Unit 308/315 Dental Caries

Question 1

What causes enamel and dentine to demineralise (dissolve)?

Answer 1

Weak in-organic acids created by oral bacteria as they digest carbohydrates.

Question 2

After a carbohydrate source has been consumed, how long does it take the bacteria to digest the sugar in a dental plaque structure?

Answer 2

1-2 minutes, after which demineralisation occurs as the acid produced dissolves a microscopic layer of enamel.

Question 3

How long does it take saliva to neutralise the acid, restore the mouths pH level and repair microscopic demineralisation? What is this called?

Answer 3

Between 20 mins-2 hours. This is called remineralisation.

Question 4

Why do caries spread more quickly in dentine compared with enamel?

Answer 4

Because dentine has a hollow structure and a lower mineral content compared with enamel.

Question 5

What is the name of the cells which try and protect the underlying pulp tissue from the bacteria by laying down secondary dentine?

Answer 5

Odontoblast cells which lie at the ADJ.

Question 6

What is pulpitis and what symptoms will the patient have?

Answer 6

When pulp tissue becomes irritated and inflamed if caries are allowed to spread deep enough. The patient will begin to feel sensitivity to temperature changes and sweet foods. This is because the nerve fibrils within the hollow structures of dentine will be stimulated as caries progresses.

Question 7

What is reversible pulpitis and how can it be treated?

Answer 7

When pulp tissue is inflamed but can still be removed by the dentist and restored with a filling. The tissue will then settle and the tooth will return to normal function.

Question 8

What is irreversible pulpitis and how can it be treated?

Answer 8

When caries reach the pulp chamber (or its immediate surroundings). The level of inflammation is too great to be resolved by simply removing the decay and the pulp will eventually die due to carious exposure. Patient will be in pain and kept awake at night. Can only be treated with endo or XLA.

Question 9

Explain treatment and advice to help prevent caries.

Answer 9

Control of bacterial plaque

Dietary advice including frequency of sugar etc

Topical fluoride application

Fissure sealants

Question 10

Why are patients who consume processed carbohydrates between meal times are of high risk of developing caries?

Answer 10

Provides a constant acidic environment for demineralisation if enamel to occur, with insufficient time between intakes of sugar for the natural defence mechanism of remineralisation to occur. The saliva does not have enough time to neutralise the acid.

Question 11

Name some examples of foods with ‘hidden sugars’.

Answer 11

Tomato based sauces, ketchup, flavoured crisps, ketchup, breakfast cereals, soups, tinned fruit.

Question 12

What are the two methods of topical fluoride application do the dental team carry out?

Answer 12

Fluoride gel applied in trays over all teeth for several minutes. Often used on patients with special needs and/or those with a high caries risk.

Fluoride varnish (Duraphat products) which is applied to individual teeth showing areas of acid attack or root exposure due to gingival recession.

Question 13

How are cavities prepped by the dentist?

Answer 13

All plaque and soft carious tissue is removed. As much enamel and dentine is conserved as possible (the minimum amount of healthy tooth tissue is removed).

Question 14

What are the aims of cavity preparation and restoration?

Answer 14

Restore normal function
Restore aesthetics
Restore retentive shape
Prevent stagnation areas
Alleviate any pain/discomfort
Permanent and long-lasting solution (dependent on patient's standard of OH and diet)

Question 15

What are the 5 methods of achieving retention for plastic fillings?

Answer 15

Undercutting
Dovetail
Dentine pins
Acid etching
Chemical bonding

Question 16

When are temporary fillings likely to be used?

Answer 16

Emergency measures to seal a cavity

During endo treatment when a tooth will need accessing again

To allow a symptomatic tooth to settle before a permanent filling is placed

Question 17

What are the 4 materials used for temporary restorations?

Answer 17

Zinc oxide and eugenol

Zinc phosphate

Zinc polycarboxylate

Gutta percha

Question 18

When is amalgam likely to be used?

Answer 18

Most widely used permanent restorative material for posterior teeth due to good set strength and excellent longevity.

Question 19

What do amalgam capsules contain?

Answer 19

Powdered alloy (silver, copper, tin, zinc) and liquid mercury.

Question 20

During a deep amalgam restoration, why might a cavity lining need to be used? What is the name of this lining?

Answer 20

To insulate the pulp from thermal shock/injury. Calcium hydroxide or zinc based temporary cements can be used for this.

Question 21

When is glass ionomer likely to be used?

Answer 21

Used in permanent restoration fillings. Adhesive to all the hard tissues of the teeth and is therefore used in situation where there’s little natural retention available.

Question 22

What does cavity conditioner do and what is it made of?

Answer 22

Increases adhesion and improves marginal seal. Contains either polyacrylic acid or tannic acid.

Question 23

During a deep glass ionomer restoration, why might a cavity lining need to be used? What is the name of the lining?

Answer 23

To protect the pulp from the acrylic acid in the GIC. Calcium hydroxide is used.

Question 24

When is composite likely to be used?

Answer 24

Most widely used permanent restorative material for anterior teeth.

Question 25

During a deep composite restoration, why might a cavity lining material be used? What is the name of this material?

Answer 25

To protect pulp from chemical shock. Calcium hydroxide or glass ionomer.

Question 26

What are fissure sealants and when are they likely to be used?

Answer 26

They are a caries prevention measure for vulnerable occlusal fissures and pits (stagnation areas). Commonly done on children.

Question 27

What materials can be used for fissure sealants?

Answer 27

Unfilled composite resins e.g Helioseal or glass ionomer

Question 28

What are unfilled composite resins?

Answer 28

Liquid bases containing just the resin without the filler.

Question 29

What are the 5 methods of moisture control?

Answer 29

High-speed suction (wide bore aspirator)
Low-speed suction (saliva ejectors)
Absorbent materials (cwr, cotton pledgets, dryguard)
Rubber dam
Compressed air drying

Question 30

Explain why it is important to finish and smooth restorations properly.

Answer 30

Correct occlusion in harmony with the rest of patient’s dentition

Maximise aesthetics by achieving a polish/lustre

Minimise risk of surface staining

Smooth surface which patient can test with their tongue, ensuring no overhangs or excess material

Question 31

What are the techniques used to smooth/finish restorations?

Answer 31

Fine abrasive stone
Fine abrasive wheels, discs, brushes and strips
Finishing burs
Polishing pastes

Question 32

What matrix system is used on posterior teeth?

Answer 32

Metal band (Siqveland or Tofflemire). Adapts to tooth to prevent overspill in cavities of two or more surfaces (class II).

Question 33

What matrix system is used on anterior teeth?

Answer 33

Transparent matrix strip. Placed interdentally to separate tooth from its neighbour. Strip is transparent to allow light curing to occur through it (as composite is most commonly used on anterior teeth). Strip can either be held manually or with a holder system.

Question 34

What matrix system is used on class V cavities?

Answer 34

Cervical foil matrix system. Foil coated and preshaped for use when restoring class V cavities. Curing lights will not penetrate through them. Used on posterior teeth to produce a smooth cervical margin surface.