Pulp Flashcards by John Fixari

Pulp

Soft connective tissue that supports dentin

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What are some unique features of pulp?

Vascular

Not calcified

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What is the embryonic origin of the pulp?

Ectoderm - neural crest ectomesenchyme - dental papilla

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What are some contents of pulp?

Cells and cellular elements
Blood and lymphatic vessels
Extracellular matrix

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What are the functions of pulp?

Inductive
Formative
Nutritive
Protective
Defensive/Repairative

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Inductive function of pulp

Very early in development, it is involved in inducing transition from dental lamina to bud stage

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Nutritive function of pulp

Helps supply the dentin with nutrients and water

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What changes might an endodontically treated tooth undergo?

Dentin will become more brittle because pulp can bring nutrients

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What are the protective mechanisms of the pulp?

Sensory mechanism

Barrier

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Sensory mechanism of pulpal protection

Nerve fibers travel in the pulp, which inform us if the tooth is injured, causing us to use the tooth less, preventing further damage

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Barrier mechanism of pulpal protection

Pulp are under positive pressure at odontoblast junctions - if there is a break, the positive pressure forces things out into the oral cavity, protecting the underlying pulp

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Defensive/repairative mechanisms of pulp

Immune system

Formation of new dentin and pulp

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What are the types of foramina of the pulp?

Apical foramen

Accessory foramen

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What happens to pulp chambers as we age?

They get smaller - making endo more difficult with older patients
Pulp has more cells at a young age and more extracellular matrix in older ages

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T/F - the pulp is never calcified

False - it is common to have ectopic calcifications

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What are the types of ectopic calcifications?

Pulp stones

Diffuse calcifications

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Pulp stones

Ectopic calcification commonly found in pulp chamber in crown of the tooth
Spherical or ovoid
No clear cause

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Diffuse calcifications

Ectopic calcification often found near blood vessels

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Are ectopic calcifications problematic?

Not likely, mostly likely just an annoyance if you’re an endodontist

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What are the zones of the pulp?

Odontogenic zone

Pulp core

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Odontogenic zone layers

Odontoblast layer
Cell free zone
Cell rich zone

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Odontoblast layer

Most superficial layer of odontogenic zone
Single layer of odontoblasts lining the pulp dentin border
Can look like multiple layers, but its likely an artifact of how the slide was cut

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Cell free zone

Cells are less prominent

Middle layer of odontogenic zone

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Cell rich zone

Increase concentration of fibroblasts

Deep layer of odontogenic zone

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Pulp core

Lots of fibroblasts, blood vessels, and nerves

What cells are found in the pulp?

Odontoblasts Fibroblats Immune system cells Stem cells

Odontoblasts

Cells that make dentin | Has processes that go into dentinal tubules

Fibroblasts

Confined in the pulp Secrete ECM of the pulp -mostly collage, but other proteins as well

What are the 2 types of immune system cells in the pulp?

Resident immune cells | Inflammation cells

What are the types of Resident Immune cells

Macrophages Lymphocytes Eosinophils Dendritic cells

Dendritic cells

Sit at the PD order, surveying the environment | If there's an infection, these present the infection to the immune system

Inflammation cells

When you get a tooth infection, these cell numbers increase Plasma cells Mast cells PMNs

Stem cells

Source of replacement for odontoblasts or fibroblasts High capacity of self reneway Mutlipotent - can generate multiple cell types

What are components of the ECM of the pulp?

Proteoglycas Glycoproteins Collagen

Proteoglycan function in pulp

Gelatinous matrix for diffusion of molecules through the pulp Help control when and how much collagen is secreted Water retention - important for keeping pulp moist and keeping positive pressure

Glycoprotein function in the pulp

Cell adhesion to the ECM

Collagen function in the pulp

Tensile strength

What types of collagen are found in the pulp?

I and III

Odontoblast function in the pulp

Dentinogenesis Nutrients to dentin Immune - can secrete immunity molecules when needed

What are the types of junctions between odontoblasts?

Desmosomes and adherens junction Gap junctions Tight junctions

Desmosomes and adherens junctions

Maintain position and polarity of odontoblasts

Gap junctions

Coorinate dentinogenesis - once one odontoblasts decides to make dentin, it signals to neighbors to do the same thing using gap juncitons

Tight juncitons

Form a barrier to prevent things from diffusing between odontoblasts Sits at apical portion of cells

Why are the structures of tight junctions so complex?

The more complex they are, the better they are at keeping things out

T/F - Tight junctions prevent all things from getting between odontoblasts

False - small things can still potentially get through. Tight junctions are better at preventing large molecules from going through

What is the importance of lymphatic tissue in the pulp?

Healing - they drain proteins that accumulate during inflammation

Why does the lymphatic tissue have complex anatomy in the pulp?

To overcome challenges associated with encasement in a hard tissue

What are the types of nerve fibers in the pulp

A-delta fibers C fibers A-beta fibers

What happens to innervation during tooth eruption?

Density of innervation increases - it decreases with aging

Where do nerve fibers enter the pulp?

Apical foramen

How far do nerve fibers extend into the dentin?

We're not sure - but it's likely not all the way to the DEJ

Where is the dentin most highly innervated?

In the crown

Hydrodrynamic theory of dentinal pain

Air, solids, or cold can create a fluid wave in the dentinal tubule, which stretches the nerve fiber, activating pain

Does pain in the pulp follow the Hydrodynamic theory of dentinal pain?

No, just the dentin.

What type of pain receptors are associated with the pulp?

TRP receptors

Family of transmembrane receptors for thermal and inflammatory pain in many regions of the body Activated by many inflammatory mediators

Describe the path of pain associated with A fibers

Dental stimuli --> Hydrodynamic forces --> A-beta and A-delta fibers --> Sharp pain

Describe the path of pain associated with C fibers

Infection or trauma --> Inflammation --> C fibers --> Dull pain

What fibers can be activated by electric pulp and hot/cold testing?

A fibers

What do neuropeptides do at central endings?

They have a transmitter funciton | They bind to receptors on brain neurons and produce pain

What do neuropeptides do at peripheral endings?

They have a local regulatory function | They bing with receptors on vasculature and local cells and lead to pro-inflammatory response