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Dental Pulp

Slide 2:

Dental Pulp: is a specialized connective tissue. It is not only consists of nerves, but also blood vessels, ground substance, and etc.

Dental pulp is located within two places:

Crown – the part which present in the crown is called “Coronal Pulp” or “Pulp Chamber”.

Root – the part which present in the root is called “Radicular (جذري) Pulp” or “Root Canal”.

Normally, most of the cases each root has one root canal. But in some of the posterior teeth we may have two root canals. That means, the number of root canals is NOT necessary equal the number of roots.

Dental pulp forms as the reference of dental papilla. We said before that dental papilla forms dentin, and the remaining part of dental papilla after dentin has formed is called dental pulp. So, dental papilla becomes dental pulp after the begging of dentinogenesis. Y3nee once the dentinogenesis starts we no longer call it dental papilla, we call it dental pulp.

Dental pulp is a specialized connective tissue, because of:

It’s positioned inside a rigid chamber. So when there is an inflammation, it doesn’t have space for swelling. So, the swelling will compact the nerve, that’s why pain of pulpitis is one of the most sever pains.

Has a role in forming hard tissue. Because the periphery of dental pulp contain odontoblastic cells, these cells are important in hard tissue formation.

It periphery contain:i) Dentin-forming cells “odontoblats”.ii) Nerve terminals.iii) Antigen-presenting cells.

The rest of the pulp is a simple connective tissue acts as a support for the peripheral components. The most important part of the dental pulp is the peripheral components, and the central portion of the pulp act to support these peripheral components.

So, the blood vessels and nerves that enter and leave the core of the pulp are passing through the apical foramen. Beside that the core of dental pulp also contains cells and collagen fibers.

Slide 3:

We have also in addition to the main root canal that exist in the root we have Accessory Canals.

They occur most commonly on apical part of the tooth and they’re called:

Lateral Root Canal – when they communicate between the periodontal ligament and the main root canal.

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Furcation canals – they communicate between the pulp chamber and the main root canal.

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The composition of dental pulp:

Loose connective tissue and any connective tissue contain cells and extra cellular matrix. Cells and extra cellular matrix.

Cells – we’ll talk about them later. The extra cellular matrix- it’s composed of fibers and non-fibrous matrix (this non-fibrous is semi-fluid

gel). We can find the matrix is more plentiful than cells. This matrix forms a scaffold that stabilize the structure of the tissue, that’s why it’s a gel like material. Then, it also controls the cellular activity by acting as a medium for transmitting the signals between cells.

Slide 5:

Fibers of the dental pulp are collagen and fibrillin.

Collagen: Type I is the most predominant 56%. The fibers are:

Thin & scattered in young teeth. Irregular arrangement. Near predentine, fibers are regularly arranges parallel to predentine surface.

Type II 41%. Type V and VI but in small amounts.

Fibrillin: Large glycoproteins. Associated with elastic fibers in other tissue. Elastic fibers are absent.

Slide 6:

Glycosaminoglycans: Hydrophilic. Swell when hydrated accounting for:

- High pressure in the dental pulp.- Mechanical support.- Easy movement of water-soluble molecules.

Types – the Dr. said he won’t ask us about them ;) . Proteoglycans:

Act as adhesion molecules bound to cell membranes and bind signaling molecules like GFs.

Other adhesion molecules: Fibronectin - that regulates cell shape, migration & differentiation.

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Lamenin – located around endothelial cells of blood vessels & Schwann cells and it also coating the cell bodies and processes of odontoblasts.

Slide 7:

In the dental pulp there are four types of cells which are:

Odontoblasts Fibroblasts Defence cells Undifferentiated cells

Slide 8:

Odontoblasts:- It is responsible for the formation of dentin.- It will survive for as long as tooth is vital. That means the dentinogenesis is still continuous unless

when the tooth is extracted or the dental pulp is taken out.- Odntoblasts CAN’T divide but subodontoblasts can. That means once they differentiate and

become odontobalsts they can’t divide.- It is polarized columnar cells. So, the nucleus is NOT in the center, it’s away from dentin and

toward the pulp core. It also has a processes extending within the tubule (dentinal tubules).- It is columnar in crown and cuboidal in root.- Odntoblasts cell layer has:

i) A membrane-like properties acts as a barrier to protect the dental pulp from outside irritants (pathogens). ii) It also provide a limited permeability due to

Desmosomes. Tight junctions. Gap junctions.

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Fibriblasts:- Fibroblasts are linked together by adherence type junctions and gap junctions.- It is a stellate cell with star-like extensions and linked by junctions mentioned above.- It also undergo cell division- Functions:

i) Production of collagen fibers of the pulp and ground substance and participate in their degradation. ii) May produce bone-like mineralized tissue (pulp stone) as a response to pulpal injury.iii) Production of GFs and cytokines which are for development and resorb of the pulp.

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Slide 10:

Defence cells:- T-lymphocytes, initially in small amounts and increase in pulpal injuries.- Macrophages and antigen-presenting cells. They can be found around blood vessels and around

the odontoblastic layer (the most periphery part).- Mast cells are ABSENT. These cells produces histamine which is important for any tissues that

undergoing allergic reactions. So, pulp has NO allergic reactions.

Slide 11:

Undifferentiated cells:

It is primitive mesenchymal cells which are ready to differentiate into odontoblasts when we have high numbers of odontoblasts killed. So, the new odontoblasts are called tertiary dentine which also called irregular or reparative dentin.

Slide 12:

Blood Vessels:- Runs longitudinally through root canals from the apical foramina.- Then, it will give off side branches while within the canals. - It will branch profusely (many branches) once they reach the pulp chamber. So, the branching of

blood vessels is high in the coronal pulp and less in the radicular pulp.- The capillary loops extend towards the dentine (periphery of the pulp).- There is subodontoblastic capillary plexus. It the active area that supply nutrient to dentin.- Capillaries are present within and below the odontoblastic layer but do NOT enter the tubules. But

nerves DO extent the dentinal tubules.- Arteriovenous and venous-venous anastomosis can be found.- Lymphatic vessels are hard to distinguish in the dental pulp. But it still exist. - Nerve endings are associated with smooth muscles of arteriole walls. This is for the control of the

diameter of blood vessels.- Pulp has a high pulsatile interstitial fluid pressure which allows dentinal fluids to move outwards.

Slide 13:

The Dr. said you don’t have to worry about it ;) .

Slide 14:

The Dr. just went through the slide without mentioning any further information.

Nerves:- They run alongside the blood vessels in the center of the pulp.- Branch profusely in the odontoblastic & subodontoblastic regions.- In the crown, subodontoblastic plexus is known as plexus of Raschkow.- Evident only after eruption.

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- Some branches reach between odontoblasts & predentine.- Others continue & join the processes within the tubules.- May be a site of sensory activation as evident because axons lack Schwann cell covering.

Slide 15:

The Dr. said you don’t have to worry about this one, too ;) .

Slide 16:

Same as slide 14, he just went through the slide…

Nerve endings:- Some Aδ fibers enter the tubules in the coronal dentine.- Others end in predentine –pulp junction.- It is suggested that there is a specialized junction between nerve endings & odontoblasts.

Slide 17:

This slide is very IMPORTANAT!

Regions: Supraodontoblastic region:

- Not present in vital pulps.- Due to shrinkage of pulpal tissue during preparation.- Two structures are present:i) Unsheathed axons.ii) Dendritic antigen-presenting cells.

Odontoblastic layer. Subodontoblastic zone:

- Cell-free zone of Weil:i) No cells are evident.ii) Only axons & cell processes of fibroblasts & other cells.iii) Usually absent in radicular pulp.

- Cell-rich zone:i) Appears in contrast to cell-free zone.ii) Capillaries and nerve plexuses that contain the cell bodies of Schwann cells, endothelial

cells, etc. Central region:- The bulk of the dental pulp.- Central neurovascular core.- Fibroblasts, defence cells, undifferentiated cells.- Collagenous matrix and ground substance.

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Slide 18:

Age related changes:

With age the pulp gets smaller and there is a reduction in vascular, neural and cellular contents. It also increases in fibrous matrix due to decrease number of cells. It will also undergo some degree of mineralization. So, this will result in pulp stones and snow storm calcification. The pulp stones is either single or groups, True (dentine-like that may be lamellated) or False (bone-like), Free or attached to the dentin. While the snow storm calcification are tiny spicules throughout the pulp.

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Dentinal tubules

Odontobalstic Layer

Cell free zone of Weil

Subodontoblastic Layer

Cell – rich zone

Predentine

Central region

This picture shows many pulp stones (1, 2 & 3).

At the end the end I just wanna thank my dear friends ylle ma et3rafoo 3ali wla etla3o 3la geldet

weg-hee bss 3erfoo eni bdee afar8 mo7adra! Sari Abu Ghosh, Alaa Sultan and Maram Kakoush. wa kabel ma tefka3ee ya maram, I know you have no idea about the tafree8, bss you’re as guilty as them because you didn’t AKS!! Wlw akl ma feeha el wa7ad bs2l ! :P

Good luck all =D

Done by: Saleh Razick.

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