Dentin

Guided By -
Dr.Vandana Kokane
Dr. Pratima Shenoi
Dr. Rajesh Kubde
Dr. Chetana Makade
Dr. Gautam Badole
Presented by:-
Dr. Himani Thawale

 Introduction
History
 Properties
 Structure
Types of dentin
Deveplopmental defects
Clinical consideration
CONTENT

The tooth proper consists of
the less mineralized, more
resilient and vital hard
connective tissue called
DENTIN
Orban’s oral histology and embryology 13th edition
Provides the bulk and
general form of tooth
 It is characterized as a hard
tissue with tubules throughout
its thickness

It determines the shape of the crown , including the cups
and ridges ,and the number and size of the roots.
Physically & chemically the dentin closely resembles the
bone.

TOOTH
ECTOMESENCHYME
DENTAL
FOLLICLE
DENTAL
PAIPILLA
ECTODERM
ENAMEL
ORGAN
Development of tooth

Low columnar cells
Polygonal cells
Enamel organ
Dental papilla

Outer enamel epithelium
Stellate reticulum
Inner enamel epithelium
Dental pailla
Dental follicle

Charactrized by start of mineralization
and root formation.
Formation of DENTINOENAMEL
JUNCTION
Formation of dentin occurs first
along this DEJ.
After first layer of dentin is
formed , amelobast lay down
enamel.

DENTINOGENESIS mainly involes:-
FORMATION OF MANTLE DENTIN
FORMATION OF CIRCUMPULPAL DENTIN
MINERALIZATION
FORMATION OF ROOT DENTIN
ODONTOBLAST DIFFERENTIATION

INDUCTION
• Epithelial cells are inductive
• secrete growth factors (TGF-B1
, BMP2, IGF)
• Binds to herpan sulfate found in
basal lamina
• Transferring inductive ability to
basal lamina
COMPETANCE
• Ectomesenchymal cells
assumes competance following
a set number of cell divisions
• After which they express cell
surface recpetors
• These receptors capture the
growth factors now localised to
basal lamina

Once the odontoblast differentiate , they enter a life cycle
related to formation ,maintainance and repair of dentin.
The various stages of odontoblast are:-
Secretory stage
Resting stage
Transitional stage

 Consist of
-Type 1 collagen
-Ground substance
ORGANIC MATRIX
 First collagen of dentin appears:-
- Extracellularly
- Very distinct large diameter fibrils
Von Korff’s fibers
These large collagen fibers along with the ground substance
constitutes the organic matrix of First formed or Mantle dentin.

18
Hydroxyapatite first appear
within the matrix vesicles as
single crystal
These crystals grow rapidly &
rupture from the confines of
vesicle
The deposition of mineral tags
behind organic matrix , so that
there is always a layer of organic
matrix PREDENTIN
INORGANIC MATRIX

.
first
• Increase size of odontoblast and organic matrix is now
formed exclusively from odontoblast
second
• Aggregation of collagen as much smaller fibrils,
which are more closely packed and interwoven
Third-
• Absence of matrix vesicles
Finally
• Addition of further components to organic matrix e.g.
Lipids, phosphoprotein , phospholipid

Throughout dentinogenesis, mineralization is
acheived by continous deposition of mineral,
initially in the matrix vesicle and then at
mineralization front

• Globular Pattern- Deposition of
crystals in several discrete areas
of matrix, these globular mass
continue to enlarge and fuse to
form single calcified mass.
• Linear Pattern- When the rate of
formation progress slowly, the
mineralisation front becomes
more linear and uniform.

Hertwig’s epithelial root
sheath intiate root dentin
formation.
• Less phosphoryn content.
Degree of mineralization
slightly less.

PHYSICAL PROPERTIES
It is light yellowish in color.
It is viscoelastic and subject to
slight deformation.
Harder than bone but softer
than enamel.
It is more radiolucent than
enamel

Compressive strength -
266MPa(40,000PSI)
Tensile strength- 40MPa (6000 PSI)
Modulus of elasticity- 18.5 GPa
Oral Anatomy,histology And Embryology : Berkovitz

By weight By volume
Chemical composition
ORGANIC
20%
WATER
10%
INORGANI
C
70%
ORGANIC
33%
WATER
22%
INORGANI
C
45%

ORGANIC
MATTER
Collagen
Type1 collagen
Non
collagenous
matrix protiens

• Chondroitin sulphate
• Decorin
• Biglycan
Proteoglycans
• Dentin sialoprotein(DSP)
• Osteonectin
• Osteopontin
Glycoproteins
• Dentin
phosphoproteins(DPP)
• Gla-proteins
• Phospholipids
Phosphoprotein

Calcium hydroxyapatite :
CA10(PO4)6(OH)2
Thin plate like crystals , shorter than
enamel.
Salts – calcium carbonate , sulphate ,
phosphate.
The crystals are poor in calcium but
rich in carbon compared to enamel

Primary dentin
1. Mantle dentin
2. circumpulpal dentin
Secondary dentin
Tertiary dentin
1. Reactionary dentin
2. Reparative dentin

• First formed dentin underlying the
DEJ.
•It is soft and provides cushioning
effect to tooth.
•The fibrils formed in this zone are
Von Korff’s fibers.
•Undergoes globular mineralization

Remaining bulk of primary dentin.
Collagen fibrils are much smaller
in diameter (0.05 µm)
The mineralization pattern is
globular or linear for
circumpulpal dentin.

formed after root completion.
A narrow band of dentin bordering
the pulp
It is formed in response to external
stimuli
Clinical significance:- Protect the
pulp from exposure in older teeth.

Also called as reparative , response, or reactive dentin.
It is formed in response to stimuli
- Attrition
-Abrasion
- Erosion
- Cavity preparation
Clinical significance:-
It is deposited at specific site in
response to injury

The bodies of the odontoblasts are arranged in a layer
on the pulpal surface of the dentin, and only their
cytoplasmic processes are included in the tubules in the
mineralized matrix.

Each cell gives rise to one process, which traverses the
predentin & calcified dentin within one tubule

The course follows a gentle curve in the crown, less so in
the root, where it resembles S in shape.

Canaliculi:-
The dentinal tubules have
lateral branches throughout
dentin, which are termed
canaliculi or microtubules.
Enamel spindle:-
A few dentinal tubules extend
through the dentinoenamel
junction into the enamel. These
are termed enamel spindles.

 Dentin permeability depends upon total surface area of exposed dentin.
 Bacterial and their toxin products are the most significant to travel
down the tubules.
 Heat or air desiccation eliminates fluid from tubules and thus increases
the dentin permeability.
 The tubular structure of dentin also provides for rapid spread of dental
caries.

 Originally, the peritubular dentin is dentin
immediately surrounds the dentinal tubules.
 It is 44nm wide near the pulp and 750nm
wide near the dentinoenamel junction
Rich in glycosaminoglycans termed Lamina
limitans.

 Main body of dentin.
 Location:- between the zones of
peritubular dentin.
 Its organic matrix is retained after
decalcification.
About one-half of its volume is organic
matrix, specifically collagen fibers 0.2 to
0.5um diameter

 Location:- adjacent to the pulp tissue.
 Is 2 to 6 um wide.
 First formed dentin and
is not mineralized.



Small globular areas that fail to
fuse into a homogeneous mass
called interglobular dentin.
The dentinal tubules pass
uninterruptedly, demonstrating
a defect of mineralization
& not of matrix formation.
Occurs more in cervical and middle
third of crown

 In dry ground section of root dentin, a zone adjacent to the cementum appears
granular in transmitted light.

• It increases in amount from the CEJ to the
root apex
• Caused due to coalescing and looping of
terminal portions of dentinal tubules.
• High amount of calcium and phosphorus.
• Recent studies relate it as a special
arrangement of collagen and non
collagenous matrix proteins at the interface
between dentin and cementum.

The incremental lines of von ebner, or imbrication lines,
appear as fine lines or striations in dentin.
 Accentuated incremental lines because of disturbances in
matrix and mineralization process are termed as Contour
Lines of Owen.

• In decidous teeth and first permanent molars the prenatal and
postnatal dentin are seperated by accentuated incremental
line termed as ‘Neonatal line’.

• Scalloped line.
• The convexities of scallops are
directed towards dentin.
• More pronounced in occlusal
area where masticatory stresses
are greater.

• Smooth in outline.
• In deciduous teeth it may be
scalloped.
• The DCJ is a wide zone
containing large quantities of
collagen along with chondroitin
sulphate and dermatan sulphate.

• Nerve fibers accompany 30 to
70% of odontoblastic processes
-intratubular nerves.
They are terminal processes of
the myelinated nerve fibers of
the dental pulp.
Synapse like relation between
the process and nerve fibers
were demonstrated

Various age and functional changes are:-
1) Reparative dentin
2) Dead tracts
3) Sclerotic dentin

o Also known as tertiary or response dentin.
o Has fewer & more twisted tubules than normal
dentin.
o Sometimes, a combination of osteodentin &
tubular dentin is seen
o Odontoblasts lay down at a rate of 4 um/day

In dry ground section, the odontoblast process
disintegrate and the empty tubules get filled with air.

 Found specially in roots.
 Transparent or light in transmitted and dark in reflected
light.

• In cases of stimuli such as caries , attrition causes
growth of collagen and apatite crystals begin appearing
in the dentinal tubules
• Apatite crystals are initially only sporadic in a dentinal
tubule but gradually fill it with a fine meshwork of
crystals.
• Gradually, the tubule lumen is obliterated with
mineral, which appears very much like the peritubular
dentin

Dentinogenisis imperfecta
Dentin dysplasia
Regional odontodysplasia
Dentin hypocalcification

• Autosomal dominant condition.
• Teeth appears Gray to yellowish brown.
• Broad crowns with constriction of cervical area results in
TULIP shape.
• Enamel is easily broken and leads to exposure of dentin.

Opalescent dentin,Capdepont
teeth,Shields type II.
Due to mutation in DSPP gene
mapping to chromosome 4.
Blue, gray or amber brown and
opalescent teeth.

 Shield’s type III, Brandywine type DI.
Dentin is amber coloured and smooth.
Classic SHELL teeth are seen.

Bulbous crown, roots narrower ,pulp chambers
and canal smaller or completely obliterated.
 Presence of ‘shell teeth’.

Dentin is composed of irregular tubules often with large
areas of uncalcified dentin.
Tubules are large in diameter in some areas & may also
be absent.
Pulp chamber is obliterated due to dentin deposition.

Directed primarily towards prevention of loss of
enamel and dentin by attrition.
Cast metal crowns on posteriors,
Jacket crowns on anterior teeth.
Restorations are not usually permanent because of
softness of dentin.

Normal enamel but atypical dentin formation and abnormal
pulpal morphology.
Radiographically, extremely short roots and obliteration of
pulp chambers and root canals

 Radiographically:-
In deciduous teeth pulp chamber
and canals are
obliteratedwhile,crescent shaped
pulpal remnant seen in permanent
dentition.
Histologically:-
New dentin forms is Lava
flowing around the boulders.

Radiographically, deciduous
dentition shows obliteration of pulp
chambers while, permanent teeth
shows ‘Thistle tube’ appearance.
Histologically, atubular dentin in
deciduous teeth and numerous pulp
stones are seen in permanent teeth.

Maxillary teeth involved more
frequently.
Teeth are irregular in
appearance and shape is altered
markedly.
Evidence of defective
mineralization.

It shows marked reduction in radiodensity of teeth.
This is called as ‘Ghost’ appearance.
Enamel and dentin appear very thin and pulp chamber is
exceedingly large.

There is marked reduction in amount of dentin.
Widening of predentin layer
Presence of large areas of interglobular dentin and
irregular tubular pattern of dentin
Treatment: involves extraction and prosthetic
replacement.

Normal dentin is calcified by deposition of calcium salts in
the organic matrix in the form of globules.
In dentinal Hypocalcification there is failure of union in these
globules.

Caries in dentin begins with natural
spread of disease process along DEJ
and rapid involvement of large number
of dentinal tubules.
Which acts as pathway for micro-
organisms leading to dental pulp.
Dentinal caries advances more rapidly
in dentin than in enamel.

• Non bacterial, pre cavitational, Acid softening of
enamel
• Migration of pioneer bacteria along the tubules
• Breakdown of intervening matrix forming
liquefication foci
• Progressive disintegration of remainig matrix
tissue

• Deposition of fat globules
• Fat contributes to impermeability
ZONE1
• Deposition of calcium salts in tubules
• Appears white in transmitted light
ZONE 2
• Above the dentinal sclerosis
• Ocurs in advance of bacterial inavasionZONE 3
• Acidogenic organism in early caries
• Proteolytic organism in deeper layer
ZONE 4
• Necrotic mass of dentin of leathery
consistencyZONE 5
Zones of dentinal caries

Infected dentin Affected dentin
Outer carious dentin
soft and leathery in
consistency
Inner carious dentin
hard in consistency
dark brown in color. light brown in color.
high concentration of
bacteria
does not contain bacteria
collagen is irreversibly
denatured
Collagen is reversibly
denatured
not remineralised and
must be removed.
Can be remineralised and
therefore should
preserved
Infected and affected dentin

DEFINATION:-
It is defined as short , sharp pain arising from exposed
dentin in response to stimuli typically thermal,
chemical, tactile or osmotic and which cannot be
ascribed to any form of dental defect or pathology.

Direct Innervation theory
-Neural theory
-according to this theory , direct mechanical
stimulation of exposed nerve endings at DEJ is
responsible for dentin hypersensitivity.
Odontoblast Receptor theory
- tranduction theory
- it proposes that odontoblast itself act as neural
receptors and relay the signal to the nerve terminal

Dentinal tubules which are open and wide contains
fluid
Various stimuli displaces this fluid in either an
inwardly or outwardly direction
Movement of this liquid stimulates the odontoblastic
process
Subsequent mechanical disturbances stimulates
baroreceptors
Leads to neural discharge

ATTRITION ABRASION ABFRACTION
DENUDATION OF
CEMENTUM
GINGIVAL
RECESSION
EROSION

 PAIN is the most common clinical feature
Most commonly involved teeth are
i) buccal surface of premolars
ii) facial surface of insciors
External stimuli which elict the expression of this condition
include:
i)thermal stimuli ii)osmotic stimuli
- hot/ cold beverages - sweet food
iii) acidic stimuli iv) mechanical stimuli
- citrus fruits - toothbrush

Removal of Etiological factors
Patient education
Treatmant strategies include:-
i) Desensitizing the nerve
- Potassium nitrate
ii) Occluding the dentinal tubules
- 0.4% stannous flouride
- 2% sodium flouride
- potassium oxalate
- CPP-ACP complex

iii) Dental adhesives
- DFluoride varnishes
- Oxalic acid and resin
-Dentin bonding agents
- Glass ionomer cements
- Composite resins
iv) Crown placement
v) Periodontal grafting

vi) Lasers
- CO2 lasers
- Nd : YAG, Er: YAG lasers
Use of anti-inflammatory agents which induce
mineralization leading tubule occlusion
Symptom still persist- Root canal treatment / extraction.

 The concept of dentistry with the introduction of adhesives has changed
from - Extension for Prevention to PREVENTION OF EXTENSION !!!
 Adhesion of restorative materials to enamel has become a routine and
reliable aspect of modern restorative dentistry
 But adhesion to dentin has proved to be more difficult and less predictable.
 Much of the difficulty in bonding to dentin is the result of the complex
microstructure and variable composition of dentin in different areas of the
tooth.

 The presence of water and organic components lower the surface energy
of dentin and make bonding with hydrophobic resins essentially
impossible
 Dentin is an intrinsically hydrated tissue, penetrated by a maze of 1- to
0.25-μm-diameter fluid-filled dentin tubules.
 Dentin close to the pulp shows a higher tubule density than in dentin
remote from the pulp. The higher the tubule density, the lower the bond
strength values of the dentin adhesives

 Bonding agents can be defined as material of low viscosity, when applied
on the tooth surface forms thin film after setting.
 This thin film strongly bonded to tooth surface, on which the viscous
composite restorative resin is applied. This sets forming an integrated resin
restoration.

FIRST GENERATIONS
 NPG-GMA, was the of first commercially available dentin bonding agent.
 ADHESION TO SMEAR LAYER
SECOND GENERATION:-
 Introduced in 1970s and bonded chemically to either inorganic or organic
components of dentin
 But they produced only limited bond strength
(5-6 mpa)
 Examples:-
 Clear fill bonds system F
 scotch bond
 bond lite.

THIRD GENERATION
 Third generation attempted to deal with smear layer and
dentinal fluid
They employed two approaches:-
 Modification of smear layer to improve its property
Or
 Removal of smear layer without disturbing smear plugs
that occlude the dentinal tubules.
 The idea was to avoid aggressive
etching of dentin because it cause
pulpitis
Eg:- Tenure, Scotch bond2

Water acts as plasticizer for collagen and keeps it in a
soft state
If dentin is excessively dried it will lead to collapse of
collagen network
Critical amount of water is essential for bonding,
that prevents the collapse of collagen network
and allow expansion of dried dentin
 An over wet dentin decreases the bond strength
and formation of blister like structure at the interface.

Most new adhesives utilize the
‘wet bonding technique’.
The ‘wet bonding’ has repeatedly shown enhanced bond
strengths as water preserves the porosity of collagen
network available for monomer interdiffusion.

whenever tooth structure is prepared with a bur or other
instrument, residual organic and inorganic components form
a layer of debris on the surface of the substrate
 Smear layer fills the orifices of dentin tubules and form
smear plugs and decreases dentin permeability by nearly
90%

 Thickness of smear layer : 0.5-2 μm
 Thickness of smear plug : 1-10μm
COMPOSITION:-
Iatrogenically produced smear layer is predominantly
made of hydroxyapatite and altered denatured collagen.
Altered collagen acquire gelatinised consistency due to
friction and heat

CLINICAL CONSIDERATIONS
 The presence of intact smear layer is detrimental for bonding
OPTIMAL DENTIN BONDING can take place
by:
 a) Complete removal of smear layer prior to the bonding
procedure by using etch and rinse adhesive
 b) Incorporation of smear layer into bonding layer by using self
etch adhesives.

Composite resin restorations
Early bonding agents were hydrophobic and were bonded
directly to dentin smear layer- Bond strength
unsatisfactory.
Newer bonding system leads to:-
a) Complete removal of smear layer prior to the
bonding procedure by using etch and rinse adhesive
b) Incorporation of smear layer into bonding layer
by using self etch adhesives.

Amalgam restorations
o Dentin smear layer are left in place for unbonded amlagam
restorations
o It produces some degree of dentinal tubule sealing ,
although it is 25 % to 30% porous
o Halving the diameter of the opening produces a sixteen fold
reduction in flow.
o Therefore the smear layer is very effective barrier.

ADVANTAGES :-
 Reduction of dentin permability to toxins and oral fluids
 Reduction of diffusion of fluid and prevents wetness of cut
dentin surface
 Bacterial penetration of dentinal fluid is prevented.

It may harbour bacteria, either from original carious lesion
or saliva, which may multiply taking nourishmaent from
smear layer or dentinal fluid.
Smear layer is permeable to bacterial toxins
Smear layer itself is infected(Presence of bacteria)
It blocks antimicrobial effect of intracanal medications and
increases disinfecting tissue.

Presence of smear layer would necessitate use of higher
concentration and/ or amount of anti bacterial agents.
Act as a intermediate physical barrier, interfere with
adhesive penetration of sealers(obturating material)
with dentinal tubules
Studies have shown better adhesion of obturation
materials to the canal walls after removal of smear
layer.

CALCIUM HYDROXIDE
Herman (1930) – Ca(OH)2 pulp
capping
 The greatest benefit of Ca(OH)2 is
the stimulation of reparative dentin
bridge formation.
Ex:- Pulpdent paste & Dycal

Biodentine is a new generation material based on calcium
silicate synthesized by bioactive technology
 Biodentine stimulates release of TGF-β from pulpal cells,
stimulating reparative dentin formation in a very short period
of time.

COMPOSITE Shrinkage during polymerization may
induce internal stresses on dentin and create voids that
may lead to cuspal fracture and microleakage

Type of restoration Shallow RDT
>2mm
Moderately
deep
RDT(>0.5-
2mm)
Deep RDT
<0.5mm
Silver
amalgam
varnish Base –e.g. zinc
phosphate , zinc
polycarboxylate
Calcium
hydroxide (sub
base) with base
Glass ionomer cement Not required Not required Calcium
hydroxide as
liner
Composite resin Dentin bonding
agent
Dentin bonding
agent
Calcium
hydroxide as
liner followed by
GIC as base
Cast restoration Base Calcium
hydroxide as
liner with base
over it

It is known that if 1mm.sq. of dentin is exposed 30,000
living cells are damaged.
So, it is advisable to seal exposed dentin surface with
non-irritating and insulating materials.
Preparation with rotary instruments is likely to injure
the odontoblastic layer.
Owing to dehydration of the tubular content,
odontoblasts may even be sucked into the
dentinal tubules.

Heat produced during deep cavity preparation causes loss
of odontoblasts or their aspiration into the dentinal
tubules. Thus, a coolant should be used while cutting
dentin.
Dessication during cavity preparation has long been
known to cause aspiration of odontoblastic nuclei into
dentinal tubules.

Periodontal diseases cause attachment loss exposing the
root surface to the oral cavity which may lead to
dentinal hypersensitivity.

If tetracycline is given in the period of pregnancy
or during the development of tooth, Then stains
are likely to be developed in the line related to
the dentinal curvature.

 Ten cate oral histology (development structure and function)- 5th edition.
 Orban’s oral histology and embryology- 13th edition.
 Oral anatomy,histology and embryology : berkovitz.
 Shafer’s textbook of oral pathology- 7th edition.
 Sturdevent’s art & science of operative dentistry- 5th edition.
 Grossman – 13th edition
 Cohen pathology of the pulp 10th edition.

Dentin

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