Week 7 - Cariology - Prevention: Conrtol of caries lesion development and progression

Question 1

What are the 3 important factors in caries control

Answer 1

• plaque control
• fluoride
• diet

Question 2

What month do deciduous teeth erupt

Answer 2

6 months

Question 3

Children should be helped by adults to brush their until until what age

Answer 3

12 YO

Question 4

What concentration of fluoride toothpaste should individuals aged 18 months - 6 years

Answer 4

500-550 ppm

Question 5

What concentration should individuals >6 years use

Answer 5

1000 - 1500ppm

Question 6

What fluoride concentration toothpaste should high risk caries risk adults and teenagers use

Answer 6

5000ppm

Question 7

What what age should children start using fluoridated toothpaste

Answer 7

18 months

Question 8

What type of toothpaste should be avoided

Answer 8

Sodium laurel sulphate containing pastes because high foaming

Question 9

What is the history of using fluoride to clean teeth

Answer 9

• Dr Frederick McKay noticed that in some areas of Colorado teeth has a mottled and stained appearance. Associated with resistance to decay. He suggested the local water supply may have been responsible for this appearance.

Question 10

How does fluoride protect our teeth from decay

Answer 10

• Forming fluorapatite crystals in tooth structure – less soluble than enamel hydroxyapatite (hydroxyapatite critical pH 5.5, fluoride critical pH 4.5)
• Reducing the solubility to tooth structure to acid, inhibiting demineralization
• Promoting remineralization

Question 11

Where can fluoride be found

Answer 11

1. Water fluoridation
2. Addition to salt, chewing gum
3. Prescribed to children as tablets (not available in Australia because it causes fluorosis)
4. Added to toothpastes
5. Professionally applied as gels, varnishes or rinses

Question 12

What is the concentration of water fluoridation

Answer 12

• Optimal level 1ppm F – reduced to 0.6-0.7ppm in the tropics since they drink more water
• Adding F to water has no effect on its taste or smell
• Present in most Australian cities for the last 25-50 years

Question 13

What are symptoms of excesive fluoride ingestion

Answer 13

nausea, vomiting, abdominal pain, usually within an hour

Question 14

What is the dose and treatment of small fluoride ingestion

Answer 14

• Small quantity of F < 5mg/kg, can be neutralized by drinking large volume of milk

Question 15

What is the dose and treatment of a toxic dose of fluoride ingestion

Answer 15

• Toxic dose = 5 mg/kg requires hospital admission

Question 16

What is the lethal dose and treatment of fluoride ingestion

Answer 16

• Lethal dose = 15mg/kg, requires emergency gastric lavage

100ml of 1000ppm toothpaste lethal for 5yo weighing 20kg

20mL of 5000ppm toothpaste

Question 17

What is dental fluorosis

Answer 17

The hypomineralisation of tooth structure caused by chronic systemic exposure to excessive levels of fluoride during critical periods of amelogenesis (early childhood) (it disturbs the mineralization process)

Causes sub-surface enamel all along the tooth becomes increasingly porous (hypomineralised) extending toward the inner enamel.

Question 18

Why is fluorotic enamel more resistant to caries despite being hypomineralised

Answer 18

• Fluorotic enamel has a higher fluoride content
• The fluoride in fluorotic enamel substitutes the OH in hydroxyapatite to form a more acid resistant mineral: fluorapatite
• Fluorotic enamel is more porous: the porosity may allow post eruptive uptake of fluoride and subsequent remineralization to occur to a greater degree, resulting in a well mineralized surface layer of enamel and greater caries resistance
• Severely fluorotic enamel may be hypoplastic as well as hypominerlised – these teeth tend to be more prone to carries

Question 19

What does fluorosis look like

Answer 19

commonly appears as white lines/areas

Question 20

Is there a link between caries and obesity

Answer 20

• There is no link between caries and obesity – they are both multifactorial – however reducing the amount of frequency of sugar intake helps both weight control and caries

Question 21

What is the suggested sugar intake for an adult a day

Answer 21

25g (6 teaspoons)

Question 22

How does sugar cause caries

Answer 22

1. The bacteria metabolise these sugars and produce acids as by products of their metabolism
2. These acids lower the biofilm pH
3. Demineralisation (dissolution) of the tooth surface occurs wen the biofilm pH drops below 5.5
4. Remineralisation occurs when the pH goes back up again
5. De- and remineralization takes place at the interface between biofilm and tooth surface numerous times each day
6. When the pH drops result in a net loss of mineral over time (demineralization > remineralization) caries lesions arise

Question 23

According Stephan’s curve how fast does biofilm pH drop

Answer 23

5 min

Question 24

According to stephan’s curve how long does it take for normal pH to return

Answer 24

60 min as saliva flow buffers acidity

Question 25

What is the importance of saliva

Answer 25

- Saliva is a natural buffer for the acid produced by cariogenic bacteria - In patients with reduced salivary flow, decreased natural buffering capacity prolongs acidic conditions, increasing risk of caries formation

Question 26

What are the causes of reduced salivary flow (xerostomia)

Answer 26

- Medications (e.g. polypharmacy) - Certain medical conditions (Sjogren’s syndrome) - Radiation therapy - Dehydration (coffee)

Question 27

Diet recommendations for caries controls

Answer 27

- Drink plain water - Reduce frequency and amount of sugars - Avoid eating sweets - Avoid in between meal snacks - Eat an apple, carrot or cheese instead - Check liquid medicines are not syrups that are sugar based