histopathology of dental caries

1. Dr. Ahmed El_Nashar
4. Histopathology of dental caries
1. Enamel caries
1. Smooth surface caries
( examined by electron microscope )
- Permeation of acids within enamel causes a series of submicroscopic changes , recorded by electron microscope as follows …..
1. Loss of the interprismatic or inter-rod substances of the enamel.
2. Increased prominence of the rods.
3. Roughening of the ends of the enamel rods.
4. Degradation of the mucopolysaccharides present in the interprismatic organic substance.
5. Appearance of transverse striations of the enamel rods.
6. Accentuation of the incremental striae of Retzius.
( examined by ground section and transmitted light )
- As the caries process advances, a triangle or a cone shaped lesion with the apex toward DEJ and the base toward the surface of the tooth. Several
zones can be distinguished before actual destruction , Working from backward forward zones appears in the following arrangement ……
1. Translucent zone 2. Dark zone 3. Body of the lesion. 4. Surface zone
initial demineralization Demineralization and remineralization. greatest demineralization. greater degree of remineralization
• Volume of Pores is 1 % of volume of
enamel.
• Volume of Pores is 2-4% of volume
of enamel.
• Volume of Pores is 5 – 25 % of
volume of enamel.
• Volume of Pores is 1 % of volume of
enamel.
• The pores are larger than that in
normal enamel.
• Some of the pores are large but others
are smaller than those of the
translucent zone.
• pores are larger than those found in
sound enamel.
• In this zone 1.2% of minerals are lost • In this zone 6% of minerals are lost • In this zone 24% of minerals are lost.
• Ii appears translucent with transmitted
light.
• This zone is sometimes missing or
only present along a part of the lesion.
• it appears dark with transmitted light
(light brown in color).
• dark zone is narrow in acute caries and
wide in slowly advancing caries
• forms the largest area in the carious
lesion
• The lost minerals are replaced by
unbound water and organic material ,
derived from saliva and
microorganisms
• This area is recognizable clinically as
brown spot
• It appears relatively unaffected.
It is about 40 µm thick.
1. pits and fissure caries
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- As the caries process advances, a triangle or a cone shaped lesion with the apex toward the surface of the tooth and the base toward the DEJ .
Several zones can be distinguished before actual destruction , Working from backward forward zones appears in the following arrangement ……

2. Dr. Ahmed El_Nashar
2. Dentin caries
1, Caries in primary dentin
Early dentinal changes Advanced dentinal changes
Fatty degeneration Dentinal sclorosis Zone of decalcification Bacterial invasion Decomposed dentine
Fatty degeneration of Tome's
fibers of the dentinal tubules.
• a calcification of the
dentinal tubules that tends
to seal them off against
further penetration by
microorganisms
• formed as a result of
reaction of vital dentinal
tubules and vital pulp.
• Initial decalcification
involves the walls of the
tubules by diffusion of
acids.
• then, the dentine matrix is
destroyed progressively by
proteolysis.
• No bacteria present in this
zone.
1. Pure forms of MOs
penetrate D.T., There are
2 waves of MOs..
1st
wave p acidogenic MOs.
2nd
wave p Proteolytic MOs.
2. The decalcification of the
walls of the denlinal tubules
leads to their confluence.
• complete destruction.
• The presence of
considerable amount of
globular dentine accounts
for the rapid spread of
caries in so- called
malacotic or soft teeth.
3. ch. ch. by prescence of ….
Beaded dentinal tubules Liquefaction foci Transverse cleft
• thickening and swelling of the
walls of dentinal tubules at
irregular intervals and increase
the diameter of the dentinal
tubules due to packing of the
tubules by MOs
• They are tubules and filled with
necrotic debris, which tend to
increase in size by expansion
• They are transverse clefts are
extend at right angles to dentinal
tubules
• May be due to extension of caries
1.along the lateral branches of
the tubules
2.along the incremental lines of
dentine.
3.along the matrix fibers which
run in this direction.
2. Caries in secondary dentin
• the same as primary dentin but somewhat slower because the dentinal tubules are fewer in number and more irregular in their course.
• Caries may spread laterally at the junction of the primary and secondary dentine and produces a separation of the two layers.
• Causes of lateral spread of caries at D.E.J may be due to one of the flowing causes……
1. The high amount of organic content of dentino-enamel junction.
2. Branching of the dentinal tubules, enamel tufts and enamel spindles,
3. Direction of the enamel rods.