Caries of Enamel (Amaechi 6) Flashcards
Caries evolution
- White spot
- Enamel lesion
- Dentin lesion
- Pulpal lesion
The first clinical sign of incipient caries is _______ due to change in optical properties of enamel with _________.
- White spot
- demineralization or hypomineralization
Enamel surface of early lesion is micro-____ but macroscopically _____.
- porous
- sound
Methods for studying incipient caries
- Clinical methods
- Laboratory methods
Transverse Microradiography (TMR)
is _______ of the
mineral level in
incipient caries.
Densitometric
Tracing
Polarized Light Microscopy (PLM) makes use of
1) ____ and ____ of pores
2) Medium’s molecules ____ and _______.
1) Size and number
2) size and Refractive Index
Polarized Light Microscopy (PLM) Media
Quinoline
Thoulet’s medium
Water
1) Advancing front of the lesion
2) 50% of cases
3) 1% pore volume (normal enamel 0.1%)
4 1.2% loss of mineral by volume
5) Rise in fluoride concentration
6) Fall in carbonate, mg, Ca and PO4
7) No loss of organic material
Translucent Zone
1) Superficial to translucent zone
2) Present in 90-95% of cases
3) 2-4% pore volume
4) 6.3% loss of mineral by volume
5) Has some pores smaller than those of translucent zone suggesting remineralization
Dark Zone
During remineralization the Dark zone increases in size, extending into area previously identified as _______.
Body of lesion
Lesions without dark areas show normal dark zones following exposure to ________.
remineralizing fluids
The appearance of a Dark zone was due to _______ occurring at the advancing front of the lesion.
remineralization
1) Has lost a much larger proportion of its mineral matter
2) Always present
3) 5-25% pore volume
4) 24% loss of mineral by volume
5) Increase in bound water and organic content due to saliva diffusion into the zone
Body of the lesion
1) About 10-100 µm thick
2) Always present
3) 1-5% pore volume
4) 10% loss of mineral by volume
5) Higher in fluoride and protein. Lower in magnesium and carbonate.
Surface Zone
A remineralized Lesion showed a wider ______, and a wider _____ than prior to remineralization, at the expense of reduction
in the size of the Body of the lesion.
- Surface zone
- Dark zone
The _______ and the _____ therefore represent areas of active remineralization,
even during lesion formation.
Dark zone and the Surface zone
Crystal dissolution begins
at the center or core of
the hydroxyapatite crystal. The intercrystalline spaces were increased with caries process, due to ________ as evidenced by irregularity of the margins.
slight etching of the surface of the crystals
The dentin is composed, structurally, of ________ extending from the predentin border to the dentino-enamel junction (DEJ).
dentinal tubules
The dentinal tubules which are filled with dentinal fluid house the _______.
odontoblastic processes
The carious process destroys dentin by:
- acid _______
- acid _______
- ______ enzymatic degradation
- demineralization
- hydrolysis
- proteolytic
-softened discolored dentin which has undergone demineralization and partial decomposition. -some calcium phosphate crystals remain within the matrix.
Zone of necrotic dentin (Destruction)
-collagen fibers and collagen fiber
breakdown.
-large masses of bacteria which correspond to
foci of liquefaction
-gas products may produce ellipsoidal spaces
Zone of necrotic dentin
-bacteria confined within the dentinal tubules.
-dentinal tubules may be distended and in
some places destroyed as the result of acid
demineralization.
-confluence of tubules produce bacteria-filled
pools within the dentin.
Zone of infected tubules (bacterial invasion)
- uninfected tubules are frequently found interspersed among infected tubules.
- single infected tubules may extend deep into intact dentin, emphasizing the irregular pattern of bacterial penetration.
- collagen breakdown.
- depolymerization of the nonfibrous ground substance of dentin.
- large number of hydrolytic enzymes.
Zone of infected tubules
_________ is the irreversible demineralized and denatured layer of dentin, not reparable and with bacterial invasion; it fells very soft, moist and easy to remove with a spoon excavator.
Infected dentin
- evidence of decalcification
- no penetration of bacteria
- dentinal tubules appear fairly normal
- loss of peritubular dentin
- decrease of crystal size - hydroxyapatite
- leaf-shaped crystals - octacalcium phosphate
- large rounded isodiametric crystals - whitlockite
Zone of demineralization
Zone of sclerosis: If dentin is damaged the odontoblastic processes die leaving empty dentinal tubules which form areas of ________.
dead tracts
Zone of sclerosis: Dead tracts become filled with mineral and are called ______.
blind tracts
Zone of sclerosis: The dentin of blind tracts is known as _______.
Below this area is an area of _______.
- sclerotic dentin
- Reparative or secondary dentin layer
Zones of dentinal-pulpal complex
- Central zone
- Cell-rich zone
- Cell-free zone (zone of Weil)
- Odontoblastic zone
Contains:
- Blood vessels and nerves
- Fibroblasts
Central zone
Contains:
- Fibroblasts
- Ground substance
- Collagen fibers
- macrophages
- undifferentiated mesenchymal cells
Cell-rich zone
Contains:
- Fibroblast
- Macrophages
- Undifferentiated mesenchymal cells
- Plexus of capillaries
- Nerve plexus of raschokow
- Ground substance
Cell-free zone (Zone of Weil)
Which structure has the following functions:
- production and maintenance of reticular fibers
- differentiation into odontoblasts
Fibroblast
Which structure has the following functions:
-Nutrition
Plexus of capillaries
Which structure has the following functions:
-Neural sensation of the pulp
Nerve plexus of raschkow
Which structure has the following functions:
-Metabolic changes and limits spread of infection
Ground substance
Contains:
-cell bodies of the odontoblasts from which the odontoblastic processes extend through the dentinal tubules into the dentin
Odontoblastic zone
Odontoblast function:
- formation of the tooth by the deposition of ______.
- reduction of the pulp chamber by the deposition of ______ through the life of the tooth
- deposition of _______ to protect the tooth against noxious stimulus
- primary dentin
- secondary dentin
- reparative or tertiary dentin
The reaction of pulp to an invading caries lesion is determined by the rate of the caries attack:
- Rapid: _____
- Slow: _____
- Arrested: _____
- Acute reaction
- No reaction to chronic reaction
- No reaction
Caries is an intermittent process with periods
of ______ alternating with periods of _____.
- rapid activity
- Quiescence
- bacterial toxins
- bacterial enzymes
- antigens
- chemotaxins
- organic acids
- products of tissue destruction
Irritants from invading caries lesion
Permeability increased by the early death of
the odontoblast and its process from
aggressive caries with consequent formation
of _______.
Dead Tracts
Maintenance of dentin thickness by formation of _______ through secretion by odontoblasts of collagen, amorphous material or large apatite
reparative dentin
The amount of reparative dentin is directly
proportional to the amount of ________, but inversely proportional to the rate of _______.
-primary dentin
destroyed
-the carious attack
- plasma proteins
- immunoglobulins
- complement proteins
products of the inflammatory response
Products of the inflammatory response also diffuse from the pulp back into the carious process in an effort to inhibit the ______ of the carious lesion.
bacterial activity
Penetration in the dentin (including reparative
dentin) of bacteria within ____ of the pulp
produces a negligible inflammatory response
of the pulp.
1.1 mm
Penetration within ____ of the pulp produces a significant increase in the inflammatory response.
0.5 mm
A decrease in the permeability of dentin by:
- Formation of _____ through acceleration of peritubular dentin formation to occlude tubules
- Reduction in ____ permeability
- Shielding of the ____ from irritation
- sclerotic dentin
- dentin
- pulp
Pulp Responses:
1. Caries deeply penetrated the enamel or barely penetrated the dentin
2. Increase in the rate of formation of _______.
3. Reduction in dentin permeability
4. Shielding of the pulp from irritation
5. partially or completely filled dentinal tubules
with mineral deposits such as ____ and _____. (Dentinal sclerosis)
- peritubular dentin
- apatite & whitlockite crystals
