Pulp Question And Answers

Pulp

Question 1. Define pulp and describe its function.
Answer:

Definition:

• The dental pulp is defined as a richly vascularized and innervated connective tissue of mesodermal origin enclosed by dentin with communications to the periodontal ligament.
• It is the soft connective tissue that supports the dentin.

Functions:

1. Inductive:

• The pulp interacts with tire oral epithelial cells and causes differentiation of dental lamina and resulting in enamel organ formation.
• The pulp also interacts with the developing enamel organ and determines a particular type of tooth.

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2. Formative:

• It produces the dentin that surrounds and protects it.
• It produces dentin both under physiological and pathological conditions.
• First of all, odontoblast present in tire pulp develops the organic matrix and helps in its calcification.
• Next, the odontoblastic process develops which is a cellular extension of the odontoblast.
• These processes lay down dentin along the tubule wall as well as at the pulp-dentin interface.

3. Nutritive:

• It nourishes the avascular dentin.
• Pulp has a rich blood supply with a vascular network around the odontoblasts.
• This vascular system supplies the odontoblast and its process present within the tubule.

4. Protective:

• Pulp carries nerves that give dentin its sensitivity.
• The nerve initiates reflexes that control the circulation of the pulp.
• Sensory nerves respond with pain to all stimuli.
• Sympathetic nerves provide stimulation to visceral motor fibers.
• These fibers terminate on the muscles of blood vessels.

5. Defensive or reparative:

• Pulp is capable of producing new dentin when required.
• Pulp responds to irritation created by any external stimuli by producing reparative dentin and mineralizing any affected dentinal tubules.
• Milder injury to the pulp lead to the focal secretion of the reactionary dentin matrix while greater injury lead to odontoblast cell death.
• Reparative dentin is formed to seal off the pulp from the source of irritation.
• The pulp contains inflammatory cells that help in the repair of the pulp.

Question 2. Describe briefly the microscopic structure of pulp.
Answer:

Structure of pulp:

• The pulp consists of

1. Interceullar substance:

• The intercellular substances are dense and gel-like in nature.
• Its appearance varies from finely granular to fibrillar.
• It is composed principally of glycosaminoglycans, glycoproteins, and water.
• With age its composition changes.
• Initially, there occurs chondroitin A, B and hyaluronic acid, and glycoproteins in abundant amounts.
• Later all these substances decrease in amount.
• This reduction interferes with the function producing metabolic changes.
• This also results in irregularities in mineral deposition.

Pulp Functions:

• It supports the cells.
• It acts as the medium for the transport of nutrients from the vasculature to tire cells and of metabolites from the cells to the vasculature.

2. Fibroblasts:

• It is the most numerous cell type in the pulp.
• They are particularly numerous in the tire coronal portion of the pulp.
• They have typical stellate shapes.
• Adjacent cells are joined by intercellular junctions.
• The cytoplasm is homogenous with the abundant rough-surfaced endoplasmic reticulum, mitochondria, and other organelles.
• In young pulps, fibroblasts have a plump, cytoplasm and an extensive amount of all organelles for synthesizing matrix.
• With age, fibroblasts appear as flattened spindle-shaped cells with dense nuclei.

Fibroblasts Functions:

• Fibroblasts form and maintain the pulp matrix.
• They are capable of ingesting and degrading collagen when appropriately stimulated.
• They play an important role in inflammation and healing.
• They release inflammatory mediators, cytokines, and growth factors.

3. Fibers:

• The matrix of pulp consists of collagen fibers.
• These fibers exhibit typical cross striations at 64 nm and range in length from 10-100 nm or more.
• In the young pulps, single fibrils of collagen are found scattered between the pulp cells.
• With age, the collagen fibers increase in amount and organize into fiber bundles.
• The fibers are principally type 1 and type 3 collagen.
• The greater concentration of collagen generally occurs in the most apical portion of the pulp.
• Their presence may be related to environmental trauma.

4. Undifferential mesenchymal cells:

• The connective tissue cells of the pulp are derived from it.
• Depending on the stimulus, these cells may give rise to odontoblasts, fibroblasts, or macrophages.
• They are found throughout the cell-rich area and the pulp core.
• They appear as large, polyhedral cells possessing a large, centrally placed nucleus.
• They have abundant cytoplasm.
• They are the primary cells in very young pulp, but few are seen in pulps after root completion.
• With age, there is a reduction in these cells which reduces the regenerative potential of the pulp.

5. Odontoblast:

• They are the second most prominent cell in the pulp they are tall columnar cells with large oval nuclei
• The odontoblast morphology and its organelles vary with the functional activity of the cell.

Odontoblast Functions:

• Function primarily as secretory cells.
• They synthesize and secrete collagen from dentin and also the ground substance.

6. Defence cells:

• They are.
• Histiocyte or macrophage:
• They have irregularly shaped cells with short blunt processes.
• Their nucleus is smaller and more rounded and granular cytoplasm.

Mast cells:

• They are seen along vessels in the inflamed pulp.
• Their number increases during inflammation of the pulp.

Plasma cells:

• Their nucleus is small and the cytoplasm is basophilic.
• They are seen during inflammation and produce antibodies.

7. Other cells:

Eosinophil and lymphocytes:

• They are found extravascularly in the pulp.

Dendritic cells:

• They are bone-derived cells.
• Found in and around the odontoblast layer.

Dendritic cells Function:

• They capture and present foreign antigens to T-cells.

Question 3. Describe briefly pulp.
Answer:

Definition:

The dental pulp is defined as the richly vascularised and innervated connective tissue of mesodermal origin enclosed by dentin with communications to the periodontal ligament.

Functions:

1. Formative:

• It produces the dentin that surrounds it.

2. Nutritive:

• It nourishes the avascular dentin.

3. Protective:

• It carries nerves that give dentin its sensitivity.

4. Reparative:

• It is capable of producing new dentin when required.

5. Inductive:

• Pulp interacts with oral epithelium cells and causes differentiation of dental lamina and results in enamel organ formation which determines the type of tooth.

Anatomy:

• The dental pulp occupies the center of each tooth and consists of soft connective tissue.
• The pulp present in the crown is called coronal pulp and the pulp present in the root is called radicular pulp.
• The pulp consists of apical foramen and accessory canals.
• The apical opening is found on the lateral side of the apex.
• Frequently, there are two or more foramina separated by a portion of dentin and cementum.

Structure:

• Four distinct zones can be distinguished in the pulp. They are.

1. Odontoblastic zone: At the pulp periphery.
2. Cell-free zone of Weil:
   • Beneath the odontoblasts.
   • It is prominent in the coronal pulp.
3. Cell-rich zone:
   • Adjacent to the cell-free zone.
   • Cell density is high in this zone.
4. Pulp core:
   • It is characterized by the major vessels and nerves of the pulp.

Cellular elements:

1. Odontoblasts:

• They form a layer lining the periphery of the pulp and have a process extending into dentin.
• They are columnar cells with basal nuclei.
• They synthesize and secrete collagen from dentin.

2. Fibroblasts:

• They are the most prominent cells of pulp.
• They are stellate shape cells with extensive processes
• They form and maintain the pulp matrix.
• They are capable of ingesting and degrading collagen.

3. Undifferential ectomesenchyme cells:

• Depending on the stimulus, these cells may give rise to odontoblasts, fibroblasts, or macrophages.

4. Defence cells:

• Histiocytes or macrophages
• Mast cells
• Plasma cells.

5. Other cells:

• Eosinophils and lymphocytes.
• Dendritic cells

Matrix and ground substance:

• Matrix consists of collagen fibers and ground substance composed of principally glycosaminoglycans, glycoproteins, and water.

Blood vessels:

• The pulp is supplied by superior alveolar and inferior alveolar vessels.

Lymph vessels:

• The lymph vessels of anterior teeth drain into submental lymph nodes and that of posterior teeth into submandibular and deep cervical lymph nodes.

Question 4. Describe briefly about age changes in the pulp.
Answer:

Age changes in pulp:

1. Cell changes:

• There is a reduction in the number and size of cells and cellular organelles.
• Fibroblasts exhibit less perinuclear cytoplasm and possess long, thin cytoplasmic processes.

2. Fibrosis:

• Accumulation of diffuse fibrillar components as well as bundles of collagen fibers appear.
• The increase in the fibers in the pulp organ is gradual and generalized.

3. Vascular changes:

• Atherosclerotic plaques may appear in pulpal vessels.
• The outer diameter of vessel walls increases.
• Calcifications occur in surrounding vessels.
• Endothelium shows numerous pinocytic vesicles, microvesicles, and microfilaments.

4. Pulp stones or denticles:

• They are nodular, calcified masses appearing in the coronal and radicular pulp.
• They are asymptomatic unless they impinge on nerves or blood vessels.

5. Other changes:

• Diffuse calcifications are usually found in the root canal.
• The pulp becomes smaller in size due to successive layers of secondary dentin formation.
• Reduction in size of apical foramen occurs
• Reduction in pulpal sensitivity due to nerve degeneration.
• Pulp shows a reduced resistance to infection due to a reduction in cells.

Question 5. Enumerate structures in the pulp. Write in detail about the odontoblastic layer and its function.
Answer:

Structure of pulp:

• It consists of

1. Intercellular substance.
2. Fibroblasts
3. Fibers
4. Undifferential mesenchymal cells.
5. Odontoblasts.
6. Defense cells.
7. Blood vessels
8. Lymph vessels.
9. Nerves and nerve ending.

Odontogenic layer:

• Histologically four distinct zones are recognized they are.
• They are.

1. Odontogenic layer
2. Cell-free zone
3. Cell-rich zone
4. Pulp core

Odontogenic layer:

• It occurs adjacent to the prevention
• It consists of odontoblasts which are the second most prominent cell in the pulp after fibroblasts.
• These cells line the periphery of the pulp with their long axis at right angles to the pulp surface.
• The odontoblastic process extends into the dentinal tubules.

Number:

• The number of odontoblasts corresponds to the number of dentinal tubules.
• It ranges from 59,000 to 76,000 per square millimeter in coronal dentin to lesser in root dentin.

Shape:

• Odontoblasts in the crown are also larger than odontoblasts in the root.
• In the crown, they appear columnar, whereas in the midportion on the pulp, they are more cuboid, and in the apical part more flattened.

Nucleus:

• It is situated basally towards the pulpal side.
• It is oval in shape.

Cell organelles:

• Odontoblast has a prominent Golgi apparatus, abundant mitochondria, numerous vesicles, much endoplasmic reticulum, and numerous mitochondria scattered throughout the cell.
• The odontoblastic process contains no endoplasmic reticulum but during the active phase contains occasional mitochondria and vesicles.

Variation:

• The morphology of odontoblasts varies with their functional activity.

1. Active cell:
   • Appear elongated
   • The nucleus is basally located
   • Possess basophilic cytoplasm and prominent Golgi apparatus.
2. Resting cell:
   • It is stubby.
   • Posses little cytoplasm.
   • The nucleus is more hematoxyphilic.

Functions:

• Odontoblasts function primarily as secretory cells.
• They also secrete ground substances.
• They release inflammatory chemokine IL-8, chemotactic for neutrophils.
• Odontoblasts contain nitric oxide synthetase which plays an important role in vasodilation and blood pressure regulation.

Question 6. Odontogenic zone of pulp.
Answer:

Question 7. Age changes and clinical considerations of the pulp.
Answer:

Clinical considerations:

• Pulpitis- It is a pulpal response to trauma occurring due to bacterial infection or physical trauma.
• Pulpitis can be focal reversible pulpitis which is of milder form or chronic hyperplastic pulpitis characterized by an exposed pulp chamber with a protruding mass of granulation tissue.
• Inflammation occurring within the pulp called internal resorption results in pulpal tissue appearing pink through the enamel (pink tooth).
• A pulpal infection can spread and result in granulomas, abscesses, and cysts.
• The shape of the pulp chamber and pulpal horns is to be considered before any dental procedures.
• The shape of the apical foramen, its size, presence, and absence of accessory canals affect the root canal treatment.
• Periodontol disease has an impact on the pulp.
• Pulp pain worsens with the degree of inflammation.
• A vital pulp is essential for good dentition.
• In response to orthodontic forces, the pulp shows cell damage, inflammation, vasodilation, and healing.

Question 8. Pulp classifications
Answer:

• Calcifications within pulp are called pulp stones.
• They are modular, discrete calcified masses that have a calcium-phosphorous ratio comparable to that of dentin.
• They may be single or multiple.

Site:

• They appear in either or both the coronal and root portions of the pulp.
• They may be seen in functional as well as embedded unerupted teeth.
• They are frequently found at the orifice of the pulp chamber or within the root canal.

Histology:

• They usually consist of concentric layers of mineralized tissue formed by surface accretion around blood thrombi, dying or dead cells, or collagen fibers.
• Occasionally a pulp stone may contain a tubule.

Types:

1. True pulp stones:

• They have dentinal tubules and odontoblastic processes.
• They occur most commonly close to the apex of the root.

False pulp stones:

• They do not have dentinal tubules.
• They appear as concentric layers of calcified tissue.
• They are common in the coronal pulp.
• They are formed around dead cells of collagen.

2. Free pulp stones:

• They are entirely surrounded by pulp tissue.

Attached are pulp stones:

• They are partly fused with dentin.

Embedded pulp stones:

• They are entirely surrounded by dentin.

Significance:

• The presence of pulp stones reduces the overall number of cells within the pulp.
• They play an important role in the debridement and enlargement of the root canal system during endodontic treatment.

Question 9. Functions of pulp
Answer:

1. Inductive

• The pulp interacts with the oral epithelial cells and causes differentiation of dental lamina and results in enamel organ formation.

2. Formative

• This is the primary function of the pulp.
• It produces the dentin that surrounds and protects it.

3. Nutritive

• It nourishes the avascular dentin.

4. Protective

• Pulp carries nerves that give dentin its sensitivity
• Pulp lacks the receptors for heat, touch, pressure, chemicals, and proprioception.
• Any stimulus will elicit a response in the form of pain only.
• It responds to pain because it has free nerve endings.

5. Defensive or reparative

• Pulp is capable of producing new dentin when required.

Question 10. Zones of pulp
Answer:

1. Odontoblastic zone:

• It occurs adjacent to the prevention
• It consists of odontoblasts lining the periphery of the pulp

Odontoblasts:

• They line the periphery of the pulp
• The odontoblastic processes extend into dentinal tubules
• Their number corresponds to the number of the dentinal tubules
• In the crown, they appear columnar, more cuboidal in the mid portion, and flattened in the apical portion Nucleus is situated basally towards the pulp
• Odontoblast has a prominent Golgi apparatus, abundant mitochondria, numerous vesicles, much endoplasmic reticulum

2. Cell-free zone of Weil:

• It is prominent in the coronal pulp
• It is a space in which the odontoblasts may move pulpward during tooth development and then to a certain extent in functioning teeth

3. Cell-rich zone:

• Adjacent to the cell-free zone
• Cell density is high in this zone
• It is composed of fibroblasts and undifferentiated mesenchymal cells

4. Pulp core:

• It is characterized by the major vessels and nerves of the pulp

Question 11. Histology of pulp
Answer:

• The pulp consists of

1. Intercellular substances:

• It is dense and gel-like in nature
• It is composed principally of glycosaminoglycans, glycoproteins, and water
• With age its composition changes

Functions:

• It supports the cells
• Acts as a medium for the transport of nutrients from the vasculature to the cells and of metabolites from the cells to the vasculature

2. Fibroblasts:

• It is the most abundant cell of the pulp
• Numerous in the coronal part of the pulp
• They are typically stellate-shaped cell
• Adjacent cells are joined by intercellular junctions

Functions:

• They form and maintain the pulp matrix
• They are capable of ingesting and degrading collagen when appropriately stimulated
• They play an important role in inflammation and healing
• They release inflammatory mediators, cytokines, and growth factors

3. Fibres

• The matrix of pulp consists of collagen fibers – type 1 and type 3
• A greater concentration of fibers is present in the most apical portion of the pulp
• Their presence may relate to environmental trauma

4. Undifferentiated mesenchymal cells

• Depending upon the stimulus, these cells may give rise to odontoblasts, fibroblasts, or macrophages
• Found throughout the cell-rich zone and pulp core
• They have abundant cytoplasm
• They appear as large, polyhedral cells possessing large, centrally placed nucleus

5. Odontoblasts

• They line the periphery of the pulp
• The odontoblastic processes extend into dentinal tubules
• Their number corresponds to the number of the dentinal tubules
• In the crown, they appear columnar, more cuboidal in the mid portion and flattened in the apical portion.

Functions:

• Synthesize and secrete collagen of dentin and also ground substance

6. Defence cells

• Histiocytes or macrophage
• Mast cells
• Plasma cells

7. Other cells

• Eosinophil and lymphocytes
• Dendritic cells

Question 12. Cementicles
Answer:

• A canticle is a small, spherical, or ovoid calcified mass embedded within or attached to the cementum layer on the root surface of a tooth or lying free within the periodontal ligament
• They tend to occur in elderly individuals.

Types:

There are 3 types:

• Free cementite – not attached to the cementum
• Attached (sessile) cementite – attached to the cementum surface (also termedexocementosis)
• Embedded (interstitial) cementite- with advancing age, the cementum thickens, and the canticle may become incorporated into the cementum layer.

Features:

• They may appear singly or in groups
• Most commonly found at the tip of the root.
• Their size is variable (about 0.2 mm – 0.3 mm in diameter)
• Cementicles are usually acellular and may contain either fibrillar or fibrillar cementum, or a mixture of both
• Cementicles are the result of dystrophic calcificationCementicles are thought to form when

Causes:

• Calcification due to degenerative changes in the epithelial cell rests of Malassez
• Calcification of thrombosed capillaries in the periodontal ligament
• Microtrauma to Sharpey’s fibers

Question 13. Cellular elements of the pulp.
Answer:

Question 14. Pulp stones.
Answer:

• They are modular, discrete calcified masses appearing in either or both the coronal and root portions of the pulp.
• They are usually asymptomatic unless they impinge on nerves or blood vessels.

Types:

1. True and false pulp stones.
2. Free, attached, and embedded pulp stones
3. Discrete and diffuse.

Significance:

• They play an important role in the debridement and enlargement of the root canal system during endodontic treatment.

Question 15. Pulp.
Answer:

The dental pulp is defined as the richly vascularized and innervated connective tissue of mesodermal origin enclosed by dentin with communications to the periodontal ligament.

Functions:

• Formative
• Nutritive
• Protective
• Reparative
• Inductive.

Zones:

• Odontoblastic zone
• Cell-free zone for Weil
• Cell rich zone
• Pulp core.

Cellular elements:

• Odontoblasts
• Fibroblasts
• Undifferentiated mesenchymal cells
• Defense cells.
• Other cells like eosinophils and dendritic cells.

Question 16. Zones of pulp.
Answer:

1. Odontoblastic zone:

• It occurs adjacent to the prevention
• It consists of odontoblasts lining the periphery of the pulp.

2. Cell-free zone of Weil:

• It is prominent in the coronal pulp.
• It is a space in which the odontoblast may move pulpward during tooth development and then to a certain extent in functioning teeth.
• It is inconspicuous during the early stages of rapid dentinogenesis.

3. Cell-rich zone:

• Adjacent to the cell-free zone Cell density is high in this zone
• It is composed of fibroblasts and undifferentiated mesenchymal cells.

4. Pulp core:

• It is characterized by the major vessels and nerves of the pulp.

Question 17. Functions of pulp.
Answer:

1. Inductive:

• Pulp induces the differentiation of dental lamina and results in enamel organ formation.

2. Formative:

• Pulp produces the dentin that surrounds it.

3. Nutritive:

• Pulp nourishes the avascular dentin.

4. Protective:

• It carries nerves that give dentin its sensitivity.

5. Reparative:

• Pulp is capable of producing new dentin when required.

6. Defensive:

• Pulp reacts to injury through the inflammatory process.
• Pulp forms reparative dentin in response to irritations.

Question 18. Age changes in the pulp.
Answer:

• Reduction in number and size of cells of pulp.
• Fibrosis of pulp due to increased content of collagen.
• Change in the morphology of the cell and its organelles appearance of atherosclerotic plaque in pulpal vessels.
• Calcifications occur in surrounding vessels.
• Pulp shows a reduced resistance to infection due to a reduction in cells.
• Reduction in pulpal sensitivity and size of the apical foramen.
• The pulp becomes smaller in size.
• Pulp stones appear in coronal as well as root portions of the pulp.

Question 19. Subodontoblastic plexus of raschkow.
Answer:

• The dentinal pulp is richly innervated
• Nerves enter the pulp through the apical foramen and extend occlusal through the pulp core.
• Each nerve fiber provides at least eight terminal branches.
• These branches ultimately form an extensive plexus of nerves in the cell-free zone in the crown portion of the tooth.
• This plexus of nerves is called the odontoblastic plexus of raschkow.
• It is demonstrated in silver nitrate-stained sections under a light microscope or by immunocytochemical technique.
• Such a plexus is absent in root portions.

Question 20. Decalcifying agents
Answer:

Uses:

• To study the structure of tooth and pulp calcification
• Evaluate the biological response of pulp to the restorative material

Requirements:

• Ensure complete removal of calcium
• Causes minimum damage to cells and tissues
• Causes nonimpairment to substantial staining
• Decalcifies at a reasonable speed

Agents used:

• EDTA
• 5% nitric acid
• Formalin nitric acid
• 5% trichloroacetic acid 10% formic acid

Question 21. Accessory canals
Answer:

• Accessory canals are canals seen anywhere along the root

Extend:

• Radicular pulp laterally to periodontal tissue
• Most numerous in the apical third of the root

Cause of formation:

• Premature loss of root sheath cells
• Presence of blood vessels in the area of dentin formation
• Hard tissue develops around blood vessels making a lateral canal from radicular pulp

Significance:

• Causes spread of infection from pulp to periodontal ligament and from periodontal ligament to pulp