblasts may move pulpward during tooth development and lateral to a limited extent in furcationing teeth. This zone is inconspicuous during early stages of rapid dentinogenesis as odontoblast migration is greatest at that time. This zone is most well defined in coronal pulp and its thickness is around 40µm. This zone is only cell free in haemotoxylin and eosin sections. When special nerve stains are employed an extensive unmyelinated nerve plexus is seen called the: Subodontoblastic Nerve Plexus From this plexus nerves emanate and arbourize on the odontoblasts (and their processes). They also pass between the cells to eventually terminate within the dentinal tubules. The cell free and cell rich zone both, are formed rather late in the histogenesis of the pulp mostly after eruption. Components of this zone are mostly ground subs. In which are seen reticular argyrophylic fibres. Apart from this some pericytes may be located in the capillary plexus:  Fibroblasts may be present to maintain and or produce fibrils.  Macrophages.  Cellular components of blood and lymphatic channels. 6
  7. 7. Cell rich zone This zone is more deeply situated pulpward. Seen in both coronal and radicular pulp. This zone contains: 1) Fibroblasts 2) Undifferentiated ectomesenchymal cells. 3) A rich capillary plexus. These include: 1) Ground substance or intercellular matrix. 2) Fibres. 3) Cells - Fibroblasts. - Undifferentiated mesenchymal - Odontoblasts - Macrophages. Ground substance or the inter cellular matrix is abundant in young pulps. It is gelatinous in consistency and dense. Its appearance varies from finely granular to fibrillar and appears more dense in some areas with some clear spaces left between various aggregates. The nature varies depending upon the qualitative aspect of its fibre component. Composition – consists of - Acid mucopolysaccharides. 7
  8. 8. - Protein polysaccharides compounds. Glycosamino glycans Proteoglycans  During early development the presence of - Chondroitin A & B And hyaluronic acid has been demonstrated in abundance.  The ground substance lends support to the cells of the pulp.  It also serves as a means of transport of metabolites and nutrients from cells to blood vessels as it is a highly diffusible medium. Fibres  The fibres in the pulp include: - Reticular / precollagen - Collagenous - Oxytalan / preelastic - Elastic  The fibres change from development or stages to advanced age, collagen fibres are very common most evidence states that Type I is more common but recent studies have stated that both Type I and III collagen fibres may be seen which are genetically different.  The collagen fibres in the pulp are found throughout the pulp mostly in apical region. In H & E stained sections they may be pink but with silver stains are used they exhibit argyrophilia i.e. they appear dark brown to black. These are the precollagenous fibers. 8
  9. 9. These form a delicate network pursuing spiral or straight path. Electron microscopy shows that fibrils exhibit typical 64nm cross striations. The large collagen fibrils vary from 10-100µm in large. In very young pulp fibres ranging from 10-12nm are seen. Their significant is unknown. After root completion the pulp matures and bundles of collagen fibres increase in number. They may be scattered throughout the root or they may be in bundles especially in apical portion. These are termed as diffuse or bundle collagen depending on appearance. Their presence may be related eminence mental trauma. The fiber bendles are most prevalent in the root canals especially near the apical region. Cells of the pulp The pulp is composed of 4 major cell type 1. Odonto blasts 2. Un differentiated mesencymeal cells. 3. Fibro blasts 4. Cells like histiocytes / macro phage 9
  10. 10. - Plasma Cells - Most cells The first 3 cell types are permanent resident of the dental pulp. 1. Odontoblasts these are the largest and the second most prominent cell of the pulp the first being the fabroblast. They are seen adjacent to the predentin with the cell bodies in pulp and process in dentin. Size 5-7 µm in diameter, 25 – 40 µm in length Cell bodies Columnar with large oral nuclei. These fill the basal part of the cell. Immediately adjacent to the nucleus is the rough endo plastic reticulum and the gogli apparatus. The cells lie every close to each other and the plasma membranes exhibit junctional complexes. Towards the apex of the cell appears rough endo plasmic reticulum. Near the pulpal pre dentinal junction there are no cell organells. The clear terminal part of the cell body and the adjacent inter cellular junction is described by some as the terminal bar apparatus of the odontoblasts. At this zone the cell consists to a diameter of 3-4 mm where the cell process enters the predental tubule. 10
  11. 11. The process contains no active dentinogenesis it shows certain mito chondria and vesicles. Efferent motor pathway Has symphathetic fibres these enter through apicals foramen in the turnica adventitia of arterioles, they travel with the vessels end in turnica media of arterioles and their branches and capillaries. These provide vasomotor control to circulation and regulates blood flow. An interesting point is the role of nerve fibres in dentinogenesis. According to Ingle, Avery and colleagues reported that both parasymptamathetic and sympathetic nerves innervate odontoblasts. Only the nerves in the inferior alveolar nerve trunk influence odontoblastic function. When this nerve is sectioned and a cavity prepared in dentin the odontoblasts react and form sec dentin throughout the pulp rather than just below the cavity. So inferior alveolar nerve may contain parasymptomatically motor nerves that regulate the rate of dentinogenesis. Sympathetic nerves may also play a role in regulating the eruption as follows. They regulate blood flow by opening / closing AV shunts this may secondarily affect eruptive pressure. During the early active phase of dentogenesis  The golgi apparatus is more prominent. 11
  12. 12.  The rough endoplasmic reticules is more abundant.  Numerous mitochondria are seen throughout the odontoblast.  Peripherally many vesicles are seen where there is evidence of protein synthesis along the tubule wall the cell actually increase in size as its process lengthens when the process becomes 2mm long it then many times greater in volume than the allbody. The odontoblasts may differ in shape throughout the pulp. Tall columnar coronal pulp Cuboidal in middle of the root. Spindle shaped and ovoid – in apex Therefore here they resemble osteocytes, the processes being the only differentiation. Irregularly in near apical foramen appearance. Derived from the cranial neural crest cells. 2) Fibroblasts 3) Undifferentiated mesenchymal cells These cells are seen primarily in the young pulp throughout the pulp the mature pulp also contains a relatively large population. These cells are seen in – cell rich zone, pulp tissue proper. They are characterized by – undifferentiated uncommitted appearance. Under electron microscope they appear large, polyhedral cells. With a large lightly staining centrally placed nuclear. 12
  13. 13. They have abundant cytoplasm and peripheral cytoplasmic extensions. Nuclear contains heterochromatin cytoplasm is rich in free ribosomes and poly ribosomes. Microtubules and microfilaments are present which allow the cell to wander this wandering movement is via Fibroblasts The fibroblasts are seen in greatest no. in the pulp. Numerous in coronal portion where the cell rich zone is seen. In the central pulp or core it is most prevalent. They are derived from undifferentiated M. cells. They exist in 2 states Active fibroblasts Inactive fibrocytes. They are stellate cells with processes which join other They show Elliptical centrally placed nuclear which resides within a mass of homogenous cytoplasm. Cytoplasm shows extensive rough endoplasmic reticulum, golgi complex microfilaments periapical pinocytic vesicles which are the characteristic of a protein synthesing cell. In old pulp these cells appear rounded or spindle shaped with short processes, decreased cell organells and less cytoplasm these cells are called fibrocytes. 13
  14. 14. The fibrocytes are believed by some to be precursors of fibroclasts i.e. when activated they turn into fibroblasts because these 2 are different states of the same cell and this cell and this cell can rapidly associate between these cells depending on status of surrounding connective tissue. A third state has been discussed of the fibroblast i.e. the fibroblast. This is the collagen resorbing cell seem more commonly in the periodontal ligament as turn over of collagen is more here. But according to Walter Davis et al it is most likely to be present in pulp as it also shows turn over of collagen. Functions of fibroblasts 1. Form and maintain the pulp matrix i.e. collagen and ground substance. 2. They may also ingest and degrade the collagen when appropriately stimulated. They are transient cells which wander in and out of the cell depending on the status of the tissue. Macrophages – take their origin from the specific circulation W.B.C’s, the monocytes which themselves are relieved from precursor cells in bone marrow. Under light microscope they appear as pleomorphic cells with an eccentrically placed indented or kidney shaped nuclear. Cytoplasm frequently shows foamy / bubbly appearance due to presence of a vascular system of lysosomes. The peripheral boundaries are usually quite difficult to ascertain because of numerous cell processes or pseudopodia. 14
  15. 15. Under transmission electron microscopy the following characteristics are seen: 1. A surface with numerous pleates and protrusions indicative of their phagocytic activity. 2. An extensive vacuolar and lysosomal system for the intracellular digestion of engulfed materials such as bacteria. 3. Well developed rough endoplasmic reticulum. 4. Numerous microfilaments and microtubules which function in cell migration and phagocytosis. The primary function of macrophages is the ingestion and subsequent digestion of particulate materials. This process involves: - Pinocytosis - Phagocytosis Acid hydrolytic enzymes formed in lysosomes. It also participates in immune response in fact it may activate the immune response. Cell mediated resistance to infection When stimulated by foreign materials they undergo an activation process involving an increase in phagocytosis and an elevation in lysosomal enzyme activity. Such cells are called activated macrophages. 15
  16. 16. Other cells Mast cells, plasma cells seen during inflammation. Lymphocytes and eosinophils are seen and they increase during inflammation. - BLOOD supply and VESSELS - Blood supply of the pulp and Periodontium Inferior/Superior alveolar artery and veins in the mandibular and maxillary regions respectively. The blood vessels enter and exit the pulp through the apical and accessory foramina. Their structure here changes and their walls become thinner. After entering the radicular pulp the vessels course in an almost straight line towards the coronal pulp. As the vessels course coronally some lateral branching is apparent. In the coronal region they arbourize into an extensive capillary plexus the sub odontoblatic capillary plexus. These plexus is seen in the cell rich and cell free zone and is responsible for nurturing the proximal odontoblastic processes. 16
  17. 17. Structures – 3 layers are seen: 1. Tunica intima. 2. Tunica media 3. Tunica adventitia Tunica intima is the innermost layer contains – squamous cells surrounded by closely associated basal lamina. Tunica media - 5µm thick and contains 1-3 layers of smooth muscle cells. Between these 2 layers there is a basal lamina which separates them. Where the endothelial cell wall contacts the muscle cells it is called myoendothelial junction. Tunica adventitia – is madeup of few collagen fibres forming a loose network around the larger arteries this layer becomes more contagious in older pulp. This layer blends with the fibres of the surrounding inter cellular tissue. Few terminal arterioles with very small diameter appear peripherally in the pulp which contain many micropinocytic vesicles which function in transendothelial movement, the basal lamina may serve as a molecular sieve and regulate flow of materials into pulp. Some capillaries passes fenestration about 60nm in diameter at these sites the internal and external cell membrane comes into close proximity therefore facilitate the exchange of material. 17
  18. 18. Blood flow Blood flow in the pulp is more rapid than any other tissue as the pressure is higher than any other in the body. Arterioles – .3-1mm/sec Venules – .15mm/sec Capillaries – C .08mm/sec The largest arteries in pulp are 50-100µm in diameter equal to the arterioles found in other places in the body. Arteriovenous anastomoses are vessels which directly connect arteries with veins and thus shunt and bypass the capillary network. In the roots shunts are much smaller than the crown of all the areas of the pulp most vascularized is the periphery where the dentinogenic cells are present. Some unique blood vessels 1) In a study conducted by Reizo Inoki et al some teeth were viewed with the terminal capillary network removed. 2 or 3 main venules form an arch like with larger vessels in distal and mesial root. So, the venules from central and mesial pulp horn advance towards the mesial canal and vice versa between which we can seen an arteriovenous anastomosis. This distinguishing feature suggests that this area represents a demarcation of blood flow from both sides. 2) Another feature is the U turn loop located in root canal pulp. 18
  19. 19. A main arteriole forms the loop and 2/3 fine branches are given out the narrowing at the branching point suggests the presence of a sphincter. Therefore this loop may play a role in blood flow regulation. 19
  20. 20. Some special characteristics of pulpal circulation - Heterogenous flow. - Peripheral layer 4 time of centre. - Coronal tip – highest. - Coronal area twice of root area. - Shunting - 41% in apical ½ - 25% in cornal ¼. Lymphatics of the pulp As a result of conflicting observations much uncertainty persists regarding the presence or absence of a pulpal lymphatic system. Most of the evidence favouring the presence of lymph vessels in the pulp is derived from the trace tests and other special techniques involving perfusion, topical application and injection of foreign material. Lymph channels are identified morphologically by their large lumen of irregular contour. Their endothelial lining is composed of squamoid cells whose continuity is interrupted by gaps between cell junctions. Intimal lining is bordered by discontinuous muscle fibres. A basal lamina does not separate the endothelium and the media. The vessels empty into the arterior submental lymphnodes and the post submandibular and deep cervical lymphnodes. 20
  21. 21. Nerves Composed of sensory afferent and autonomic afferent systems. Sensorer afferent impulses start from unmyelinated N endings to cortex of brain here interpreted as pair. Efferent system from CNS to Smooth muscles of arteries they regulate the volume and rate of blood flow thus they central the intrapulpal BP and dentin formation. Generally N fibres are classfied into A and C α β σ γ 80% are C type fibres gpiu, 20% AS / 9P III ‘C’ are the ones carrying pain itch temperature and crude touch sensation diameter D-03 – 1.2 µm Conduction velocity is 04 – 2m/sec. This is very slow. According to F.S. Weine and associates these are distributed throughout the pulp therefore they conduct throbbing and aching pain associated to pulp damage. ‘Au’ s/delta – in general carry temperature crude touch and prior pain sensation. *myelinated *D-2-5 µm C. vel- 6-30m/sec this is a higher velocity therefore these impulses are interpreted as sharp pricking pain. 21
  22. 22. Distributed in the odontoblastic and subodontoblastic zone and are associated with dentinal pain. Some of the nerve bundles advance towards the cell rich zone bench and pursue circuitous routes forming a dense network pulpward to the cell free and cell rich zones they are called Rashkow plexus / parietal nerve plexus majority of fibres are of small diameter. Most of these fibres do not terminate in the subodontoblastic plexus continue onloose their myelin sheath pass between the odontoblasts terminate on cell series of odontoblasts. Others terminate on the odontoblast process and some may also go till the dentino enamel junction. At the apical foramen unmyelinated symphathetic nerve fibres also enter the pulp. Sensory response in the pulp cannot differentiate between heat touch pressure or chemicals because the pulp organs lack, the type of receptors that specifically distinguish those stimuli. Functions of the pulp  Inductive  Formative  Nutritive  Protective  Defensive 22
  23. 23. Inductive – cells produce the dentin that surrounds and protects the pulp. The pulp odontoblasts develop the organic matrix and function in its calcification. The pulp also induces the enamel organ to become a particular type of tooth. Formative – The pulp organ cells produce the dentin that surrounds and protects the pulp. The odontoblasts develop the organic matrix and function in its calcification. Through the development of the odontoblast proceses dentin is formed along the tubule wall as well as at the pulp perdentin front. Nutritive – The pulp nourishes the dentin throught the odontoblasts and their processes. Dentin is formed along the tubule wall as well as at the pulpal pre dentin front. Protective – The sensory nerves in the tooth respond with pain to all stimuli such as heat cold pressure operative cultive procedures and chemicals. The nerves also initial reflexes that central circulation in the pulp this sympathetic function is a reflex providing stimulation to visceral motor fibres terminating on the muscles of blood vessels. Defensive – the pulp is an organ with remarkable restorative abilities. It responds to irritation whether mechanical, thermal chemical or bacterial by producing reparative dentin and mineralizing any affected dentinal tubules. Both, reparative dentin created in the pulp and the calcification of the tubules (sclerosis) are attempts to wall off the pulp from source of irritation. Age changes The pulp and the dentin are 2 components of a single entity called the dentin pulp complex. 23
  24. 24. As a result of this arrangement many of the age changes that affect one tissue consequently affect the other. Recession of pulp Recession Pulp recession results from the formation of secondary dentin. The pulp has its full volume and shape only when the tooth is completely erupted. After 20 yrs of age the secondary dentin deposition starts. In old teeth the root canal is often not more than a thin channel and may also be obliterated in some cases. This continued restriction in pulp volume brings about a reduction in vascular supply and initiates many of the other changes. Changes are seen in all the cells of the pulp ground substances fibres, cells, vascular and lymphnodes channels and nerve. Ground substance - Diminishes with age. - Amount of glucosamino glycans and glycopeptides decreases. Cells – are fewer smaller in old pulp characterized by decrease in the size and number of cytoplasmic organells. The fibroblast in the aging pulp exhibit less perinuclear cytoplasm and posses long thin cytoplasmic processes. The intracellular organelles are reduced in number and size. Fibres – As a definitive stage of pulp organ is acquired only collagen type I is present these increase in number and organization with ageing of the tissue. 24
  25. 25. According to tencate the above mentioned fact may not be so true as some recent investigations have proved that there is no significant change in collagen content. In the absence of disease the stabilization of collagen content occurs as a result of finished collagen synthesis and a lowered rate of collagen degradation. A true age change is the occurrence of calcifications in the pulp. Pulp stones These are nodular calcified masses appearing in coronal or root portions of pulp. They are classified according to their structure as: - True denticles. - False denticles. - Diffuse calcifications. True denticles, are rarely seen and are usually located close to the apical foramen. Development may be due to inclusion of remnants of the epithelial root sheaths within the pulp. These induce the pulp to differentiate into odontoblasts which then form the dentin masses called true pulp stones. Their structure is similar to dentin i.e. they exhibit dental tubule containing the processes of odontoblasts that formed them. False denticles appear as concentric layers of calcified tissue. In some cases these calcification sites appear within a bundle of collagen fibres. 25
  26. 26. Other times they appear in a location in the pulp free of collagen. Some arise around b vessels. 1. Formation – remnants of necrotic and calcified cells may act as nidi for false denticles. 2. Phleboliths – calcification of thrombi in blood vessels. All dentincles begin as very small but layer increase in size as increcentral growth takes place on their surface. Diffuse Calcifications These appear as irregular calcific deposits in the pulp tissue may appear as large masses or as fine calficied spicules these are more commonly seen in the root canal. Particles are more in the coronal pulp. Another classification for the pulp stones may be based on their position in relation to the dentinal wall. Free attached embedded free are surrounded by pulp tissue. Attached are attached to dentinal wall embedded are embedded in dentin. Clinical significance The dental pulp a clinical view point a highly specialized connective tissue organ presenting many unique considerations. Main ones are those associated with its normal morphologic variation and its low compliance environment. 26
  27. 27. Deviations in both morphologic and environmental pulpal states may be initiated or influenced by traumatic episodes such as a blow to the tooth, caries or periodontal disease. Morphologic considerations Variations in pulpal morphology should be recognized and managed for successful pulpal treatment. Accessory canals and lateral canals These canals may serve as avenues of communication between the pulp and periodontal tissues. Pathologic situations interaction may occur via toxic products and inflammatory extensions leading to pulps periodontal brakedown. During periodontal procedures like scaling and root planning the tissue in these channels may have their vasculature severed and localized tissue necrosis may occur. Apical Delta The presence of multiple accessory canals at root apex is termed as an apical delta. If necrotic tissue is not removed these channels may serve as a possible source of periapical irritation. 27
  28. 28. Branching of the main canal May occur periapically in the mid 1/3 or apical 1/3 and is evident as fast break in the radiographic dentistry of the pulp space often radiographs have to be angulated and taken to see visualize these clearly. Nastomoses, Fins, Webbing and Prolongations These terms described irregularities in the shape of the pulp tissues. They may be very fine and more problems in adequate cleansing of canals. Some combination of chemical bend mechanical debridement is needed to cleanse these canals. Calcifications These may make acces and location of canals difficult occasionally a chelating agent may be needed to aid in penetration of calcific barriers. Premature pulpal degeneration If the apical root is immaturely developmed then the apical stop may not be seen if the tooth is non vital, necrotic contents must be improved and canals be packed with an agent capable of producing a hard tissue at the apex. This bridging over of root apex with calcific bridge is called apexification. 28
  29. 29. Environmental considerations Caries – if the irritant or cause is mild then repairative dentin may be deposited. If severe then it might lead to reversible pulpitis at which shape the inflammation has not engulfed the pulp. If untreated irreversible pulpitis and subsequent necrosis of pulp may occur. Internal Resorption As a result of trauma the mesenchymal cells may undergoes a metaplastic differentiation to odontoclastic cells. This leads to dentinal resorbtion. Unless the pulp is removed the process might perforate to the external surface of the tooth. Internal resorbtion is usually asymptomatic and can be easily diagnosed on POPA radiographs. Extensive inflammatory hyperplasia of the tooth may lead to the clinical appearance of the tooth as pink where all the dentin has been resorbed and hyperplastic pulp is visible through the thin enamel. Called pink tooth of mummery odontoclastoma / internal granuloma. Restorative procedure A thorough knowledge of the pulp is needed before starting any restorative procedure. In young tooth the pulp chamber is very wide so, a deep cavity may prove hazardous especially so if pulp horns are large and high. In preparing access cavity care should be taken e.g. in old teeth chamber is very small and large access in molars may lead to furcation perforations. 29
  30. 30. Also orifices may be very narrow, so pur should always be angulated towards the largest canal to avoid furcations. Mechanical cutting of tooth structure may result in thermal changes or dentin classification further more when irritating cements are used without proper base may stimulate an occur whelming inflammatory or degenerative response. The closer a restoration is to the pulp the greater is the chance of damage. Previously it was believed that an exposed pulp is a lost pulp. But research have proved that proper pulp tipping procedures may present the pulp. This is especially true in young pulp where regenerative capacity is more. The deleterious effects of restorative procedures may be enhanced by deposition of local anaesthesia a with vasoconstrictor at root apex. Epinephrine produces a diffuse vasoconstriction of the blood vessels of the pulp and may interferes with the necessary inflammatory response to the clinical procedure so it should be avoided minor cavity cutting procedures. Pulp is essential dentition so every production should be taken to preserve the vitality of the pulp. The preservation of the health of the pulp during operative procedures and its successful engagement in cases of disease is ne of the most important challenges to the clinical dentist. 30
  31. 31. If the vitality is lost and root canal therapy is performed then the tooth becomes brittle and is subject to fracture so necessary precautions should be taken to avoid this. Conclusion The pulp is also known as an encapsular organ as it is very similar to only one other tissue in this aspect i.e. the bone marrow. Although rough knowledge of the pulp is a must for any clinician before undertaking any restorative procedures as the pulp is very sensitive tissue and may pact to the slightest of stimuli also. 31