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Textbook of Endodontics System requirement: • Windows XP or above • Power DVD player (Software) • Windows media player version or above (Software) . PDF | The current edition builds up on the platform established by the previous edition and clinical textbook for students across South Asia. 2. Book Review. Textbook of Endodontics is an inimitable textbook designed eruditely to meet the requirements of undergraduate students. The book has been.
Defence cells: It contains large vessels and nerves from which branches extend to peripheral layers. Ultrastructure of the odontoblast shows large nucleus which may contain up to four nucleoli. Please send us reviews and suggestions to incorporate in further edition of this book to make it more student friendly. This nerve proceeds coronally with afferent blood vessels and later divides into cuspal nerves at the coronal portion of the tooth. On approaching the cell free zone of pulp.
Sharp, quick and momentary pain C-fibers 1. Slow conduction velocity 0. Unmyelinated 3. Not well localized 4. Have high threshold 5. Dull throbbing The send free nerve endings into dentinal tubules. This space is called pulp cavity which is divided into pulp chamber and root canal Fig.
In the anterior teeth, the pulp chamber gradually merges into the root canal and this division becomes indistinct Fig. But in case of multirooted teeth, there is a single pulp chamber and usually two to four root canals Figs 2. As the external morphology of the tooth varies from person to person, so does the internal morphology of crown and the root.
The change in pulp cavity anatomy results from age, disease, trauma or any other irritation. The roof of pulp chamber consists of dentin covering the pulp chamber occlusally. Canal orifices are openings in the floor of pulp chamber leading into the root canals Fig. A specific stimulus such as caries leads to the formation of irritation dentin. With time, pulp chamber shows reduction in size as secondary or tertiary dentin is formed Fig.
The shape of root canal varies with size, shape, number of the roots in different teeth. A straight root canal throughout the entire length of root is uncommon. Commonly curvature is found along its length which can be gradual or sharp in nature Fig.
In most cases, numbers of root canals correspond to number of roots but a root may have more than one canal. Diagram showing pulp anatomy of anterior tooth Fig.
Diagram showing pulp cavity of posterior tooth 15 Radiographic appearance of pulp cavity According to Orban, the shape of the canal to large extent is largely determined by the shape of the root. Root canals can be round, tapering elliptical, broad, thin, etc. Change in shape and location of foramen is seen during post-eruptive phase due to functional forces tongue pressure, mesial drift acting on the tooth which leads to cementum resorption and deposition on the walls of foramen.
This whole process resulted in new foramen away from the apex. The total volume of all permanent pulp organs is 0. The apical foramen is an aperture at or near the apex of a root through which nerves and blood vessels of the pulp enter or leave the pulp cavity Fig.
Normally, it is present near the apex but sometimes, opening may be present on the accessory and lateral canals of root surface forming the accessory foramina. In young newly erupted teeth, it is wide open but as the root develops, apical foramen becomes narrower.
The inner surface of the apex becomes lined with the cementum which may extend for a short distance into the root canal. Thus we can say that dentinocemental junction does not necessarily occur at the apical end of root, but may occur within the main root canal Fig.
Multiple foramina are frequent phenomenon in multirooted teeth. Majority of single rooted teeth have single canal which terminate in a single foramina. Continuous deposition of new layers of cementum causes change in foramen anatomy. Average size of maxillary teeth is 0. Diagram showing opening of canal orifices in the pulp chamber Fig. Straight and curved root canal Fig. Reduction in size of pulp cavity because of formation of secondary and tertiary dentin 16 Fig. Diagram showing relationship between shape of root and number of root canals Pulp and Periradicular Tissue Fig.
Diagram showing accessory and lateral canals Fig. Apical foramen through which nerves and blood vessels enter or leave the pulp cavity Fig. Diagram showing variation in position of cementodentinal junction Accessory canals: They are lateral branches of the main canal that form a communication between the pulp and periodontium.
Accessory canals contain connective tissue and vessels and can be seen anywhere from furcation to apex but tend to more common in apical third and in posterior teeth Fig. In other words, more apical and farther posterior the tooth, the more likely the accessory canals will be present. Exact mechanism of their formation is not known but they occur in areas where there is premature loss of root sheath cells because these cells induce formation of odontoblasts.
They also develop where developing root encounters a blood vessel. If vessel is located in this area, where dentin is forming; hard tissue may develop around it making a lateral canal from radicular pulp. Pulp performs four basic functions i. Formation of dentin 2.
Nutrition of dentin 3. Innervation of tooth 4. Defense of tooth 1. Formation of Dentin It is primary function of pulp both in sequence and importance. Odontoblasts are differentiated from the dental papilla adjacent to the basement membrane of enamel organ which later deposits dentin. Pulp primarily helps in: Nutrition of Dentin Nutrients exchange across capillaries into the pulp interstitial fluid.
This fluid travels into the dentin through the network of tubules formed by the odontoblasts to contain their processes. Innervation of Tooth Through the nervous system, pulp transmits sensations mediated through enamel or dentin to the higher nerve centers. Pulp transmits pain, also senses temperature and touch. Teeth are supplied by the maxillary and mandibular divisions of the trigeminal V nerve.
The dental nerve divides into multiple branches as it traverses the bone. At the apical alveolar plate, the A delta and C axons enter the periodontal ligament. Then the nerves enter the apical foramina and unite to form common pulpal nerve. This nerve proceeds coronally with afferent blood vessels and later divides into cuspal nerves at the coronal portion of the tooth. On approaching the cell free zone of pulp, a mixture of myelinated and non-myelinated axons branch repeatedly forming overlapping network of nerves plexus of Raschkow.
The nerve twigs either end among the stroma of the pulp or terminate among the odontoblasts. Defense of Tooth Odontoblasts form dentin in response to injury particularly when original dentin thickness has been compromised as seen in caries, attrition, trauma or restorative procedure.
Odontoblasts also have the ability to form dentin at sites when dentin continuity has been lost. The formation of reparative dentin and sclerotic dentin are defense mechanisms of the tooth.
Textbook of Endodontics Pulp also has the ability to elicit an inflammatory and immunologic response in an attempt to neutralize or eliminate invasion of dentin by caries causing micro-organisms and their byproducts. These changes can be natural or may be result of injury such as caries, trauma or restorative dental procedure. Regardless of the cause, the pulp shows changes in appearance morphogenic and in function physiologic.
Continued deposition of intratubular dentin- reduction in tubule diameter. Reduction in pulp volume due to increase in secondary dentin deposition Fig. Presence of dystrophic calcification and pulp stones Fig. Decrease in the number of pulp cells-between 20 and 70 years. Cells density decreases by 50 percent. Degeneration and loss of myelinated and unmyelinated axons—decrease in sensitivity.
Reduction in number of blood vessels- displaying arteriosclerotic changes. Once believed that collagen content with age reduces, but recent studies prove that collagen stabilizes after completion of tooth formation.
With age, collagen forms bundle making its presence more apparent. Decrease in dentin permeability provides protected environment for pulp - reduced effect of irritants. Possibility of reduced ability of pulp to react to irritants and repair itself. The larger calcifications are called denticles. It is seen that pulp stones are present in at least 50 percent of teeth.
Pulp stones may form either due to some injury or a natural phenomenon Fig. Diagram showing true denticle Fig. Reduction in size of pulp volume Fig. Diagram showing pulp stones and reduced size of pulp cavity 18 Fig. Free, attached and embedded pulp stones Classification of pulp stone 1. According to structure a. True b. False 2. According to size a. Fine b. Diffuse 3. According to location a. Free b. Attached c. Embedded According to Structure They can be classified into true and false denticles.
The difference between two is only morphologic and not chemical. True Denticle A true denticle is made up of dentin and is lined by odontoblasts. These are rare and are usually located close to apical foramen. Development of true denticle is caused by inclusions of remnants of epithelial root sheath within the pulp Fig. False Denticles Appear as concentric layers of calcified tissue. These appear within bundles of collagen fibers. They may arise around vessels.
Calcification of thrombi in blood vessels called, phleboliths, may also serve as nidi for false denticles. All denticles begin as small nodules but increase in size by incremental growth on their surface. According to Size According to size, there are fine and diffuse mineralizations. Diffuse calcifications are also known as fibrillar or linear calcifications because of their longitudinal orientation. They are found more frequently in the root canals, but can also be present in the coronal portion of the pulp.
They are aligned closely to the blood vessels, nerves or collagen bundles. According to Location they can be Classified as: Attached denticles are partially fused dentin Fig. Embedded denticles are entirely surrounded by dentin calcifications, are seen more in older pulps.
This may be due to increase in extent of cross linking between collagen molecules. Clinical Significance of Pulp Stones Presence of pulp stones may alter the internal anatomy of the pulp cavity.
Thus, making the access opening of the tooth difficult. They may deflect or engage the tip of endodontic instrument. Since the pulp stone can originate in response to chronic irritation, the pulp chamber which appears to have diffuse and obscure outline may represent large number of irregular pulp stones which may indicate chronic irritation of the pulp.
Calcific Metamorphosis Calcific metamorphosis is defined as a pulpal response to trauma that is characterized by deposition of hard tissue within the root canal space. It has also been referred to as pulp canal obliteration. Calcific metamorphosis occurs commonly in young adults because of trauma. It is evident usually in the anterior region of the mouth and can partially or totally obliterate the canal space radiographically. The clinical picture of calcific metamorphosis has been described by Patterson and Mitchell as a tooth that is darker in hue than the adjacent teeth and exhibits a dark yellow color because of a decrease in translucency from a greater thickness of dentin under the enamel.
The radiographic appearance of calcific metamorphosis is partial or total obliteration of the pulp canal space with a normal periodontal membrane space and intact lamina dura. Complete radiographic obliteration of the root canal space, however, does not necessarily mean the absence of the pulp or canal space; in the majority of these cases there is a pulp canal space with pulpal tissue. The pulps of 20 maxillary permanent incisors were evaluated microscopically by Lundberg and Cvek.
The teeth were treated endodontically because of progressive hard tissue formation in the canal space. The tissue changes were characterized by a varied increase in collagen content and a marked decrease in the number of cells. Osteoid tissue with included cells was found adjacent to mineralized areas in the pulp, with only one pulp showing moderate lymphocytic inflammatory infiltrate because of further trauma.
They concluded that tissue changes in the pulps of teeth with calcific metamorphosis do not indicate the necessity for root canal treatment.
The mechanism of hard tissue formation during calcific metamorphosis is characterized by an osteoid tissue that is produced by the odontoblasts at the periphery of the pulp space or can be produced by undifferentiated pulpal cells that undergo differentiation as a result of the traumatic injury.
This results in a simultaneous deposition of a dentin-like tissue along the periphery of the pulp space and within the pulp space proper.
These tissues can eventually fuse with one another, producing the radiographic appearance of a root canal space that has become rapidly and completely calcified. The management of canals with calcific metamorphosis is similar to the management of pulpal spaces with any form of calcification.
Pulp and Periradicular Tissue Sometimes denticles become extremely large, almost obliterating the pulp chamber or the root canal. Pulp stones may be classified 1 according to structure 2 according to size 3 according to location. Cementum Cementum can be defined as hard, avascular connective tissue that covers the roots of the teeth Fig. It is light yellow in color and can be differentiated from enamel by its lack of luster and darker hue. It is very permeable to dyes and chemical agents, from the pulp canal and the external root surface.
Types There are two main types of root cementum 1. Acellular Primary 2. Cellular Secondary Acellular Cementum 1. Covers the cervical third of the root 2. Formed before the tooth reaches the occlusal plane. As the name indicated, it does not contain cells. Main function is anchorage. Cellular Cementum 1. Formed after the tooth reaches the occlusal plane. It contains cells. Less calcified than acellular cementum. Mainly found in apical third and interradicular region 6.
Main function is adaptation. Periodontal Ligament Periodontal ligament is a unique structure as it forms a link between the alveolar bone and the cementum.
It is continuous with the connective tissue of the gingiva and communicates with the marrow spaces through vascular channels in the bone. Periodontal ligament houses the fibers, cells and other structural elements like blood vessels and nerves. The periodontal ligament comprises of the following components I. Periodontal fibers II.
Cells III. Blood vessels IV. Nerves Periodontal Fibers The most important component of periodontal ligament is principal fibers. These fibers are composed mainly of collagen type I while reticular fibers are collagen type III. The principal fibers are present in six arrangements Fig. Horizontal Group These fibers are arranged horizontally emerging form the alveolar bone and attached to the root cementum.
Alveolar Crest Group These fibers arise from the alveolar crest in fan like manner and attach to the root cementum. These fibers prevent the extrusion of the tooth. Oblique Fibers These fibers make the largest group in the periodontal ligament. They extend from cementum to bone obliquely.
They bear the occlusal forces and transmit them to alveolar bone. Diagram showing periradicular tissue 20 Fig. Principal fibers of periodontal ligament Pulp and Periradicular Tissue Transeptal Fibers These fibers run from the cementum of one tooth to the cementum of another tooth crossing over the alveolar crest.
Apical Fibers These fibers are present around the root apex. Interradicular Fibers Present in furcation areas of multirooted teeth. Apart from the principal fibers, oxytalan and elastic fibers are also present. Cells The cells present in periodontal ligament are a. Fibroblast b. Macrophages c. Mast cells d. Neutrophils e. Lymphocytes f. Plasma cells g. Epithelial cells rests of Mallassez. Nerve Fibers The nerve fibers present in periodontal ligament, is either of myelinated or non-myelinated type.
Blood Vessels The periodontal ligament receives blood supply form the gingival, alveolar and apical vessels. Functions Supportive Tooth is supported and suspended in alveolar socket with the help of periodontal ligament. Nutritive Periodontal ligament has very rich blood supply. So, it supplies nutrients to adjoining structures such as cementum, bone and gingiva by way of blood vessels.
It also provides lymphatic drainage. Protective These fibers perform the function of protection absorbing the occlusal forces and transmitting to the underlying alveolar bone. Formative The cells of PDL help in formation of surrounding structures such as alveolar bone and cementum. Resorptive The resorptive function is also accomplished with the cells like osteoclasts, cementoclasts and fibroblasts provided by periodontal ligament. Radiographic appearance of alveolar bone Alveolar Bone Fig. Cells Cells present in bone are: Osteocytes b.
Osteoblasts c. Osteoclasts Intercellular Matrix Bone consists of two third inorganic matter and one third organic matter. Inorganic matter is composed mainly of minerals calcium and phosphate along with hydroxyl apatite, carbonate, citrate etc.
Bone consists of two plates of compact bone separated by spongy bone in between. In some area there is no spongy bone. The spaces between trabeculae of spongy bone are filled with marrow which consists of hemopoietic tissue in early life and fatty tissue later in life. Bone is a dynamic tissue continuously forming and resorbing in response to functional needs.
Both local as well as hormonal factors play an important role in metabolism of bone. In healthy conditions the crest of alveolar bone lies approximately mm apical to the cementoenamel junction but it comes to lie more apically in periodontal diseases.
In periapical diseases, it gets resorbed easily. Write short notes on: Zones of dental pulp b. Odontoblasts c. Accessory and lateral canals d. Innervation of pulp e. Functions of pulp f. Age changes in the pulp g. Bernick S. Differences in nerve distribution between erupted and non-erupted human teeth. J Dent Res ; Byers MR. The development of sensory innervations in dentine.
J Comp Neurol ; Heverass KJ. Pulpal, microvascular, and tissue pressure. Johnsen DC. Innervations of teeth: Kim S. Regulation of pulpal blood flow. Linde A. The extracellular matrix of the dental pulp and dentin. Dentin-predentin complex and its permeability: The characteristics of intradental sensory units and their responses to stimulation. Olgart LM. The role of local factors in dentin and pulp in intradental pain mechanisms. Pashley DH. Physiologic overview. Ruch JV. Odontoblast differentiation and the formation of odontoblas layer.
Thomas HF. The dentin-predentin complex and its permeability; anatomical overview. Veis A. The role of dental pulp—thoughts on the session on pulp repair processes. Yamamura T.
Differentiation of pulpal cells and inductive influences of various matrices with reference to pulpal wound healing. It is the principle source of pain within the mouth and also a major site of attention in endodontics and restorative treatment. Some important features of pulp are as follows Fig.
Therefore once exposed, it is extremely sensitive to contact and to temperature but this pain does not last for more than seconds after the stimulus removed. Correlation of clinical signs and symptoms with corresponding specific histological picture is often difficult. Thus the knowledge to pulp is essential not only for providing dental treatment, but also to know the rationale behind the treatment provided. Etiology of pulpal diseases can be broadly classified into: Chemical Textbook of Endodontics 3.
Bacterial 4. Radiation II. WEIN classifies the causes of pulpal inflammation, necrosis or dystrophy in a logical sequence beginning with the most frequent irritant, microorganisms.
Bacterial Bacterial irritants: In , WD Miller said that bacteria are a possible cause of pulpal inflammation Fig. Most common cause for pulpal injury-bacteria or their products may enter pulp through a break in dentin either from: Bacteria most often recovered from infected vital pulps are: Iatrogenic Pulp inflammation for which the dentists own procedures are responsible is designated as Dentistogenic pulpitis.
Various iatrogenic causes of pulpal damage can be: Thermal changes generated by cutting procedures, during restorative procedures, bleaching of enamel, electrosurgical procedures, laser beam, etc. Orthodontic movement c. Periodontal curettage d. Periapical curettage A use of chemicals like temporary and permanent fillings, liners and bases and use of cavity desiccants such as alcohol.
Idiopathic a. Aging b. Resorption internal or external Fig. Radiograph showing carious exposure of pulp in first molar Fig. Relation of pulp with its surrounding structures Fig. Formation of irritation dentin 24 Fig. Tooth decay causing pulpal inflammation Degree of inflammation is proportional to intensity and severity of tissue damage. For example, slight irritation like incipient caries or shallow tooth preparation cause little or no pulpal inflammation, whereas extensive operative procedures may lead to severe pulpal inflammation.
Depending on condition of pulp, severity and duration of irritant, host response, pulp may respond from mild inflammation to pulp necrosis Fig. These changes may not be accompanied by pain and thus may proceed unnoticed. The pulp cells exposed to ionizing radiation may become necrotic, there may occur vascular damage and the interference in mitosis of cells. Irradiations also affect the salivary glands causing decreased salivary flow, thereby increased disposition to dental caries and pulp involvement.
Radiation damage to teeth depends on dose, source, type of radiation, exposure factor and stage of tooth development at the time of irradiation. Pulpal reaction to microbial irritation Fig. Resorption of tooth involving pulp Fig. Response of pulp to various irritants 25 Gradual response of pulp to microbial invasion Degree and nature of inflammatory response caused by microbial irritants depends upon 1.
Host resistance 2. Virulence of microorganisms 3. Duration of the agent 4. Lymph drainage 5. Amount of circulation in the affected area 6. Visual and tactile inspection — 3Cs — i. Color ii. Contour iii.
Consistency 2. Thermal tests i. Heat tests — isolation of tooth — use of: Cold tests: Electrical pulp testing 4. Radiographs 5. Anesthetic tests 6. The prevalence of dental fear and avoidance expanded adult and recent adolescent surveys. Skillen WG. You should not chew or bite on the treated tooth until you have had it restored by your dentist. Often when this occurs. The one-appointment endodontic technique. The unrestored tooth is susceptible to fracture.
In a few cases. J Am Dent Assoc A few practical observations on the treatment of the pulp. J Brit Dent Assoc It continues to receive the nutrition and remains healthy.
Wolch I. Newer researches. Since introduction of rotary instruments and other technologies reduce the treatment time. What is scope of endodontics? One-appointment endodontic therapy: A nationwide survey of endodontists. Most endodontically treated teeth last as long as other natural teeth.
Br Dent J Calhoun RL. Balkwill FH. Morphology of root canals. But sometimes when root canals are not accessible. J Can Dent Assoc Landers RR. Can All Teeth be Treated Endodontically? Most of the teeth can be treated endodontically.
J Endod On the treatment of pulpless teeth. In the modern world single visit endodontics is becoming quite popular. Comparative study of the single visit and multiple visit endodontic procedure. Soltanoff W. Gatchel RJ. It has been shown that success of endodontic therapy depends on the quality of root canal treatment and not the number of visits.
Complex because of innervation of the odontoblast processes which produces a high level of sensitivity to thermal and chemical change. Due to presence of the specialized cells. The injury to pulp may cause discomfort and the disease. The innervation of pulp tissue is both simple and complex.
Secondary dentin is gradually deposited as a physiological process which reduces the blood supply and therefore. Pulp is surrounded by rigid walls and so is unable to expand in response to injury as a part of the inflammatory process.
Pulp is actually a microcirculatory system consists of arterioles and venules as the largest vascular component. Simple in that there are only free nerve endings and consequently the pulp lacks proprioception. In this chapter.
It consists of specialized cells. There is minimal collateral blood supply to pulp tissue which reduces its capacity for repair following injury. Dental pulp is identified when these cells mature and dentin is formed. Features of pulp which distinguish it from tissue found elsewhere in the body: The pulp is connective tissue system composed of cells.
Due to lack of true collateral circulation pulp is dependent upon few arterioles entering through the foramen. This enables the vital pulp to partially compensate for loss of enamel or dentin occurring with age. The pulp is composed almost entirely of simple connective tissue. Because the symptoms as well as radiographic and clinical signs of pulp diseases are not always differentiated from sign and symptoms of other dental diseases.
At the same time as tooth develops unmyelinated sensory nerves and autonomic nerves grow into pulpal tissue.
Basically the development of tooth is divided into bud. The dental papilla has high cell density and the rich vascular supply as a result of proliferation of cells within it.
Cell free zone of Weil c. Series of blood vessels arise from the plexus. Cell rich zone d. Development of tooth showing bud stage Fig. As the cells of loop proliferate. It Fig. The cap stage Fig. Textbook of Endodontics 8 Before knowing the development of pulp we should understand the development of the tooth.
The bud stage Fig. Pulp core A.
Myelinated fibers develop and mature at a slower rate. The boundary between inner enamel epithelium and odontoblast form the future dentinoenamel junction.
As the crown formation with enamel and dentin deposition continues. Zones of pulp. According to Saunders and Cutright The cells of dental papilla appear as undifferentiated mesenchymal cells.
It shows outer and inner enamel epithelia and stellate reticulum. Odontoblastic layer: Odontoblasts consists of cell bodies and cytoplasmic processes. The differentiation of epithelial and mesenchymal cells into ameloblasts and odontoblasts occur during bell stage. The pulp is initially called as dental papilla. The differentiation of odontoblasts from undifferentiated ectomesenchymal cells is accomplished by interaction of cell and signaling molecules mediated through basal lamina and extracellular matrix.
Cell free zone of Weil: Central to odontoblasts is subodontoblastic layer. The rim of the enamel organ. Development of tooth showing cap stage Fig. The odontoblastic cell bodies form the odontoblastic zone whereas the odontoblastic processes are located within predentin matrix.
The formation of dentin by odontoblasts heralds the conversion of dental papilla into pulp. The junction of inner and outer enamel epithelium at the basal margin of enamel organ represent the future cementoenamel junction. Odontoblastic layer at the pulp periphery b. The zones are as following: Diagram showing odontoblasts The morphology of odontoblasts reflects their functional activity and ranges from an active synthetic phase to a quiescent phase.
Cells 1. Odontoblasts are columnar in shape while osteoblasts and cementoblast are polygonal in shape. Irritated odontoblast secretes collagen. These are spindle shaped cells which secrete extracellular components like collagen and ground substance Fig. All exhibit highly ordered RER.
The cells found in greatest numbers in the pulp are fibroblasts. Odontoblasts synthesize mainly type I collagen. Contents of the pulp I. Odontoblasts leave behind cellular processes to form dentinal tubules while osteoblasts and cementoblast are trapped in matrix as osteocytes and cementocytes. Similar characteristic features of odontoblasts. Ultrastructure of the odontoblast shows large nucleus which may contain up to four nucleoli.
They also secrete sialoproteins. Pulp and Periradicular Tissue contains plexuses of capillaries and small nerve fibers ramification. Macrophages Plasma cells Mast cells II. Odontoblasts 2. They are first type of cells encountered as pulp is approached from dentin. Capillaries IV. Cell rich zone: This zone lies next to subodontoblastic layer. Collagen fibers. Draining to submandibular. In the crown of the fully developed tooth. These are particularly numerous in the coronal portion of the pulp.
It contains large vessels and nerves from which branches extend to peripheral layers. Glycosaminoglycans Substance. Difference between odontoblasts. Histology of pulp showing fibroblasts 9. The number of odontoblasts has been found in the range of Water III. Subodontoblastic plexus of Raschkow. Undifferentiated mesenchymal cells 4. Principal cells are fibroblasts with collagen as ground substance.
Defense cells. Blood Vessels. Fibroblasts 3. Golgi bodies are located centrally. It contains fibroblasts. Type I Type II 2. Nucleus is situated at basal end. They also eliminate excess collagen by action of lysosomal enzymes. Odontoblasts Fig. Pulp core: It is circumscribed by cell rich zone. Undifferentiated mesenchymal cells are descendants of undifferentiated cells of dental papilla which can dedifferentiate and then redifferentiate into many cell types.
They all produce matrix composed of collagen fibers and proteoglycans capable of undergoing mineralization. Matrix 1. They appear as large oval or spindle shaped cells which are involved in the elimination of dead cells. Defence cells: In normal pulps. They are major cell type in micro abscesses for mation and are effective at destroying and phagocytising bacteria and dead cells.
The overall collagen content of the pulp increases with age. This fact is of practical significance when a pulpectomy is performed during the course of endodontic treatment. Collagen is synthesized and secreted by odontoblasts and fibroblasts. Textbook of Endodontics Fig. In older pulps. Mast cells: On stimulation. This reduction. Fibers are more numerous in radicular pulp than coronal and greatest concentration of collagen generally occurs in the most apical portion of the pulp.
Ground Substance The ground substance of the pulp is part of the system of ground substance in the body. Glycosaminoglycans b.
Engaging the pulp with a barbed broach in the region of the apex affords a better opportunity to remove the tissue intact than does engaging the broach more coronally. These are corkscrew like originating between odontoblasts and pass into dentin matrix.
Glycoproteins c. In peripheral pulp. Histiocytes and macrophages: They originate from undifferentiated mesenchymal cells or monocytes. They appear at the site of injury after invasion by neutrophils. They are associated with injury and resultant immune response. Thus their presence indicates presence of persistent irritation. The fibers are principally type I and type III collagen. Cells taking part in defence of pulp Depending on the stimulus.
These cells are found throughout the cell-rich area and the pulp core and often are related to blood vessels. Fibers produced by these cells differ in the degree of crosslinkage and variation in hydroxyline content. Collagen with age becomes coarser and can lead to formation of pulp stones. Chief components of ground substance are: Polymorphonuclear leukocytes: Most common form of leukocyte is neutrophil.
It is a structureless mass with gel like consistency forming bulk of pulp. When these cells are examined under light microscope. Pulp and Periradicular Tissue Functions of ground substance: Forms the bulk of the pulp.
Lymphatic Vessels Flow Chart 2. Mature pulp has an extensive and unique vascular pattern that reflects its unique environment.
Diagram showing circulation of pulp Blood passes from capillary plexus into venules which constitute the efferent exit side of the pulpal circulation and are slightly larger than corresponding arterioles. The arterioles course up through radicular pulp and give off branches which spread laterally towards the odontoblasts layer and form capillary plexus.
Arterial supply of teeth As they pass into coronal pulp. Venules enlarge as they merge and advance toward the apical foramen Flow Chart 2.
Supports the cells. This network provides odontoblasts with rich source of metabolites. Alexander et al in found that these enzymes can degrade the ground substance of the pulp by disrupting the glycosaminoglycan — collagen linkage. Depolymerization by enzymes produced by microorganisms found in pulpal inflammation may change ground substance of the pulp. Acts as medium for transport of nutrients from the vasculature to the cells and of metabolites from the cells to the vasculature.
Alterations in the composition of ground substance caused by age or disease interfere with metabolism. Blood vessels which are branches of dental arteries consisting of arterioles enter the dental pulp by way of apical and accessory foramina. Efferent vessels are thin walled and show only scanty smooth muscle.
Another factor contributing to elevated pulp pressure on reclining position is effect of posture on the activity of sympathetic nervous system. Textbook of Endodontics Flow Chart 2. When stimulated by electrical stimulus epinephrine containing LA. Presence of discontinuities in vessel walls. In other words. Regulation of Pulpal Blood Flow Walls of arterioles and venules are associated with smooth muscles which are innervated by unmyelinated sympathetic fibers.
Temperature changes a. Pulpal Response to Inflammation Whenever there is inflammatory reaction. General anesthetics: General anesthetics have shown to produce effect on the velocity of blood flow in the pulp. Local anesthetics: The effect of local anesthetics on pulp vasculature is mainly due to presence of vasoconstrictor in anesthetic solution.
They exit via one or two large vessels through the apical foramen. Decrease in temperature: It has been seen that at temperature lower than. Diagram showing regulation of pulpal blood flow Effect of Posture on Pulpal Flow In normal upright posture. Lymphatic can be differentiated from small venules in following ways: For example. On lying down. Lying down will reverse the effect leading to increase in blood flow to pulp. The escaping fluid accumulates in the pulp interstitial space.
Absence of RBC in their lumina. In severe inflammation. When a person is upright. Clinical Correlation 1. These changes further lead to increased vascular permeability. Since space in the pulp is confined so. Lymphatic drainage of teeth and radicular regions of the pulp. Venous drainage of teeth Flow Chart 2. Increase of temperature: The dental pulp contains both sensory and motor nerves.
Also the individual axons may branch into numerous terminal filaments which enter the dentinal tubules Fig. The unmyelinated fibers are surrounded by single layer of Schwann cells. Myelin appears to be internal proliferation of Schwann cells.
Endodontic therapy: During endodontic therapy. Nerve supply of teeth Nerve supply of teeth Fig.
This is because of increase diameter of the vessels in the central part of the pulp. The nerve fibers enter the pulp through apical foramen along with blood vessels. After entering the pulp. The myelin sheath is largely composed of fatty substances or lipids and proteins. With increasing age. The sensory nerves are encased in myelin sheath. Regardless of the nature of sensory stimulus.
Diagram showing nerve density at different areas of the tooth Flow Chart 2. Pain is complex phenomenon which is in form of the evoked potential in the tooth that initiated signals to the brain. Electrical pulp tester stimulates A delta fibers first because of their lower threshold. The nerve fibers are classified according to their diameter. The resting potential of the neuron depends on the selective permeability of plasma membrane and sodium pump of the cell.
Not well localized 4. As the impulse moves away. Difference between A-delta and C-fibers A-delta fibers Fig. Diagram showing structure of a neuron Fig. The cell information. Dull throbbing. The pain receptors transmit their message to the central nervous system at different rates depending upon size. This depolarization during passage of excitation along the neuron constitutes the action potential or a nerve impulse. Unmyelinated 3. The physiology of nerve conduction is related to changes in cell membrane.
Stimulation of a neuron causes it to depolarize in the region of stimulus and subsequently adjacent areas of cell membrane are also depolarized. Slow conduction velocity 0. The fibers having largest diameter are classified as A fibers while those having smallest diameter are classified as C-fibers Fig.
The C fibers are slower conducting fibers and are considered responsible for dull and throbbing pain. As the intensity of stimulus is increased along with A-delta fibers. Pain is well localized 4.
The unmyelinated nerves are usually found in autonomic nervous system. When the nerve is at rest. Have low threshold 5. Diagram showing nerve fibers of pulp 14 1.
Because of this. These neurotransmitters generate an electrical impulse in the receptors of the dendrite of other neurons. Have high threshold 5.
When the impulse arrives at synaptic terminals. During excitation. Myelinated 3. Textbook of Endodontics absent.
The A delta fibers are faster conducting and are responsible for localized. Basic Structure of a Neuron The basic unit of nervous system is the neuron Fig. Physiology of nerve conduction Subsequently. The cell membrane of the neuron is composed of bimolecular layer of lipid between two layers of protein. Diagram showing pulp anatomy of anterior tooth Fig. This space is called pulp cavity which is divided into pulp chamber and root canal Fig.
Diagram showing pulp cavity of posterior tooth C-fibers can show response because these are more resistant to hypoxic conditions or compromised blood flow. A specific stimulus such as caries leads to the formation of irritation dentin.
Canal orifices are openings in the floor of pulp chamber leading into the root canals Fig. The change in pulp cavity anatomy results from age. The roof of pulp chamber consists of dentin covering the pulp chamber occlusally. The shape of root canal varies with size.
In the anterior teeth. But in case of multirooted teeth. As the external morphology of the tooth varies from person to person. The send free nerve endings into dentinal tubules.
With time. In most cases. Commonly curvature is found along its length which can be gradual or sharp in nature Fig. A straight root canal throughout the entire length of root is uncommon. Straight and curved root canal Fig. Continuous deposition of new layers of cementum causes change in foramen anatomy. Majority of single rooted teeth have single canal which terminate in a single foramina. Multiple foramina are frequent phenomenon in multirooted teeth. Diagram showing relationship between shape of root and number of root canals.
In young newly erupted teeth. This whole process resulted in new foramen away from the apex. Average size of maxillary teeth is 0. The total volume of all permanent pulp organs is 0. Thus we can say that dentinocemental junction does not necessarily occur at the apical end of root. The inner surface of the apex becomes lined with the cementum which may extend for a short distance into the root canal. Root canals can be round. The apical foramen is an aperture at or near the apex of a root through which nerves and blood vessels of the pulp enter or leave the pulp cavity Fig.
Change in shape and location of foramen is seen during post-eruptive phase due to functional forces tongue pressure. Diagram showing opening of canal orifices in the pulp chamber Fig. Reduction in size of pulp cavity because of formation of secondary and tertiary dentin 16 Fig.
Radiographic appearance of pulp cavity According to Orban. The dental nerve divides into multiple branches as it traverses the bone. The nerve twigs either end among the stroma of the pulp or terminate among the odontoblasts. This nerve proceeds coronally with afferent blood vessels and later divides into cuspal nerves at the coronal portion of the tooth.
Pulp and Periradicular Tissue Fig. Nutrition of dentin 3. Diagram showing accessory and lateral canals Fig. Pulp transmits pain. Then the nerves enter the apical foramina and unite to form common pulpal nerve. Odontoblasts also have the ability to form dentin at sites when dentin continuity has been lost. Formation of dentin 2. This fluid travels into the dentin through the network of tubules formed by the odontoblasts to contain their processes.
Apical foramen through which nerves and blood vessels enter or leave the pulp cavity Fig. Innervation of Tooth Through the nervous system. The formation of reparative dentin and sclerotic dentin are defense mechanisms of the tooth. At the apical alveolar plate. If vessel is located in this area. Nutrition of Dentin Nutrients exchange across capillaries into the pulp interstitial fluid.
Diagram showing variation in position of cementodentinal junction Accessory canals: They are lateral branches of the main canal that form a communication between the pulp and periodontium. Odontoblasts are differentiated from the dental papilla adjacent to the basement membrane of enamel organ which later deposits dentin.
On approaching the cell free zone of pulp. Defense of Tooth Odontoblasts form dentin in response to injury particularly when original dentin thickness has been compromised as seen in caries. Pulp primarily helps in: Formation of Dentin It is primary function of pulp both in sequence and importance. Exact mechanism of their formation is not known but they occur in areas where there is premature loss of root sheath cells because these cells induce formation of odontoblasts.
Defense of tooth 1. Teeth are supplied by the maxillary and mandibular divisions of the trigeminal V nerve.: Accessory canals contain connective tissue and vessels and can be seen anywhere from furcation to apex but tend to more common in apical third and in posterior teeth Fig. Pulp performs four basic functions i.
Innervation of tooth 4. They also develop where developing root encounters a blood vessel. With age. These changes can be natural or may be result of injury such as caries. Regardless of the cause. Emergency treatment. The normal pulp. Pulp inflammation in the primary tooth. Wound dressings — characteristics, modes of action and reported clinical success rates. Objectives of pulp treatment. Operative treatment procedures. Indications and contra-indications for pulp treatment in primary teeth.
Future directions. Part 2 The Necrotic Pulp. Evidence for the essential role of micro-organisms in apical periodontitis. Routes of microbial entry to the pulpal space. Modes of colonization. Ecological determinants for microbial growth in root canals. Methods for studying the root canal microflora. Composition of the endodontic microflora.
Association of signs and symptoms with specific bacteria. Concluding remarks. The nature of apical periodontitis. Interactions with the infecting microbiota. Clinical manifestations and diagnostic terminology. Acute periapical infections as the origin of metastatic infections. Chronic periapical infections as origin of metastatic infections. Objectives and general treatment strategies. Scheme for a routine procedure in RCT. Considerations in complex cases. Effects of RCT on the intracanal microbiota.
Management of symptomatic lesions. Part 3 Endodontic Treatment Procedures.