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KCS > Pathology of caries > Flashcards

Pathology of caries Flashcards

1
Q

What kind of disease is caries?

A

Bacterial

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2
Q

What type of tissues does caries effect?

A

Calcified tissues of the tooth

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3
Q

How does caries effect inorganic matrix and organic substance differently?

A

Inorganic matrix becomes demineralised

Organic substance is destroyed

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4
Q

What 4 factors are needed to cause a carious lesion?

A

Bacterial plaque
Time
Tooth tissue
Fermentable carbohydrates

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5
Q

What is the critical pH of the tooth?

What process occurs when pH is below critical pH?

A

5.5

Demineralisation

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6
Q

Describe a stephens curve

a) axis
b) shape and reasons for change

A

a) x axis = minutes, y axis = pH
b) pH starts at around 6.8, there is an initial drop in pH as food is eaten (below critical pH). pH then increases to neutral zone via saliva, slower than the initial decrease

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7
Q

What is the substrate for bacteria in the mouth, what does it form?

A

Sugar, forming lactic acid

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8
Q

How does lactic acid effect the tooth surface?

A

Causes demineralisation –> Ca2+ moves from tooth into the surrounding plaque

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9
Q

How does frequency of sugar intake effect demineralisation?

A

Providing sufficient time between intakes Ca2+ will move back into the tooth from plaque = remineralisation
More frequent intake will mean the Ca2+ in plaque can move into saliva and be swallowed, causing the tooth to be more porous and cause white spot lesion

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10
Q

How can caries be classified by site?

A 
Occlusal fissures
Cingulum pits
Interproximal areas
Cervical margin
Root surface
Secondary (recurrent)
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11
Q

How can caries be classified by rate of progress?

A

Acute (rampant)
Chronic
Arrested

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12
Q

How can caries be classified by tissue?

A

Enamel
Dentine
Cemental (root)

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13
Q

How do white spot lesions appear on radiographs?

A

Darker areas on the tooth surface

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14
Q

What are the 4 histological zones of a white spot lesion in enamel caries (from inside out)?

A

Translucent zones
Dark zone
Body of lesion
Surface zone

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15
Q

What structure is lost within the translucent zone?

A

Striae of retzius

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16
Q

What are Striae of Retzius?

A

Long term incremental growth lines in enamel

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17
Q

How does the porosity of the translucent zone of white spot lesion compare to normal enamel, why?

A

More porous, due to increased pore volume and larger pores

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18
Q

How does the mineralisation of the translucent zone of white spot lesions compare to normal enamel?

A

Mineral dissolution of Mg and carbonate but increased F- concentration

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19
Q

Why does the translucent zone of white spot lesions appear structureless?

A

It was formed by the demineralisation process

20
Q

How does the pore volume in dark zone of white spot lesion change?
Describe the size of the pores

A

Increase by 2-4%

Mixture of small and large pores

21
Q

What process occurs within the dark zone of a white spot lesion?

A

Re-precipitation of mineral (dynamic process)

22
Q

What does the thickness of the dark zone of a white spot lesion indicate?

A

Wider DZ = slower advancing lesion

23
Q

What structure is enhanced in the body of a white spot lesion?

A

Striae of Retzius

24
Q

How does pore volume change in body of white spot lesion?

Describe the size of the pores

A

Increase by 5-25%

Large pores

25
Q

What process occurs in the body of a white spot lesion?

A

Demineralisation

Mineral is replaced by water and some organic material from saliva or organic material

26
Q

What is the surface zone of white spot lesion?

A

Intact enamel

27
Q

What process occurs int he surface zone of white spot lesions, what does this result in?

A

Remineralisation due to exposure to the oral environment resulting in increased mineralisation

28
Q

Which histological zone of white spot lesion is the largest?

A

Body

29
Q

In fissure caries what is the shape of the lesion?

Why

A

Cone shaped - spreading wider along the EDJ

Lesion broadens as it approaches dentine due to prism direction

30
Q

Why are occlusal fissures and pits prime areas for caries?

A

Areas of stagnation, plaque forms due to protection from functional wear or tooth brushing

31
Q

Clinically, what should you be aware of when looking at a tooth with fissure caries?

A

The cavity on the surface may be a lot larger beneath, due to spread along the EDJ

32
Q

What are the zones of dentine caries?

A 
Destruction
Bacterial invasion
Demineralisation
Sclerosis
Tertiary dentine
33
Q

What is sclerotic dentine?

A

Odontoblasts response to irritation
Increased deposition of peritubular dentine causing complete occlusion of the tubules
Causes calcification of the odontoblast processes

34
Q

What are dead tracts, where are they found?

A

Empty dentinal tubules containing remnants of dead odontoblasts
Run through zones of sclerotic dentine

35
Q

Why do dead tracts not act as channels for bacterial invasion?

A

Sealed at pulpal end by a layer of hyaline calcified material - eburnoid

36
Q

Where is the most porous part of the dentine lesion?

A

Zone of demineralisation

37
Q

What causes the zone of demineralisation in dentine lesion?

A

Loss of mineral from dentine due to diffusion of acid produced by bacteria in the zone of bacterial invasion

38
Q

Describe the zone of destruction in the dentine lesions

A

No tubular sclerosis so tubules are invaded by bacteria. The tubules coalesce and form liquefaction foci. Cracks form transverse clefts

39
Q

What is the liquefaction foci in dentine caries?

A

An area of destruction parallel to the course of the tubule

40
Q

What direction are transverse clefts in the zone of destruction found?

A

At right angles to dentinal tubules

41
Q

What do the transverse clefts in zone of destruction in dentine contain?
What does this result in?

A

Bacteria and necrotic tissue, causing progressive loss of dentine architecture

42
Q

What is tertiary dentine?

A

Pulpal response to irritation

Layer of dentine formed on surface of pulp chamber deep to dentine caries

43
Q

Describe the structure and mineralisation status of tertiary dentine

A

Tubules are irregular and fewer in number than primary

Mineralisation is variable with areas of hypermineralisation

44
Q

What does cemental caries look like clinically?

A

Superficial softening of cementum at gingival margin

45
Q

What is the shape of lesion in cemental caries?

A

Saucer shaped

46
Q

What factor of cemental caries causes cervical enamel to be undermined?

A

Extensive dental involvement

47
Q

What is a major risk factor for cemental caries?

A

Gingival recession –> oral hygiene very important for these patients

KCS (11 decks)

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