Dentin development

Guided by:
Dr.Arundeep Singh
Head of the department
Department of Conservative
Dentistry and Endodontics
Presented by:
Mohana Pratima.k
Post graduate 1st year

• Definition.
• Stages of tooth deveopment.
• Dentinogenesis and mineralization.
• Physical and chemical composition.
• Types of dentin.
• Theories of pain transmission.
• Age and functional changes of dentin.
• Clinical considerations.
Dentinal carious zones
Dentinal Hypersensitivity
Dentin Bonding Agents
Dentinogenesis Imperfecta
Dentin Dysplasia
Dens Evaginatus

Def:
• A calcareous material similar to bone but harder and
denser that composes the principal mass of a tooth, is
formed by the odontoblasts of the surface of the
dental papilla, and consists of a matrix containing
minute parallel tubules which open into the pulp
cavity and during life contain processes of the cells of
the pulp - Merriam Webster
• The formation of dentin, known as dentinogenesis
begins prior to the formation of enamel and is initiated
by the odontoblasts of the pulp.
• Unlike enamel, dentin continues to form throughout
life and can be initiated in response to stimuli, such
as tooth decay or attrition.

Early bell stage Advanced bell stage
Cervical loop

Dentinogenesis:
• Begins at the cusp tip after odontoblasts have
differentiated and begin collagen production
• In odontoblasts differentiation, fibronectin, decorin,
laminin, chondroiton sulfate may be involved.
• Laminin alpha 2, subunit of laminin is essential for
odontoblastic differentiation and to regulate the
expression of dentin matrix proteins.
• Factors like TGF, IGF, BMP help in organisation of
odontoblast important for relocation of organelles.
Orbans histology and embryology

• One of the key proteins involved in mineralization and
secreted by the odontoblast is the Dentin
phosphoprotein(DPP).
• Binds to calcium, transports it to the mineralization front
and controls the growth of apatite crystals.
• Osteonectin: inhibits growth of apatite crystals, but
promotes binding in collagen.
• Osteopontin: a phosphoprotein, promotes mineralization.
• Gla protein: acts as seeds or nucleators to attract and
concentrate calcium.
• Matrix vesicles are also involved in mineralization of mantle
dentin.

• Initially daily increments of approximately 4um of
dentin are formed.
• This continuous until the crown is formed and the
teeth erupt and move into occlusion.
• Dentinogenesis is a two-phase sequence in that
collagen matrix is first formed and then calcified.
• Kroff’s fibers described the initial dentin deposition
along the cusp tips.
• Radicular dentin formation is slower when compared
to coronal dentin, less mineralized with collagen
fibers laid down parllel to CEJ.

Mineralization:
• Earliest crystal deposition is in form of very fine
plates of hydroxyapatite on the surfaces of the
collagen fibrils and in the ground substances.
• The apatite crystals found in dentin resemble those
found in bone and cementum.

Provides the bulk and general
form of tooth.
Determines the shape of the
crown.
Physically & chemically the
dentin closely resembles the
bone.
The main morphologic difference
between bone & dentin is that
some of the osteoblasts that form
bone marrow enclosed within its
matrix substance as osteocytes,
whereas the dentin contains only
the processes of the cells that
form it.

Physical and chemical properties.
Physical properties:
• Teeth of young individuals- light yellowish in color,
darkens with age.
• Dentin is slight viscoelastic and is subjected to slight
deformation.
• Harder than bone but softer than enamel.
• Dentin of primary teeth is less hard then permenant
teeth.
Chemical properties:
• The lower content of mineral salts render it more
radiolucent than enamel. It consistes of 35% of organic
matter, water and 65% inorganic matter.
Both are considered vital tissue because they contain
because they contain living protoplasm.

Inorganic component:
• Collagenous fibrils.
• TypeI collagen is
principal type of collagen
found in dentine.
• The protein of dentin
matrix and bone are
similar , but dentin
sialoprotein and dentin
phosphoprotein are
present only in dentin.
• Matrix also contains
growth factors like TGF,
FGF, IGF-s, BMP-s.
• Matrix also plays an
important role in dentin
mineralization.
• Hydroxyapatite.
•Also contains small
amounts of phosphates,
carbonates, sulfates.
• Organic and inorganic are
substances can be
seperated by either
decalcification or
inceneration
Organic substances:

Structure
• Tubules are found throughout normal dentin and are
therefore its charectestic
Dentinal tubules:
• The course of dentinal tubules follows a gentle curve
in the crown, so less in the root where it resembles
gentle S shape.
• These curvature are called primary curvatures.
• Branches of the dentinal tubules near the terminals
are referred to as terminal branches.
• Over the entire lengths the tubules exhibit the
minute, relatively Secondary curvature that are
sinusoidal in shape

DEJ
Terminal branches
Odontoblastic process

• The dentinal tubules have lateral branches
throughout dentin, which are termed Canaliculi or
microtubules.
• A few dentinal tubules extend through the
dentinoenamel junction into the enamel for several
millimeters termed as enamel spindles.

Peritubular dentin:
• The dentin that surrounds immediately the dentinal
tubules is termed as peritubular dentin.
• This dentin forms the walls of the tubules in all but
the dentin near the pulp.
• Highly mineralized then the dentin present between
tubules.
• Since the deposition occurs in the inner wall of the
tubule rather then the outer wall, is called
“intratubular dentin”.
• The calcified tubules wall has inner organic lining
termed the lamina limitans.
• Between the odontoblastic process and the peritubular
dentine, a space known as periodontoblastic space.
• This space contains dentinal fluid.

Peritubulardentin
(Neumannsheath)

Periodontoblastic space
Odontoblastic process(tomes fibers)
Dentinal tubules

Intertubular dentin:
• The main body of dentine is composed of intertubular
dentin.
• Although it is highly mineralized, this matrix, like bone
and cementum, is retained after decalcification.
Predentin:
• Located always adjacent to pulp tissue and is 2 to 6
um wide, depending on the extent of activity of
odontoblast.
• Not mineralized.
• As the collagen fibers undergo mineralization at the
predentin-dentin junction, the predentin becomes
dentin and a new layer of predentin forms
cicumpulpally.

Odontoblastic process:
• Are the cytoplasmic extensions of the odontoblasts.
• The odontoblast cells reside in the peripheral pulp at
the pulp-dentin border and their process extend into
dentinal tubules.
• The process are larger in diameter near the pulp and
taper further into dentin.
• The odontoblast process divide near the DEJ and may
extend into the enamel in the enamel spindles.

dentin
Odontoblastprocess
predentin

Types of dentine:
Primary dentin
Mantle dentin :
• The name of the first-formed dentine in crown underlying
DEJ.
• Below DEJ is soft and provides cushioning effect to the
tooth.
• The fibrils are perpendicular to DEJ and organic matrix
composed of large collagen fibrils.
• The larger diameter collagen fibers are argyrophilic and
are known as von Kroff’s fibers.
• They contain mainly type III collagen.
Circumpulpal dentin:
• Forms the remaining primary dentin or bulk of the tooth.
• Dentin that represents all the dentin formed before root
completion.
• May conatin slightly more mineral than mantle dentin.

Enamel
Mantle dentin
Circumpulpal dentin
Irregular secondary
(tertiary) dentin
regular secondary dentin

Mantel dentin
circumpulpal dentin

pulp
pulp
Odontoblast layer
predentin
Circumpulpal dentin

Secondary dentin:
• Is a narrow band of dentin
bordering the pulp and
representing that dentin formed
after root completion.
• This dentin contains fewer
tubules than primary dentin.
• Not formed uniformly and
appears in greater amounts on
the roof and floor of the coronal
chamber, where it protects the
pulp from exposure in older
teeth.
• Due to regular arrangement of
dentinal tubules it is known as
regular secondary dentin.

An accentuated calcio-traumatic band under the
cavity represents an acute arrest in
odontoblastic activity as a result of the operative
procedure

Tertiary dentin:
• It is reparative, response or reactive dentin.
• This is localized formation of dentin on the pulp-
dentin border, formed in reaction to trauma such as
caries or restorative procedures

Incremental lines:
• Appears as fine lines or striations in dentin.
• These lines represent the daily rhythmic recurrent
deposition of dentin matrix as well as a hesitation in
the daily formative process.
• The course of lines indicates the growth pattern of
the dentin.
• Incremental lines are accentuated because of
disturbances in the matrix and mineralization
process called contour lines(Owen)

• In deciduous teeth and in 1st permanent molars,
where dentin is partly before and partly after birth,
the prenatal and postnatal dentin are separated by
an accentuated contour line termed as neonatal
line seen in enamel and dentin.

Interglobular dentin
• Sometimes mineralization of dentin begins in
small globular areas that fail to coalesce into
homogenous mass. Results in zones of
hypomineralization between the globules.
• These zones are called globular dentin or
interglobular space.

Granular layer:
• When dry ground sections of the root dentin are
visualized in transmitted light, a zone adjacent to
cementum appears granular known as tomes’
granular layer.
• This areas remain unmineralized like interglobular
dentin.
• Though Tomes granular layer and interglobular
dentin have similarities in formation but differ in
mineral content.
• Tomes granular shows high calcium and
phosphorous , while interglobular dentin showed
higher content of sulfur.

Granular layer of Tomes
Dentin (with tubules)
cementum

Granular Layer of Tomes
dentin
cementum
enamel

Innervation of dentin:
• Nerve fibers shown to accompany 30% to 70% of
odontoblastic process and these after referred to as
intertubular nerve.
• Synapse like relation between the process and nerve
fibers were demonstrated.
• These are the terminal process of myelinated nerve
fibers if the dental pulp.

Direct
Neural
Stimulation
•Which the nerves in dentin get stimulated.
•The nerves in the dentinal tubules are not commanly seen
and even present they do not extend beyond the inner
dentin.
Hydrodynamic
theory
•This fluid movement, either inward or outward stimulates
pain mechanism in the tubules by the mechanical
disturbances of the nerves closely associated with the
odontoblasts and its process.
•These endings may act as mechanoreceptors.
Transduction
theory
•Presumes that odontoblast process is the primary structure
excited by the stimulus and that impulse is transmitted to
the nerve endings in the inner dentin.
•No neurotransmitter vesicles in the odontoblast process to
facilitate the synapse or synaptic specialization.

Permeability of dentin
• Depends upon the patency of dentinal tubules.
• Tubular occlusion, smear layer formation and lack of
tubular communication between primary and
irregular secondary dentin will result and reduce the
permeability.
• Reduction in dentin permeability would lessen the
sensitivity of dentin.

Age and functional changes
Vitality of dentin:
• Dentin is laid down throughout the life although the
teeth are erupted and functioning for a short time,
dentinogenesis slows and further dentin formation is
at much slow rate.
• Pathologic effects of dental caries abrasion, attrition,
or cutting of dentin of operative procedures cause
changes in dentin. They are described as development
of dead tracts, sclerosis and the addition of reparative
dentin

Reparative dentin:
• If by extensive abrasion, erosion, caries or operative
procedures the odontoblastic process are exposed or
cut, the odontoblasts die or survive.
• If they survive the dentin that is produced is called
reactionary or regenerated dentin.
• Origin of new odontoblasts is from cells of cell rich
zone .
• The irregular nature of dentinal tubules, these types
of dentin are referred as irregular secondary dentin.
• It is believed that bacteria, living or dead or their toxic
products as well as chemical substances from
restorative materials migrate down the tubules to the
pulp and stimulate pulpal response leading to
reparative dentin formation

Dead tracts:
• In dried ground sections of normal dentin the
odontoblasts process disintegrate, and the empty
tubules are filled with air.
• They appear black in transmitted light and white in
reflected light.
• Where reparative dentin seals dentinal tubules at their
pulpal ends are filled with fluid or gaseous substances.
• These areas demonstrate decreased sensitivity and
appear to a greater extent in older teeth.
• These dead tracts are probably the initial step in the
formation of sclerotic dentin.

Sclerotic dentin:
• Also transparent dentin.
• Stimuli not only induce additional
formation of reparative dentin but
also, lead to protective changes in
the existing dentin.
• The refractive indices of dentin in
which tubules occluded are
equalized, and such areas become
transparent.
• Seen mostly in elderly people
especially in roots. And also in
slow progression caries.
• Mineral density is greater in this
area of dentin.
• Sclerotic dentin was harder than
normal dentin, its fracture
toughness reduced.
• Tranparent - transmitted light
• Dark- reflected light.
Indicates location of dentin
sclerosis

Zones of dentinal carious lesion
Normal dentin:
Deepest zone of carious dentin is normal with normal
collagen, odontoblastic process and intertubular
dentin.
Subtransparent dentin:
Intertubular dentin is demineralized, odontoblastic
process are damaged. But no bacteria is found.
Transparent dentin:
Superficial to subtransparent. Softer than normal dentin.
No bacteria so this layer is capable of remineralization.
Turbid zone:
Dentinal tubules are widened and distorted by bacterial
penetration. Incapable of remineralization and must be
removed before restoration.
Operative dentistry-ramya raghu

Infected dentin:
Decomposed dentin with destruction of dentinal tubules
and collagen. High concentration of bacteria. Removed
to prevent spread of infection.
Narendranath operative dentistry and endodonticsOperative dentistry-ramya raghu

• Infected dentine is the outer layer and is softened and
contaminated with bacteria. It is irreversibly denatured
and not remineralized
• Affected dentine has a demineralized phase, but not yet
invaded by bacteria. It can be remineralized.
• In clinical restorative treatment of dentine during cavity
preparation it is infected dentine which is completely
removed. The affected dentine, which may be
remineralized after the completion of restorative
treatment, is not removed and is preserved.
5
Affected & infected dentin
Narendranath operative dentistry and endodontics

 Caries-affected dentin interfaces showed a
much thicker hybrid layer than was seen with
non-carious dentin.
 Presumably, the thicker hybrid layer in caries-
affected dentin may be due to the fact that
caries-affected dentin is partially demineralized
and more porous than non-carious dentin.
 Allow deeper penetration of the acid etchant,
leading to a deeper demineralization with
diffused monomer.
5
5Narendranath operative dentistry and endodontics

• The cells exposed dentin should not be insulted by
bacterial toxins, strong drugs, undue operative
trauma unnecessary thermal changes or irritating
restorative materials
• Rapid penetration and spread of caries in the dentin
is the result of the tubule system in the dentin.
• The enamel may be undermined at the DEJ, even
when caries in the enamel is confined to a small
surface area.
• This is due to in part to the spaces created at the
DEJ by enamel tufts, spindles and open and
branched dentinal tubules.
• The dentinal tubules provide a passage for invading
bacteria and their products through either thin or
thick dentinal layer.

Dentinal Hypersensitivity
• Def: Short, sharp pain arising from exposed dentin in
response to stimuli typically thermal, evaporative,
tactile, osmotic or chemical and which cannot be
ascribed to any other form of dental defect or
pathology.
Etiology:
Enamel loss:
• Occlusal wear
• Tooth brush
• Dietary erosion
• Abfraction
• Parafunctional habits

Cemental loss:
• Gingival recession
• Periodontal disease
• Root planning
• Periodontal surgery

Mechanism of pain transmission-
theories of dentin hypersenstivity:
• The exact mechanism is not very clear but several
theories have been proposed to explain this
phenomenon.

Nerve fibers are present within the dentinal tubules
initiate impulses when they are injured and this causes
dentinal hypersenstivity.
Nerve fibers are present only in the predentin and inner
dentinal zones but do not extend all through the DEJ.
These nerves are also absent in areas like root dentin
which is also very senstive.
Substances like potassium chloride, acetylcholine and
histamine are applied to exposed dentin they fail to
elicit a painful response
Direct innervation theory:

Odontoblast deformation/Transducer
mechanism:
Odontoblasts or their processes are damaged when
external stimuli are applied to exposed dentin.
Odontoblastic processes extend only partly through
the dentin and not to upto DEJ.
And also odontoblast membrane potential is too low
to permit transduction.
There were no demonstrable neurotransmitters like
acetylcholine in the neural transmission of the pulp

Hydrodynamic theory
Dentinal tubules are filled with dentinal fluid which is the
intercellular fluid of the pulpal connective tissue.
In the vital tooth there is constant slow flow of the fluid outward
through the dentinal tubules
Whenever exposed dentin is stimulated by tactlie, chemical,
thermal or osmotic stimuli there is rapid movement of the
dentinal fluid toward the pulp or outward. This can cause:
Direct stimulation of the low threshold A-delta nerve fibers in the
pulp.
Indirect stimulation of A-delta nerve fibers in the pulp by
displacing the odontoblastic cell bodies.
Such rapid displacement of dentinal fluid in thousands of dentinal
tubules at the same time produces a cumulative effect and this
causes hypersenstivity.

Clinical features:
• Short, sharp pain response to heat, cold, tactile
stimmuli, sweet or sour foods.
• Considered to be exagerated response of normal-pulp
dentin complex and is not felt on application of
external stimulus.
Management:
 Desensitization by occluding the dentinal tubules.
 Desensitization by blocking pulpal sensory nerves.

• Use of topical agents to occlude
dentinal tubules.
a. Calcium hydroxide
b. Calcium phospahte pastes
c. Silver nitrate
d. Strontium chloride
e. Fluorides
f. Fluoride iontophorosis
g. Potassium oxalate
h. Varnishes
i. Dentin adhesives
j. Placement of restorations
k. Use of lasers
Desensitization by occluding the dentinal tubules:
•Formation of smear layer over exposed dentin.

Desensitization by
blocking pulpal sensory
nerves.
a. Potassium nitrate toothpastes:
Recommended treatment options
for managing dental
hyopersenstivity should be
based on extent and severity of
problem.
At first conservative options should
employed.
If considerable dentin exposure is
present restorations must be
placed.
In generalized hypersenstivity
desensitizing tooth pastes must
be employed.
In case of severe hypersenstivity
endodontic therapy may be
necessary as the final option.

Bonding to dentin
Bonding to dentin is difficult due to:
• Dentin is dynamic tissue that shows changes due to
aging, caries or restorative procedures.
• Considerable amount of organic material and water.
• Dentinal tubules are filled with dentinal fluid .
• Cut dentinal surface is covered by smear layer
• Dentin is in close proximity to the pulp so different
chemical used for eching and dentin bonding may
irritate pulp.
Therefore, dentin is inherently a hydrophilic tissue
and bonding of hydrophobic resins is a challenge.

Developmental in dentin
adhesives:
• Earlier attempts at bonding were
directed towards producing
chemical bond between resin
system either to organic or
inorganic component if dentin.
• An important break through in
dentin bonding was the
development of “total etch concept”
• Demonstrated that etching both
enamel and dentin with 37%
phosphoric acid did not cause any
pulpal damage and Improved the
retention of composite resins in
dentin.

• Another significant development was the
hydrophilic resins.
• Application of these resulted in resin infilteration
of the exposed collagen mesh to form a “hybrid
layer” of resin-infiltered dentin.
• This was responsible for micromechanical bonding
to dentin.

Dentin agents
bonding to inorganic
components:
• Phosphate group
• Amino group
Dentin bonding agents
bonding to organic
component of
dentin.
• Isocynate group
• Carboxylic acid group

Dentinogenesis imperfecta:
• Hereditary developmental disturbances of dentin in
absence of any systemic disorder.
Formely were divided into
• Dentinogenesis imperfecta (Shields I)
• Hereditary opalescent dentin(Shields type II)
• Brandywine isolate(Shields type III).
Oral & maxillofacialpathology-Neville

Clinical features:
•All teeth in both the dentition are affected.
•Deciduous teeth are affected most severely, followed
by permanent incisors, 1st molars, 2nd and 3rd molars
being least.
•Blue to brown discoloration often with a distinctive
translucence
•Radiographically teeth have bulbous crowns, cervical
constriction, thin roots, and early obliteration of root
canals and pulp chambers.
•Shell teeth –normal enamel, extreme thin dentin and
enlarged pulps.

Management:
• The root canals become thread like
and may develop microexposures,
resulting in periapical inflammatory
lesions.
• Risk of enamel loss and severe
attrition .
• Not good candidates for full crowns
because of cervical fracture.
• The newer composites combined
with a dentin bonding agent have
been used in areas subjects to
occlusal wear.

Dentin dysplasia:
• Two major patterns type I and type II.
• Type II is closely related to dentinogenesis
imperfecta.

Clinical features:
Dentin dysplasia type I:
• Referred to as rootless dentin
• Coronal dentin and enamel is
normal and well formed but
radicular dentin loses all
organization
• Wide variation of root organization
is produced because of dentinal
disorganization.
• Shortened roots, extreme mobility
and premature exfoliation.
• Radiographically deciduous tooth
are often severely effected with
little or no detectable dentin.

Dentin dysplasia type II:
• Coronal dentin dysplasia root
length is normal in both
dentition.
• Blue-to-amber-to-brown
• Radiographically bulbous
crowns, cervical constriction,
thin roots, early obliteration of
pulp
• Pulp chambers exhibit
significant enlargement and
apical extensions.
• Altered pulpal anatomy
thistle tube shaped or flame
shaped

Management
• Preventive care is fore most important.
• If periapically inflammatory lesions develop, the root
length guides the therapeutic choices.
• Conventional endodontic therapy requires
mechanical creations of pulp paths.
• Pulp canals are not obliterated endodontic therapy
can readily be done.

Dens Evaginatus
• Cusp like elevation of enamel
located in central groove or lingual
ridge of the buccal cusp of
premolar or molar.
• Normally consists of enamel and
dentin with pulp present in half of
cases.
• Radiographically the occlusal
surface exhibits a tuberculate
appearance and often pulpal
extensions is seen in the cusp.
• Often seen in association of Shovel
shaped incisors
• Typically results in occlusal
problem and often leads to pulpal
death.
• In affected tooth removal of cusp is
often indicated

Refernces
• ORBANS HISTOLOGY AND
EMBRYOLOGY-12TH EDITION.
• RAMYA RAGHU CLINICAL
OPERATIVE DENTISTRY-2nd
EDITION.
• ORAL AND MAXILLOFACIAL
PATHOLOGY-NEVILLE. 3rd
edition
• NARENDRANATH REDDY
OPERATIVE DENTISTRY AND
ENDODONTICS-2nd EDITION

Dentin development

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Viewers also liked

Viewers also liked (8)

Similar to Dentin development

Similar to Dentin development (20)

Recently uploaded

Recently uploaded (20)

Dentin development