Caries

Question 1

What are the stages of ICDAS?

Answer 1

International Caries Detection and Assessment System
0 - sound tooth after air drying for 5 seconds
1 - opacity/discolouration visible on dry surface
2 - opacity/discolouration visible on wet surface
3 - localised enamel breakdown in opaque enamel
4 - shadowing from dentine
5 - cavitation exposing dentine
6 - extensive distinct cavity with visible dentine

Question 2

What are methods of caries detection?

Answer 2

Must be a clean, dry tooth
- visual/with a mirror
- transillumination
- orthodontic separators
- radiographs
- laser fluorescence
- electrical conductance

Question 3

What factors should you consider when assessing caries risk?

Answer 3

• previous disease
• dietary habits
• socioeconomic status
• fluoride use
• plaque control
• saliva
• medical history
• parental and sibling caries rate

Question 4

Why should you assess a patients risk of caries?

Answer 4

• appropriate components of preventative programme
• appropriate intensity of prevention
• determine recall intervals
• radiograph use

Question 5

Who is H Trendley Dean?

Answer 5

H Trendley Dean calculated the optimal level of fluoride in drinking water to be 1ppm.
- results in maximum caries protection with minimal dental fluorosis

Question 6

Name some topical methods of fluoride delivery and systemic:

Answer 6

Topical:
- toothpaste, mouth rinse, gels, varnishes
Systemic:
- water fluoridation
- drops or tablets
- salt
- milk

Question 7

What is the acute lethal dose of fluoride?
What dose triggers emergency treatment?
Symptoms?
How can fluoride poisoning be neutralised?

Answer 7

15mg/kg bodyweight
A dose of 5mg/kg should trigger emergency treatment
- salivation, nausea, vomiting, difficulty breathing, cardiac failure
Neutralise by drinking milk (calcium), activated charcoal can absorb and sodium bicarbonate.

Question 8

How does fluoride have a protective effect on the structure of enamel?

Answer 8

During remineralisation, fluoride replaces the hydroxyl groups in hydroxyapatite and replace with fluoride ions in the form of fluorapatite.
The critical pH of hydroxyapatite is 5.5, but fluorapatite is 4.5 therefore more resistant to acid attack than hydroxyapatite protecting from demineralisation in the future.

Question 9

Who discovered tooth mottling and what is this called?

Answer 9

Fredrick McKay discovered brown and yellow staining on teeth and is named Colorado Brown Staining
H.V. Churchill first discovered fluoride in the water.

Question 10

What are the 4 things required for caries to develop?

Answer 10

• susceptible surface (tooth)
• bacteria
• substrate (sugar)
• time

Question 11

What are the 4 zones of enamel caries?

Answer 11

• surface zone: relatively intact, 1-2% porosity, highly mineralised fluoride content
• body of lesion: 25-50% porosity, enamel relatively translucent, corresponds to radiographic appearance
• dark zone: porosity 5-10%, consists of large and small pores, not penetrated by quinoline (appears dark), demineralisation and remineralisation occurring
• translucent zone: 1st carious change, loss of 1-2% mineral, few large pores due to loss of prism periphery, appears structureless/translucent when penetrated with quinoline

Question 12

What are the 3 zones of dentine caries?

Answer 12

From the innermost layer towards ADJ:
- advancing front: acid damage produced by bacteria, decalcifying the dentine (acid demineralisation with no bacterial invasion)
- zone of bacterial penetration: bacteria penetrating dentinal tubules, acid damage with bacterial infection such as lactobacilli
At advancing front and zone of bacterial penetration the organic matrix tubular structure remains intact
- zone of destruction: damage to mineral component and proteolytic enzymatic degradation of organic matrix, this relates to the soft leathery dentine clinically

Question 13

Which bacteria are related to caries?

Answer 13

• streptococcus mutans
• strep salivarius
• strep sobrinus
• strep sanguinis
• lactobacilli
• bifidobacteria
  Root caries: actinomyces naeslundii, actinomyces viscosus

Question 14

What did the experiment involving gnotobiotic rats conclude?
What did Hopewood House experiment discover?

Answer 14

• caries is caused by bacteria
  Hopewood House:
• studied delinquent children with a restricted diet free of fermented carbohydrates and restricted meat products
• poor OH but significantly less caries than the average state school child

Question 15

What was the Vipeholm study?

Answer 15

Aim: determine relationship between carbohydrate intake and caries
7 groups: control group, sucrose group (mealtimes), bread at mealtimes, chocolate group (between meals), caramel group, toffee group (4x between meals), toffee group between meals and sucrose solution
- unethical as not got capacity to consent, purposely introducing disease
Conclusions: sugar causes caries, frequency of sugar affects caries rate more than amount of sugar consumed in one sitting, consistency of foodstuffs affects caries rate