dental pulp - lecture-notes.tiu.edu.iq
TRANSCRIPT
DENTAL PULPPart Two
1
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 *
2
Histology of the dental pulp
Principal cells of the dental pulp
Dental pulp stem cells
These cells have a self-renewal capability
They can differentiate into odontoblasts, chondrocytes, adipocytes, and neurons
3
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.
Histology of the dental pulp
Principal cells of the dental pulp
Inflammatory cells
Macrophages tend to be located throughout
the pulp center
There are also some leukocytes (neutrophils and eosinophils) which increase substantially
during infection
4
Histology of the dental pulp
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*
5
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
tear.
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
6
Pulpal Irritants
Pulpal Irritants
Physical Irritants
Mechanical
Operative Procedures
Orthodontic Treatment
Biomechanical
Chemical Irritants
Iatrogenic Microbial
7
Pulpal Irritants
8
Pulpal Irritants
9
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
10
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
12
Pulpal Irritants
13
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)
14
15
Mesio occluso distal Cavity (MOD) cavity
Clenching
Bruxism
Pulpal Irritants
16
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.
17
Microbial irritants
Most common cause for pulpal
irritation are bacteria or their
products which may enter pulp
through a break in dentin either
from:
18
• 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
19
• 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
20
Pulpal Irritants
Microbial irritants
21
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
22
Regressive changes of dental pulp
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.
Regressive changes of dental pulp
Pulp recession
Difference in pulp volume between a
young tooth (A) and an older tooth (B).24
Regressive changes of dental pulp
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.
25
Regressive changes of dental 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
Regressive changes of dental pulp
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.
27
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.
28
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
29
30