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Endemic Oral disease > CAP2 + 3- Enamel and dentine caries > Flashcards

CAP2 + 3- Enamel and dentine caries Flashcards

1
Q

What is dental caries?

A

progressive destruction of the tooth surface

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2
Q

what is dental caries initiated by?

A

microbial activity at the tooth surface (crown or exposed root)

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3
Q

Depending on the environment , how can caries progress?

A
  • Can progress unhindered to pulp

- Can remineralise (can arrest)

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4
Q

What 4 factors are needed for dental caries to occur?

A
  • plaque bacteria
  • time
  • substrate
  • susceptible tooth
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5
Q

what can be used to stop a susceptible tooth?

A

Fissure seal to prevent - acid etch and apply resin to smooth out surface and make suspectible area non-susceptible

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6
Q

What does brushing teeth do to prevent caries?

A

Takes out time factor and can be managed by diet

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7
Q

what are the 4 non-carious causes of tooth surface loss?

A
  • Erosion
  • Abrasion
  • Attrition
  • Abfraction
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8
Q

What is erosion?

A

Acid from gastric reflex- balemic patients , reflux disorders , low pH from stomach ,palatal surface -palatal erosion
other acid to cause erosion : diet- acidic food(fruit, drinks)

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9
Q

What is abrasion?

A

Abrasion-tooth brush abrasion, tooth wear caused by something outside the mouth touching the tooth (toothpaste), vigorous brushing with whitening toothpaste

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10
Q

What is attrition?

A

Tooth on tooth wear -this can be incisal ,occlusal and aproximal

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11
Q

What is abfraction?

A

Explains cervical notches, weaking of cervical aspect of the tooth ,when you bite hard on something, tooth flexs, cause micro cracks at cerical margins where enamel is thin

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12
Q

What are the key observations of acidogenic theory?

A

– many organisms can produce acid from fermentation of sugar
– Many oral bacteria produce lactic acid
– Sugar/bread + saliva + bacteria + extracted teeth = demineralisation

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13
Q

How is acid produced at tooth surface?

A

Bacterial fermentation of dietary CHOs

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14
Q

what does boiling microbes do?

A

-stopped acid production
– acid production needed starches and sugars
– no acid production if lean meat or fats were the substrate

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15
Q

What is the enamel structure of the prism core?

A

– Tightly packed hydroxyapatite

– Little inter-crystalline spaces

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16
Q

What is the enamel structure of the prism sheath?

A

– Less well packed crystals
– Space (= pores) contains water and organic material
– Allows easier diffusion of acid
– Where demineralisation starts

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17
Q

What is the clinal appearance of enamel caries?

A
  • “white spot lesion”

- Matt appearance

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18
Q

what is required to see enamel caries clinically?

A

– Clean teeth – plaque free

– Dry teeth

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19
Q

what do areas that are demineralised look like when light is shone through?

A

looks darker

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20
Q

what does the appearance of enamel caries depend on?

A
  • Refractive index (RI) of the mounting medium
  • penetration of the medium
  • RI Air = 1.00
  •  RI Enamel = 1.62
  •  RI Water = 1.33
  •  RI Quinoline = 1.62 – a large molecule 
  • Water or air appear dark
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21
Q

what does enamel and caries look like on a radiograph?

A
  • enamel looks lighter on radiograph , but caries looks darker
  • different zones reflecting -different zones of activity
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22
Q

what are the lesion zones from the advancing front?

A
  •  Translucent zone
  •  Dark Zone
  •  Body of Lesion
  •  Surface Zone
23
Q

Describe the features of the translucent zone.

A
  •  1st carious change
  •  Loss of ~1-2% mineral
  •  5-100μm wide
  •  ~50% of cases
  •  Few large pores due to loss of prism periphery
24
Q

What happens to the translucent zone when penetrated by quinoline?

A

– Appears structure less/translucent

– Quinoline fills prism periphery

25
Q

Describe the features of the dark zone.

A

- Dark brown with quinoline
- Seen in 90-95% of lesions
- Porosity now 5-10%
- Consists of:
>Large pores
> Small pores
• not penetrated by quinoline
•  appears dark
- Demineralisation and remineralisation occurring

26
Q

Describe the features of the body of lesion.

A

- the largest part and centre of the lesion
- 25-50% porosity
- enamel is relatively
translucent
- striae of Retzius more obvious
- corresponds to the radiographic appearance

27
Q

Describe the view of the body of lesion in a radiograph.

A

Resin gets into spaces and so looks light because light shines through it
the radiograph under estimates the extent of caries
for caries- bite wing photo- in this if caries looks close to dentine, probably is affecting dentine already

28
Q

Describe the features of the surface zone.

A

- Relatively intact
- ~30μm thick
- Highly mineralised – high F- content 
- Porosity of ~1-2%
> Protected
> Forms / reforms during carious
process?
• Redeposition of mineral dissolved from deeper layers

29
Q

what can plaque do for the surface zone?

A

plaque limits how ions diffuse in and out, forms barrier to diffusion
presence of plaque- gives this surface zone - provides some protection

30
Q

What should you not do to a carious lesion?

A

probe it

31
Q

Describe the pore structure of carious enamel.

A

Translucent zone- acid demineralisation causes spaces in the translucent zone
Dark zone- porous
body of lesion- full of big spaces because the loss of a lot of enamel
Surface zone- porous

32
Q

Describe arrested caries.

A 
> Remineralised
> Changes in environment: 
– Plaque control + F-
– Altered diet
> Can be brown – exogenous stains
> Histologically: wide, well-developed dark zone
33
Q

what is the appearance of where demineralisation takes place?

A

dark zone

34
Q

why is dentine a vital tissue?

A

it controls cell processes

35
Q

why is it hard to clean plaque away from approximate surface?

A

Toothbrush does not fit

36
Q

what happens when the caries is advancing front AT dentine?

A
  • sclerotic dentine

- DENTINE RESPONSE- reactionary tertiary dentine

37
Q

what happens when the caries is advancing front IN dentine at the intact surface?

A
  • Demineralisation

- No bacterial invasion

38
Q

what happens when there is a cavitation in the lesion?

A

Enamel Cavitation:
• Demineralisation
• Bacterial invasion

39
Q

what happens when the cavitation spreads towards pulp?

A

spreads towards the pulp and laterally dentine lesion is wider than enamel (not at a point) as it spreead along ADJ

40
Q

what are the zones in dentine following cavitation from the enamel inwards?

A
  • zone of destruction
  • zone of bacterial penetration
  • advancing front in dentine
  • sclerotic dentine
41
Q

Name the defence response of zones of established dentine caries.

A
  • reactionary tertiary dentine

- translucent /sclerotic zone (blocks tubules)

42
Q

what happen if there is rapid progression of dentine caries?

A

– No sclerosis
– Odontoblasts die
– Possibly reparative tertiary dentine

43
Q

Describe the advancing front zone.

A

– Zone of demineralised dentine

– Acid demineralisation, no bacteria

44
Q

Describe the zone of bacterial penetration.

A

– Bacteria in tubules
– Lateral spread via branched tubules
– Lactobacilli

45
Q

Describe the zone of destruction.

A

– Mixed bacterial population : 2ry infectors
– Proteolytic enzymes
– Destroys organic matrix

46
Q

what are the 2 main zones in dentine caries?

A
  • outer, superficial zone

- inner, deeper zone

47
Q

Describe the outer, superficial zone.

A

– Highly infected
– Irreversibly demineralised dentine
– Proteolytic degradation of collagen matrix

48
Q

Describe the inner, deeper zone.

A

– Dentine has been reversibly attacked
– Collagen matrix not severely damaged
– Minimally infected
– Potential for repair

49
Q

How many lesions are in occlusal caries?

A

2

50
Q

what do the lesions follow in occlusal caries?

A

prisms

51
Q

why is the lesion wider in occlusal caries?

A

Caries follows prism direction- it doesnt reach dentine at a point, it gets wider and so lesion is wider towards dentine

52
Q

How detectable is occlusal caries?

A

hard to detect -looks intact but damage is severe

53
Q

what can be done to treat occlusal (fissure) caries?

A

Non cleans-able fissure becomes cleans-able after fissure seal

Endemic Oral disease (13 decks)

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