Caries of Enamel (Amaechi 6) Flashcards
(51 cards)
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
