DENTAL PULP - lecture-notes.tiu.edu.iq

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DENTAL PULPPart Two

Dr. Hisham I. WaliM.Sc. Conservative

Nov/24/2019

Histology of the dental pulp

Principal cells of the dental pulp

Undifferentiated ectomesenchymal cells

They represent the pool from which connective

tissue cells of the pulp are derived.

These cells may give rise to odontoblasts and

fibroblasts depending on the stimulus.

They are present in the cell rich zone and pulp

core and often associated to blood vessels.

In older pulps the number of undifferentiated mesenchymal cells diminishes, along with the

number of other cells in the pulp core *

Dental pulp stem cells

These cells have a self-renewal capability

They can differentiate into odontoblasts, chondrocytes, adipocytes, and neurons

It has also been shown that these cells have the capacity to give rise to osteoblasts and

may therefore be a promising tool for bone regeneration.

Inflammatory cells

Macrophages tend to be located throughout

the pulp center

There are also some leukocytes (neutrophils and eosinophils) which increase substantially

during infection

Matrix & groundsubstance of dental pulp

The matrix of the pulp is composed of collagen

fibers type I and type III.

Collagen fibers are concentrated in the most

apical portion of the pulp*

This fact is of practical significance when a

pulpectomy is performed during the course of

endodontic treatment. 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,

where the pulp is more gelatinous and liable to

Functions of dental pulp

Inductive In early development the pulp (papilla) interacts with the oral epithelium and

initiates tooth formation.

Formative Odontoblasts of the pulp form the dentin that surrounds and protects pulp.

Protective Dental pulp is responsive to stimuli, such as heat, cold, pressure, and

operative cutting procedures. The formation of sclerotic dentin, the process of

mineral deposition in the tubules, originates in pulp and protects pulp from

invasion of bacteria and bacterial products.

It carries oxygen and nutrition to the developing and functioning tooth.Nutritive

Through its response to operative cutting or dental caries by the formation of

reparative dentin.

Reparative

Pulpal Irritants

Physical Irritants

Mechanical

Operative Procedures

Orthodontic Treatment

Biomechanical

Chemical Irritants

Iatrogenic Microbial

Pulpal Irritants

Operative procedures can adversely affect

pulpal integrity

Two main factors play an important role while

preforming operative procedures

The first one is the amount of heat generated

while cutting into tooth structure to prepare

the cavity

How to reduce or control the amount of

heat generated?

Operative procedures

Pulpal Irritants

The second factor is the

remaining dentin

thickness (RDT)

RDT is the thickness of dentin

covering dental pulp after

performing cavity preparation

Aspiration of odontoblasts due to

cutting dentin produce a more

permeable dentin that can facilitate

continued or future insult to the

subjacent pulp11

Pulpal Irritants

Biomechanical irritants

The final outcome of these irritants is called cusp flexure or

dentinal deformation

Cusp flexure may result from:

• Parafunctional habits: Bruxism, clenching, etc.

• Geometry of cavity preparation: Wide MOD cavity preparation

• Physical properties of some restorative material such as composite with detrimental

effects of polymerization shrinkage

❖ Cusp flexure or dentinal deformation irritate the pulp because it violates the dentinal

fluid (Hydrodynamic theory)

Mesio occluso distal Cavity (MOD) cavity

Clenching

Bruxism

Pulpal Irritants

Iatrogenic irritants

• From restorative material itself such as

unbound components of resin materials.

• From preparative agents such as acid

etchant, desiccation of dentin,

demineralization of dentin.

Microbial irritants

Most common cause for pulpal

irritation are bacteria or their

products which may enter pulp

through a break in dentin either

• Caries

• Accidental exposure

• Fracture

• Periodontal pocket and abscess

Pulpal Irritants

• Dental caries is the most common route for causing irritation to the pulp.

Dental caries is localized, progressive, decay of the teeth characterized by

demineralization of the tooth surface by organic acids, produced by

microorganisms.

• From the carious lesion, acids and other toxic substances penetrate

through the dentinal tubules to reach the pulp.

Pulpal Irritants

Microbial irritants

• The rate of reparative dentin formation is related to rate of carious

attack. More reparative dentin is formed in response to slow chronic

caries than acute caries.

• For dentin sclerosis to take place, vital odontoblasts must be present

within the tubules. In dentin sclerosis, the dentinal tubules are partially

or fully filled with mineral deposits, thus reduce the permeability of

dentin. Therefore, dentinal sclerosis act as a barrier for the ingress of

bacteria and their product.

Pulpal Irritants

Microbial irritants

Pulpal Irritants

Microbial irritants

The following defense reactions take place in a carious tooth to protect the pulp:

1. Formation of reparative dentin.

2. Dentinal sclerosis, i.e. reduction inpermeability of dentin by narrowing of dentinaltubules.

3. Inflammatory and immunological reactions.

Regressive changes of dental pulp

Pulp recession

Fibrous changes

Pulp stones

Diffuse calcification

Pulp recession

Decrease in the volume of the pulp

chamber and root canal brought

about by continued dentin

deposition.

Decreased pulp volume with age. The pulp

has been reduced considerably by the

continued deposition of dentin on the pulp

chamber floor 23

In old teeth the root canal is often

no more than a thin channel. The

root canal on occasion can appear

to be obliterated almost completely.

Pulp recession

Difference in pulp volume between a

young tooth (A) and an older tooth (B).24

Fibrous changes

Fibrosis is believed to be caused

more by injury than by aging.

In some cases, diffuse fibrosis with

collagen fibers appears throughout

the pulp. Occasionally, the fibers

nearly obliterate the pulp.

Pulp stones

Pulp stones, or denticles, frequently are

found in pulp tissue.

They are discrete calcified masses that have

similar composition to that of dentin.

They may be singular or multiple in any tooth

and are found in the pulp chamber or within the

root canal.

They are clinically significant since they may

act as impediment to debridement and

enlargement of the root canal system during

endodontic treatment.26

Diffuse calcification

Diffuse calcifications appear as irregular calcified

deposits along collagen fiber bundles or blood

vessels in the pulp.

This is considered a pathologic condition and

usually appears as a sprinkling of or occasionally

large masses of mineral.

These calcifications appear more often in the root

canal than in the coronal area of the pulp.

Effect of regressive changes of dental pulp on its function

Reduced sensitivity

Occurs as a result of pulp recession, deposition of reparative & sclerotic dentin which

increase the insulation of the pulp against various stimuli

Reduced repair potential

The number & activity of pulpal cells decline with aging

This in turn reduces the ability of pulp to repair itself after injuries & traumas

If injury occurred in young pulps, the differentiation of new odontoblasts from the

mesenchymal cells of the pulp and the formation of reparative dentin may take place. This

potential is reduced considerably with age.

Pulpitis refers to the inflammation of

the pulp that has not crossed the

periapical barrier and is limited to pulp.

Pulpitis is very painful and the

offending tooth will not be found tender

to percussion. And even some time

patient can not even differentiate

between the offending and the normal

tooth by himself. The reason behind this

is that pulp lacks the proprioceptive

nerve fibers, which are found in

periodontal ligaments.

Pulpitis

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