CAP2 + 3- Enamel and dentine caries

Question 1

What is dental caries?

Answer 1

progressive destruction of the tooth surface

Question 2

what is dental caries initiated by?

Answer 2

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

Question 3

Depending on the environment , how can caries progress?

Answer 3

• Can progress unhindered to pulp

- Can remineralise (can arrest)

Question 4

What 4 factors are needed for dental caries to occur?

Answer 4

• plaque bacteria
• time
• substrate
• susceptible tooth

Question 5

what can be used to stop a susceptible tooth?

Answer 5

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

Question 6

What does brushing teeth do to prevent caries?

Answer 6

Takes out time factor and can be managed by diet

Question 7

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

Answer 7

• Erosion
• Abrasion
• Attrition
• Abfraction

Question 8

What is erosion?

Answer 8

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)

Question 9

What is abrasion?

Answer 9

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

Question 10

What is attrition?

Answer 10

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

Question 11

What is abfraction?

Answer 11

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

Question 12

What are the key observations of acidogenic theory?

Answer 12

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

Question 13

How is acid produced at tooth surface?

Answer 13

Bacterial fermentation of dietary CHOs

Question 14

what does boiling microbes do?

Answer 14

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

Question 15

What is the enamel structure of the prism core?

Answer 15

– Tightly packed hydroxyapatite

– Little inter-crystalline spaces

Question 16

What is the enamel structure of the prism sheath?

Answer 16

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

Question 17

What is the clinal appearance of enamel caries?

Answer 17

• “white spot lesion”

- Matt appearance

Question 18

what is required to see enamel caries clinically?

Answer 18

– Clean teeth – plaque free

– Dry teeth

Question 19

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

Answer 19

looks darker

Question 20

what does the appearance of enamel caries depend on?

Answer 20

• 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

Question 21

what does enamel and caries look like on a radiograph?

Answer 21

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

Question 22

what are the lesion zones from the advancing front?

Answer 22

•  Translucent zone
•  Dark Zone
•  Body of Lesion
•  Surface Zone

Question 23

Describe the features of the translucent zone.

Answer 23

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

Question 24

What happens to the translucent zone when penetrated by quinoline?

Answer 24

– Appears structure less/translucent

– Quinoline fills prism periphery

Question 25

Describe the features of the dark zone.

Answer 25

- 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

Question 26

Describe the features of the body of lesion.

Answer 26

- 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

Question 27

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

Answer 27

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

Question 28

Describe the features of the surface zone.

Answer 28

- 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

Question 29

what can plaque do for the surface zone?

Answer 29

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

Question 30

What should you not do to a carious lesion?

Answer 30

probe it

Question 31

Describe the pore structure of carious enamel.

Answer 31

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

Question 32

Describe arrested caries.

Answer 32

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

Question 33

what is the appearance of where demineralisation takes place?

Answer 33

dark zone

Question 34

why is dentine a vital tissue?

Answer 34

it controls cell processes

Question 35

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

Answer 35

Toothbrush does not fit

Question 36

what happens when the caries is advancing front AT dentine?

Answer 36

- sclerotic dentine | - DENTINE RESPONSE- reactionary tertiary dentine

Question 37

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

Answer 37

- Demineralisation | - No bacterial invasion

Question 38

what happens when there is a cavitation in the lesion?

Answer 38

Enamel Cavitation: • Demineralisation • Bacterial invasion

Question 39

what happens when the cavitation spreads towards pulp?

Answer 39

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

Question 40

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

Answer 40

- zone of destruction - zone of bacterial penetration - advancing front in dentine - sclerotic dentine

Question 41

Name the defence response of zones of established dentine caries.

Answer 41

- reactionary tertiary dentine | - translucent /sclerotic zone (blocks tubules)

Question 42

what happen if there is rapid progression of dentine caries?

Answer 42

– No sclerosis – Odontoblasts die – Possibly reparative tertiary dentine

Question 43

Describe the advancing front zone.

Answer 43

– Zone of demineralised dentine | – Acid demineralisation, no bacteria

Question 44

Describe the zone of bacterial penetration.

Answer 44

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

Question 45

Describe the zone of destruction.

Answer 45

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

Question 46

what are the 2 main zones in dentine caries?

Answer 46

- outer, superficial zone | - inner, deeper zone

Question 47

Describe the outer, superficial zone.

Answer 47

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

Question 48

Describe the inner, deeper zone.

Answer 48

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

Question 49

How many lesions are in occlusal caries?

Answer 49

2

Question 50

what do the lesions follow in occlusal caries?

Answer 50

prisms

Question 51

why is the lesion wider in occlusal caries?

Answer 51

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

Question 52

How detectable is occlusal caries?

Answer 52

hard to detect -looks intact but damage is severe

Question 53

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

Answer 53

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