16a dentin-pulp complex

What is the dentin pulp complex

A functional structural and embryological unit

where does an embryological unit derive from

ectomesenchyme

What does the embryological unit form

Papilla of the tooth germ

why is the dentin pulp complex a structural unit

it has odontoblastic extensions in the dentin

What does the pulp maintain

the vitality of the dentin

What does the dentin do to the pulp

The dentin protects the pulp

What kind of tissue is dentin

Mineralised

What kind of tissue is pulp

Soft connective

What is the only soft tissue in the tooth

pulp

why does the pulp become smaller

Continuous deposition of dentin

Where does the pulp occupy

Center of each tooth in the pulp chamber

What is the pulp cavity

Hollow space completely surrounded by dentin

What is the layer around the pulp cavity

Hard dentin tissue layer

What does the dentin layer around the pulp cavity do to the pulp

Pulp is isolated except at the apical foramen

Why is the pulp isolated except at the apical foramen

Its the opening where nerves and vessels enter the pulp

What does the pulp cavity mirror

External shape of the tooth

What happens to the pulp Cavity with age or stimuli

Secondary and tertiary dentin deposition shrinks the pulp cavity

In molars and premolars what is the pulp chamber divided into

Pulp chamber of the crown

Rooth canal

What type of pulp is in the pulp chamber of the crown

Coronal pulp

What does the pulp chamber of the crown have

Floor and roof

Pulp horns

What are pulp hrons

Extensions that go towards the cusps

What type of pulp does the root canal have

Radicular pulp

What does the root canal have

Canals that emerge and penetrate the roots extending to the apical foramen

Mira mira

Done

The separation of coronal and radicular pulp only occurs in what type of teeth

Multirooted / multiradicular

Waht are uniradicular teeth

Teeth with only 1 root

E.g incisor

What is the pulp like in uniradicular teeth

Coronal pulp is continuous with radicular pulp

(There is no dividing line)

in the apical foramen, what does the radicular pulp connect with

Periapical tissue of the periodontal ligament

What is the periapical tissue

The periodontal ligament tissue surrounding root apex

What is Blacks undifferentiated periapex

A zone where the pulp tissue and periodontal ligament meet without a sharp barrier

how is apical foramen different from blacks undifferentiated periapex

BUP is not a separate structure - it is an area for the pulp touching the periodontal ligament

Done

Is there a barrier between pulp at apex and the periodontal ligament

No

(Susceptible to infections)

What is beyond the blacks undifferentiated periapex

Periodontal ligament

What are mesenchymal cells

They are like undifferentiated stem cells that can develop into connective tissue cells

What is the reservoir of mesenchymal cells

Periapical region

Whar can the mesenchymal cells in the periapex differentiate into

fibroblasts

Osteoblasts

Cementoblasts

What do the fibroblasts do here

Produce collagen fibers of the periodontal ligament and connective tissue

What do osteoblasts do here

Form bone around socket

What do cementoblasts do

Form cementum on root surface

How do the accessory canals pass through pulps

Laterally through the dentin to the periodontal tissue

Wht pulp do accessory canals go through

Radicular pulp (anywhere)

How are accessory canals formed

We dont know

Where are accessory canals more likley formed

Areas with premature loss of root sheath cells

Areas where the developing root connects with a blood vessels

What are root sheath cells

Cells inducing formation of ondontoblasts

Look

Done

does the dental pulp have only vascularisation and no innervation

no it has both

Where are odontoblasts located

On the periphery of the pulp

What do odontoblasts do

Produce different types of dentin

How are odontoblasts in contact with the dentin

They have extensions into the dentin / dentinal tubules

Are there more odontoblasts at the crown or the root

The crown

What type of epithelium does the coronal portion have

Pseudostratified epithelium

What type of epithelium does the root portion have

Simple columnar epithelium

is predentin immature unmineralised soft tissue that becomes dentin

Yes

Is Dentin is mature mineralised soft tissue

No

It is mature mineralised hard tissue

How does predentin become dentin

Mineralisation

What kind of epithelium are the odontoblasts arranged like in the coronal portion

Pseudostratified like

What kind of epithelium are the odontoblasts arranged like in the root portion

Simple columnar like

Are odontoblasts epithelium?

NO

Done

What are odontoblasts transformed into

Tall columnar cells with large and basal nuclei

Why are odontoblasts transformed

When they are in their maximum secretory activity

What is the RER like in the transformed odontoblast

Extensive

Large part of cytoplasm

Where is the golgi in the transformed odontoblast

located supranuclear

(Above nucleaus and underneath apical pole)

What does the apical pole face in the odontoblast

Faces the predentin

Where in the odontoblast does it extend into the dentinal tubule

The apical pole

What is the golgi in the transformed odontoblast

Developed

Numerous granules with filamentous content

Does the odontoblast have little mitochondria

No, it has many

What forms the odontoblastic layer

Junctional complexes (Desmosomes, extensions, gap junctions)

How are the junctional complexes connected

Laterally

What is the purpose of the junctional complexes

Release mature granules into the extracellular space

what do the mature granules that are released by the odontoblastic layer contain

GAGs, glycoproteins, collagen precursors which make up the basic components of the dentin matrix

What are the most numerous cells in the coronal pulp

Fibroblasts (cell rich zone)

What are fibroblasts

Spindle cells with an oval nucleus

Basophilic cytoplasm

Highly developed organelles involved in protein synthesis

What kind of cytoplasm do fibroblasts have

Basophilic

What type of cells are fibroblasts

Spindle cells

What precursors do fibroblasts in the pulp secrete

Collagen

Reticular fibers

Elastic fibers

What substance do fibroblasts in the pulp secete

Ground substance of the pulp

What is the function of the fibroblasts in the pulp

formation, Maintenance, Regulation Of extracellular matrix

Degrade collagen when needed

What is the top first layer of the odontoblasts in undifferentiated pulp

Odontoblastic zone

What is the second layer of the odontoblasts in undifferentiated pulp

Weil zone

What cells does the weil zone have

minimal cells but has some Höhl subodontoblastic, fibroblasts, nerve cells

What is weil zone referred to as

Cell free zone

What is the weil zone function

Space for odontoblats movement during dentin formation

What are Höhl subodontoblastic cells

Reserve mesenchymal cells

what 2 plexuses are found in the weil zone

Plexus of raschkow

Plexus of subodontoblastic capillaries

What is the third layer of the odontoblasts in undifferentiated pulp

Cell rich zone

What cells are in the cell rich zone

Macrophages, mesenchymal cells, fibroblasts, lymphocytes

What is the cell rich zone formed by

Ectomesenchymal cells

What is the cell rich zone function

Reserve cells for defense, repair and collagen production

Macrophage function

digest and remove foreigners

Use enzymes that facilitate migration within the connective tissue

APCs

What enzyme do the macrophages have to facilitate migration withiin the connective tissue

Acid hydrolase

What disease are the macrophages especially important in

Pulpitis

What do dendritic cells express

Class II molecules of the major histocompatibility complex

How are dendritic cells distributed In 2 areas

Perivascular region

Subodontoblastic region

Why are there dendritic cells in ther subodontoblastic region

To fight infections under the dentin and predentin

Why are there dendritic cells in the perivascular zone

To fight infections in the lymphatic system and blood vessels

What is the fourth/bottom layer of the odontoblasts in undifferentiated pulp

Pulp central zone

What cells are in the pulp central zone

Pericyes, vessels, endothelial cells

Function of the pulp central zone

Nutrition, waste removal, circulation