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Caries! > Theory > Flashcards

Theory Flashcards

1
Q

define caries

A

progressive destruction of the tooth structure initiated by microbial action at the tooth surface (crown or exposed root)

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2
Q

give the 4 factors that are required to bring about caries

A
  1. susceptible tooth
  2. plaque bacteria
  3. substrate
  4. time
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3
Q

what is the structure of enamel?

A

Prism core in centre and prism sheath in the peripheries

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4
Q

what can be said about the prism core?

A

tightly packed hydroxyapatite with little inter-crystaline spaces

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5
Q

what can be said about the prism sheath?

A
  • less well packed hydroxyapatite = pores
  • pores contain water and organic material
  • allows easier diffusion of acids
  • WHERE DEMINERALISATION STARTS
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6
Q

what does enamel caries look like?

A

white spot lesion that can be seen on clean dry tooth - matt appearance

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7
Q

how can enamel be viewed under a microscope?

A

by using quinoline

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8
Q

why is quinoline used to aid view of enamel?

A

they have the same refractive index so most accurate view

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9
Q

what are the different zones of enamel caries? 4 zones

A
  1. surface zone
  2. body of the lesion (i
  3. dark zone ( in 90-95% of lesions)
  4. translucent zone (in 50% of cases)
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10
Q

how much mineral loss occurs at the translucent zone?

A

1-2%

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11
Q

how does the translucent zone appear under quinoline?

A
  • some large pores (due to prism sheath loss)
  • appears more translucent
  • quinoline fills peripheries
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12
Q

how does the dark zone appear under quinoline?

A
  • dark brown

- porosities of 5-10%

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13
Q

describe the types of porosities seen in the dark zone

A 
large pores
small pores ( not penetrated by quinoline - appear dark)

demineralisation and remineralisation occurring here

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14
Q

what % porosity is there in the body of the lesion?

A

25-50%

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15
Q

how does the body of the lesion (largest part and centre of lesion) appear under quinoline?

A
  • enamel relatively translucent
  • striae of Rezius more obvious (incremental growth lines)
  • corresponds to the radiographic appearance
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16
Q

facts about the surface zone..

A
  • relatively intact
  • 30 micrometres thick
  • highly mineralised due to high Fluoride content at surface
  • porosity of 1-2%
  • protected
  • forms and reforms during caries process (redeposition of mineral dissolved from deeper layers
17
Q

how can caries become arrested and what does it look like clinically and microscopically?

A

due to

  • dietary changes
  • plaque control + fluoride

clinically - brown exogenous stain

microscopically - a wide, well-developed dark zone

18
Q

what occurs as enamel caries advances at adj?

A
  • sclerotic dentine formation mid way into dentine

- reactionary tertiary dentine formation next to pulp

19
Q

what does an intact surface mean for the caries?

A

no bacterial invasion

20
Q

what occurs when there is an intact surface but the advancing front has gone into dentine?

A
  • caries spreads more rapidly and laterally

- more reactionary & sclerotic dentine laid down

21
Q

after cavitation you get ….?….. and this leads to which 3 zones of established dentine caries?

A

bacterial invasion leads to

  • zone of destruction
  • zone of bacterial penetration
  • advancing front into dentine
22
Q

what is the zone of destruction?

A
  • where you have mixed bacterial population - 2ry infectors
  • proteolytic enzymes
  • destroys organic matrix
23
Q

what occurs as the zone of bacterial penetration?

A
  • bacteria into tubules
  • lateral spread via branched tubules
  • lactobacilli
24
Q

what is happening at the advancing front?

A
  • zone of demineralised dentine

- acid demineralisation (no bacteria)

25
Q

what are the 2 main zones of dentine caries?

A
  1. Infected zone

2. affected zone

26
Q

what is the infected zone of dentine caries?

A
  • highly infected
  • irreversibly demineralised dentine
  • proteolytic degradation of the collagen matrix
27
Q

what is the affected zone?

A
  • dentine has been reversibly attacked
  • collagen matrix not severely damaged
  • minimally infected so potential for repair
28
Q

facts about occlusal caries

A
  • effectively 2 lesions
  • dificult to detect
  • widening lesion
  • same zones

Caries! (9 decks)

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