Histopathology of dental caries
Dr. Maji Jose
Dr. Maji Jose
Pit and fissure caries Smooth surface caries
Dr. Maji Jose
Histopathology of dental caries
• Histopathology of Enamel caries
• Histopathology of dentinal caries
Dr. Maji Jose
Histopathology of Enamel caries
Macroscopic picture
• Pit and fissure caries spread in triangular
pattern following direction of enamel rods
with
– base towards dentin and apex towards the enamel
surface.
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•Carious lesion of pits and fissures develop from
attack on their walls.
•In cross section, the gross appearance of pit and
fissure lesion is inverted V with a narrow entrance
and a progressively wider area of involvement closer
to the DEJ.
Dr. Maji Jose
Early and late pit and fissure caries
Dr. Maji Jose
• Smooth surface caries also spread in
triangular pattern with
– base towards the enamel surface and apex
towards dentin.
• In the region of DEJ caries spread laterally and
extend to dentin in triangular pattern with
– base towards the DEJ and apex towards the pulp
Dr. Maji Jose
Dr. Maji Jose
Darling’s Zones of enamel caries
(Zones from deepest to most superficial)
• Translucent Zone
• Dark zone
• Body of the lesion
• Surface layer
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Smooth Surface Enamel Caries – Early lesion
• The lesion is roughly
triangular with the base
at the tooth surface and
the apex (arrow)
pointing towards the
dentin.
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Translucent Zone
Dark Zone
Body of lesion
Prominent striae
of retzius
Intact
Surface zone
Dr. Maji Jose
Zones of enamel caries
Dr. Maji Jose
Zone 1 - Translucent Zone
• Lies at the most advancing front( deeper part)
• First recognizable change
• Not always present
• Polarized light reveals increased porosity in this zone
than normal enamel, with a pore volume of 1%
compared to 0.1% in sound enamel.
• Appear as a translucent zone/ structureless in
longitudinal ground section of enamel when
quinoline is used as the mounting media
Dr. Maji Jose
This zone appear translucent because……
• the mounting media with same refractive
index as enamel, flow into the pours in the
zone, which are located at the prism
boundaries and other junctional sites, making
the structural lines invisible
Dr. Maji Jose
Translucent Zone also shows…
• Increased fluoride content
• Decreased magnesium carbonate rich
minerals
• Around 1.2% mineral lost
• No protein / organic content loss
Dr. Maji Jose
Dark Zone
• Lies adjacent and superficial to translucent
zone.
• Called as positive zone
1. Always present
2. Positive birefringence in contrast
to negative birefringence of normal
enamel.
Dr. Maji Jose
• Polarized light shows pore volume of 2-4%,
but the pore size is smaller than that of
translucent zone. Smaller pore size is due to
represipitation of minerals lost from
translucent zone
• Appear brown in ground section and vary in
thickness
Dr. Maji Jose
• Due to small size of pores, when quinoline
having a large molecular size is used for
mounting, the medium do not flow into the
pore and the pore remain filled with air
making this zone dark.
• when aqueous medium is used as a mountant this
zone appear light
• Mineral lost is 6%
Dr. Maji Jose
Body of the lesion
• Largest zone located between dark zone and
surface zone
• Under polarizes light this zone shows 5% pore
volume at the periphery and 25% at the
center
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• Appear as a relatively translucent zone
compared to normal enamel in longitudinal
ground section.
• Striae of Retzius appear marked in contrast to
the translucency
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• It is the zone of greatest demineralization with
mineral loss of around 24%.
• Corresponding increase in unbound water and
organic content is seen due to ingress of saliva
and bacteria
Dr. Maji Jose
Surface Zone
• Most superficial zone of around 40micons
thickness
• Mineral loss is about 1-10%
• Pour volume is less than 5%
• Shows negative birefringence above the
positive birefringence of body of lesion, when
section is examined in water with polarized
light
Dr. Maji Jose
• Surface layer remain intact, and breaks down
only after caries reaches dentin.
• Greater resistance of this layer is due to
1. greater degree of mineralization
2. high concentration of fluoride
3.grater amount of insoluble proteins
Dr. Maji Jose
Pit and fissure caries
• Similar to smooth surface caries except for
variation in anatomic structure
• Caries begin in relation to fissures which may
show different pattern such as broad or
narrow funnels, constricted hour glasses,
multiple invaginations with inverted ‘y’ shape
divisions and irregularly shaped.
Dr. Maji Jose
Ultra-structural changes
• Scattered destruction of individual apatite
crystals both in prism and their borders
• Progressive dissolution of crystals- broadening
of inter-crystalline spaces
• Increased porosity of enamel
• Crystals at prism border appear larger-
demineralization
• Diffuse destruction of apatite crystals-
bacterail invasion
Dr. Maji Jose
Caries of Dentin…..
• Differs from enamel caries because….
1.Dentin is a vital structure which is
able to show a reparative response.
2. Dentin has more organic -
component
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Macroscopic structure/ pattern of spread
• In both pit and fissure and smooth surface
caries, in the region of DEJ caries spread
laterally and then extend to dentin in
triangular pattern with base towards the DEJ
and apex towards the pulp.
• Apex is more apical to the base, because the
caries follow the direction of dentinal tubules
Dr. Maji Jose
Shape: Dentine Caries
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Dr. Maji Jose
H/P of Dentinal caries….
• Zone of fatty degeneration of Tomes’ dentinal
fibers
• Zone of dentinal sclerosis
• Zone of demineralization/ decalcification
• Zone of bacterial invasion
• Zone of destruction/decomposed dentin
Dr. Maji Jose
Zones in advanced dental caries
• The 5 “D’s” for Dentinal caries.
• Deepest inner zone to outermost zone:
1)Fatty Degeneration
2)Dentinal sclerosis
3)Demineralization
4)Discoloration and bacterial penetration
5)Disintegration and necrosis.
1&2 – vital response. 3,4,5 – bacterial damage.
Dr. Maji Jose
5 4 3 2
1
1.Zone of fatty degeneration of Tomes fibres.
2.Sclerotic dentine zone.
3.Zone of deeper demineralization.
4.Zone of discolouration and bacterial penetration.
5.Necrotic zone (zone of destruction).
Dr. Maji Jose
Zone of fatty degeneration of Tomes’
dentinal fibers
• Earliest change that can be appreciated at the most
advancing front of dentinal caries.
• Dentinal tubules are normal in structure
• Characterized by deposition of fat globules in
dentinal tubules that can be demonstrated by Sudan
red stain.
• Significance of this change may be …
1. predisposing factor that favor dentinal sclerosis.
2. fat may contribute to impermeability of dentinal tubules
Dr. Maji Jose
Zone of dentinal sclerosis
• Seen at the advancing front and sides of
lesion.
• Sclerosis is the reaction of vital dentinal
tubules and pulp.
• Mineral deposition occurs in dentinal tubules
leading to obliteration, that tend to seal them
off against further penetration by micro-
organism.
Dr. Maji Jose
• Dentinal sclerosis is minimal in rapidly
progressing caries and most prominent in slow
chronic caries.
• Appear as translucent in ground section of
teeth under transmitted light and dark under
reflected light.
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Zone of demineralization
• This is a narrow zone superficial to sclerosed
dentin.
• This change precedes bacterial invasion
• Demineralization occur due to diffusion of
acid released by the micro-organisms ahead of
bacterial invasion.
• Micro-organisms are not found in this zone
• This zone is not infected but affected .
Dr. Maji Jose
Zone of bacterial invasion
• In this zone bacteria invade and multiply in
the dentinal tubules
• First wave of organism are acidogenic mainly
lactobacilli that produce acid which decalcify
dentin.
• Second wave is mixture of acidogenic and
proteolytic organisms which attack the
demineralized matrix.
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• Walls of the tubules are softened and
individual tubules may confluence but general
structure of organic component is retained.
• Softened dentinal tubules are extended due to
packing of tubules by micro-organisms and
debris and take an elliptical shape which is
parallel to the dentinal tubules. This is termed
as liquifaction focci of Miller
• Liquifaction focci may be multiple , giving the
tubule a beaded appearance
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Caries in dentin
Colonies of bacteria (purple streaks)
fill dentinal tubules and begin to
digest the organic matrix producing
small caverns called “beads”.
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Bacterial colonies in tubules.
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Bacterial colonies in tubules.
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Zone of decomposed dentin
Transverse clefts filled
with bacterial colonies in
the zone of disintegration
at the surface of the
carious lesion of dentin.
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Transverse clefts
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Bacterial colonies distorting the tubules
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Zone of destruction/ decomposed
dentin
• In this zone the foci of liquefaction enlarges and
increase in number.
• Decalcification of walls of individual tubules leads to
their coalescence
• Expansion of the tubules by further multiplication
and packing of organisms leads to compression and
distortion of adjacent tubules so that their course is
bent around the liquefaction foci.
Dr. Maji Jose
• Destruction of dentin spread through the
lateral branches of dentinal tubules and along
the incremental lines lead to formation of
cracks or clefts which is perpendicular to the
tubules. These are called transverse clefts.
• At this stage the bacteria extend to
peritubular and inter tubular dentin and
architecture of dentin is destroyed
Dr. Maji Jose
• Tertiary dentin/ reparative dentin formation
can also be appreciated at the pulpal end of
affected tubules
Dr. Maji Jose
Caries in secondary dentin
• Runs a similar course to that in primary
dentine.
• Slower: fewer tubuli.
• Sometimes: lateral spread between
secondary dentine and primary dentine.
Dr. Maji Jose
Thank you
Dr. Maji Jose
