ICP L11: Gaining access and removal of carious tissue

Question 1

What is dental caries

Answer 1

• reversible but progressive disease affecting dental hard tissue
• initiated by bacteria in a plaque biofilm
• fermenting carbohydrates produces acids which demineralise the inorganic component s
• there is proteolytic destruction of organic components

Question 2

What isolation techniques are used

Answer 2

1. Rubber dam - protects airways, reduces aerosol production
2. Cotton wool rolls - absorbs saliva and fluids, need regular changing
3. Dry guards - sit over parotid duct and have a greater absorption capacity than cotton wool rolls
4. Aspiration - by nurse

Question 3

What conditions need to be attained for caries detection

Answer 3

• good vision and magnification
• good illumination
• clean tooth surface
• examination in wet and dry conditions
• round ball explorer

Question 4

Why is a sharp tool not used to examine whether a patient has caries

Answer 4

Because if there is caries but it is non-cavitated, the sharp instrument could cause cavitation which will need repairing; without cavitation the lesion could be reversed by remineralisation alone

Question 5

Where are the three main sites of caries development

Answer 5

• pits and fissures/cingulum
• approximal below contact area between teeth
• smooth surface

Question 6

What does 0 score on the ICDAS scale indicate

Answer 6

• No/slight change in enamel translucency after prolonged air drying
• No enamel demineralisation or narrow zone opacity

Question 7

What does 1 score on the ICDAS scale indicate

Answer 7

• Opacity/discolouration (greying) of enamel (white spot) hardly visible on wet tooth and so needs drying to see
• Enamel demineralisation of outer 50%

Question 8

What does 2 score on the ICDAS scale indicate

Answer 8

• Opacity/discolouration visible without air drying and no clinical cavitation
• Enamel demineralisation through inner 50% to outer 1/3 of dentine

Question 9

What does 3 score on the ICDAS scale indicate

Answer 9

• Localised breakdown in opaque/discoloured enamel and greyish discolouration/shadowing of underlying dentine
• Demineralisation of middle to inner 1/3 dentine

Question 10

What does 4 score on the ICDAS scale indicate

Answer 10

• Gross cavitation in opaque/discoloured enamel exposing underlying dentine
• Demineralisation of inner 1/3 dentine towards pulp

Question 11

What needs the be considered when taking reading from bitewing radiographs in regards to approximate caries

Answer 11

That the radiograph always under estimates the extent of caries

Question 12

Black classification I caries

Answer 12

Cavity in pits/fissures on occlusal surfaces of posterior teeth or lingual maxillary incisors

Question 13

Black classification II caries

Answer 13

Cavity on proximal surfaces of posterior teeth

Question 14

Black classification III caries

Answer 14

Cavity on proximal surfaces of anterior teeth

Question 15

Black classification IV caries

Answer 15

Cavity on proximal surface of anterior teeth involving incisal edge

Question 16

Black classification V caries

Answer 16

Cavity on cervical 1/3 of tooth (smooth surface caries)

Question 17

Describe development of approximate caries

Answer 17

Starts below contact point, over time the marginal ridge will break down and leave a cavitated interproximal area

Question 18

What are bitewing radiographs useful for

Answer 18

Good inter proximal caries detection

Not good for occlusal

Question 19

What are dental panoramic tomographs useful for

Answer 19

Looking at eruption patterns, wisdom teeth and periodontal health

Question 20

What are periapical radiographs useful for

Answer 20

Assessing apical status

Question 21

How are sensibility tests done

Answer 21

These test the nerve supply to tooth and indirectly assess tooth vitality (as this would be directly tested through measuring blood flow)

1. Thermal testing
2. Electronic pulp tester
3. Test cavity

Question 22

What is the aim of enamel preparation when removing a carious lesion

Answer 22

• gain full access to the lesion
• remove demineralises/weakened and unsupported enamel
• create a sound peripheral margin to seal with the restorative material

Question 23

How is dentine removed in a carious lesion

Answer 23

Need to identify caries infected and affected dentine

• identify peripheral extent of caries to EDJ
• excavate caries from EDJ to clear periphery of lesion
• move towards pulp from the periphery
• sound dentine must be lest at the junction

Question 24

What is the difference in equipment used for enamel and for dentine removal in cavity restoration prep

Answer 24

Enamel prep = high speed air rotor with diamond or tungsten carbide burs

Dentine prep = slow hand piece with steel rose head burs or hand excavators

Question 25

What type of bur should be used when removing dentine

Answer 25

The largest bur that can fit into the cavity so that it will give the smoothest cavity base possible

Question 26

What are the clinical differences between caries infected and affected dentine

Answer 26

Infected = dark brown, soft, sticky

Affected = paler brown/translucent, sticky, flakey, scratchy, leathery

Question 27

What is cavity retention

Answer 27

The property of a cavity to resist displacement of the restoration in the direction the restoration is placed

Question 28

What is cavity resistance

Answer 28

The property of a cavity to resist displacement of the restoration in any other direction (better when wider at base)