Caries and cavity prep

Question 1

Define caries

Answer 1

A reversible (in earliest stages) progressive disease of the dental hard tissues, instigated by the action of bacteria upon fermentable carbohydrates in the plaque biofilm on the tooth surfaces leading to acid demineralisation and ultimately proteolytic destruction of the organic component of the dental hard tissues

Question 2

Define primary caries

Answer 2

Caries lesions on a previously sound tooth

Question 3

Define recurrent (secondary) caries

Answer 3

caries lesions which have developed adjacent to a restoration

Question 4

Define rampant caries

Answer 4

Historically used to describe multiple caries lesions in the same patient. Often arrises in association with early childhood caries or radiation caries

Question 5

Define early childhood caries

Answer 5

Early onset of caries in young children with fast progression - can result in complete destruction of primary dentition

Question 6

Which bacteria are responsible for caries?

Answer 6

1. Steptococcus mutans
2. Lactobacillus - progression of deep lesions
3. Bifidobacteria - root caries lesions

Question 7

Describe how fermentable carbohydrates affect caries

Answer 7

1. Sucrose and glucose
2. Produce acids (lactic, acetic and propionic acid)
3. Initiates demineralisation

Question 8

Which tooth structures are susceptible to caries progression?

Answer 8

1. Depths of pits and fissures
2. Approximal surfaces
3. Smooth surfaces
4. Ledged/overhanging restorations/defective margins

Question 9

What are the 4 factors needed for caries progression?

Answer 9

1. Bacteria
2. Susceptible tooth surface
3. Fermentable carbohydrates
4. Time

Question 10

At which pH does demineralisation occur? Critical pH?

Answer 10

pH 5.5

Question 11

What is a normal pH?

Answer 11

pH 7.0

Question 12

How long does it take for the critical pH to climb?

Answer 12

Approx 60m

Question 13

How do carious lesions present in enamel?

Answer 13

1. Active white spot lesions
2. Brown spot lesion

Question 14

What is an active white spot lesion?

Answer 14

Smooth, frosty white/ opaque non cavitated lesion

Lesion - chalky over time

Rough and micro-cavitated over time

Question 15

What is a brown spot lesion?

Answer 15

Arrested lesion
Porosities filled with deposited mineral and dietary molecules causing staining
Hard and shiny surface

Question 16

What are the carious lesions within dentine?

Answer 16

1. Infected dentine - outermost, superficial, irreparable necrotic zone of destruction. Dark brown, soft, wet and mushy
2. Affected dentine - inner layer, reparable, hard and paler brown, harder, sticky-scratchy
3. Translucent dentine
4. Hypermineralised dentine

Question 17

What are the Black’s cavity classifications?

Answer 17

Class I: Carious lesions on the Occlusal areas or Buccal areas or Lingual Pits on the tooth surface.

Class II: Carious Lesions on the Posterior occlusal and inter-proximal surfaces of the tooth.

Class III: Carious Lesions on the Anterior inter-proximal surfaces of the tooth.

Class IV: Carious lesions on the anterior inter-proximal surfaces of the tooth including incisal corners

Class V: Carious lesions on gingival third of the crown on buccal or lingual surfaces of the tooth

Question 18

What is caries risk?

Answer 18

Probability of an individual developing new carious lesions

Enables implementation of preventative strategies and effective monitoring to encourage the early detection of carious lesions with more and minimally invasive management.

Recheck at short intervals

Risk factors for caries shown to have strong association with risk factors related to diabetes and cardiovascular disease (angina pectoris and obesity)

Question 19

What are the caries risk factors?

Answer 19

1. Bacteria
2. Time
3. Diet
4. Saliva
5. MH
6. Susceptible tooth surface

Question 20

What classifies a high risk caries patient?

Answer 20

1. Frequent sugar intake
2. Drinking unfluoridated water, no fl toothpaste
3. Infrequent cleaning, poor manual dexterity
4. Low saliva flow rate/buffering capacity
5. High S.mutans, lactobacillus
6. New lesions, premature XLA, anterior caries/restorations, partial dentures, ortho fixed appliances

presence of active lesions and a yearly increment of more than 2 new/progressive/filled lesions in the preceding two-three years

Question 21

How do you manage high risk caries patients?

Answer 21

OHI, diet analysis, Fl toothpaste 2500/5000ppm, F mouthwash > 8y (0.05%daily NaF or 0.2% weekly). F varnish 22600ppm or 2.2% (3-6m) Topical remineralising agent CPP-ACP (recaldent)

Recall 3-6m

Question 22

How to manage low risk caries patients?

Answer 22

No active lesions and no history of recurrent restorations in the past 2-3y.

Lesion - standard and active care. high F app. Recall 6-12m

No lesions - standard care, OHI and dietary advice and fluoridated toothpaste/ 12-18m recall

Question 23

Cavity prep for composite

Answer 23

Macro - enamel bevel margin - remove unsupported prisms, increase surface area for seal/bind.

Rounded internal line angles

Micro - 37.5% phosphoric acid removes smear layer and creates micro mechanical retention for resin. Bond.

Question 24

Cavity prep for GIC

Answer 24

Enamel bevel margin
micro - dentine conditioner - 10% polyacrylic acid - modify/remove smear layer to prep surface for chemical adhesion

Question 25

Cavity prep for amalgam

Answer 25

Macro - undercuts, grooves, slots, flat surfaces. prevent displacement and aid retention

Question 26

How to internal line angles help cavity preps?

Answer 26

Reduces internal stresses and risk of crack propagation within a restoration.