Management of caries

Question 1

What is the multifactorial aetiology of caries?

Answer 1

Caries is caused by a variety of factors e.g.
Plaque accumulation and retention
Frequency of carbohydrate intake
Exposure to acids and frequency
Pellicle
Saliva free of acidogenic bacteria
Fluoride
Protective dietary factors e.g. dairy

Question 2

What are the 3 stages of caries management?

Answer 2

Preventive
Minimal invasive
Restorative intervention

Question 3

Give 5 ways to help patient prevent caries

Answer 3

Assessment of diet (3 day diet sheet)
Causes of extrinsic and intrinsic acid
Effective tooth-brushing
Salivary flow assessment
Optimal fluoride exposures (gels, varnish, mouthwash, toothpaste)

Question 4

Why restore? (4)

Answer 4

'Best denture is no denture'
Failed alternative preventative measures
Function impaired
Loss of contact point and subsequent tooth movement
Aesthetic reasons

Question 5

Why are fissure sealants important?

Answer 5

Fissures in teeth can favour plaque stagnation, especially during eruption of tooth

Question 6

What is a fissure sealant?

Answer 6

Resin coat physically attached to tooth via acid etch technique

Question 7

2 advantages of fissure sealants

Answer 7

safe and effective

does not involve cutting tooth

Question 8

What is preventive resin restoration (PRR?)

Answer 8

PRR placed after minimally excavating existing occlusal caris up to ADJ using tungsten carbide in air-turbine or air-abrasion technique.
Debates as to whether we should do this or not

Question 9

In PRR, what material would be used to restore tooth?

Answer 9

Composite or GIC, then fissure seal unrestored fissures on remaining sound portion of tooth

Question 10

6 instruments for surgical intervention in caries management

Answer 10

Rotary instruments
Hand instruments
Sonic and ultrasonic instruments
Air abrasion
Pulsed Erbium Laser
Chemo-mechanical caries removal (Cariosolv) - not popular anymore but great for kids/ out in field. denatures proteins, then scoop out

Question 11

4 types of rotary instruments

Answer 11

High speed air turbine (400-600,000rpm - a lot of pressure). Diamond bur
Low speed contra-angle (various torques)
Intermediate high speed
Ultra-high speed

Question 12

How do rotary instruments function?

Answer 12

Remove tooth structure by chipping it away or grinding

Question 13

Which bur is a ‘beginner’ bur?

Answer 13

Tungsten carbide

Question 14

What are burs often coated with?

Answer 14

Diamond coated

Question 15

4 shapes of burs and their uses

Answer 15

Flat fissure: suitable for extending cavity along fissure or widen proximal box
Tapered fissure: designed to develop retentive grooves and pinholes
Round: suitable to remove caries and develop retentive holes
Pear shaped: suitable to create undercut

Question 16

What is particularly important when using rotary instruments?

Answer 16

Coolant as they generate heat - could kill tooth

Question 17

4 limitations of rotary instruments

Answer 17

Visual contact with bur head (small)
Application load - tactile sense (esp. high speed)
Lubrication
Annoyance factor (spray, sound and pain)

Question 18

What is a gingival margin trimmer used for?

Answer 18

To plane enamel margins where access is limited and for conservation
Gives nice finish to make filling last longer

Question 19

What is a spoon excavator used for?

Answer 19

For removing caries and for final removal of softened demineralised infected dentine

Question 20

4 advantages of sonic or ultrasonic tips

Answer 20

Good control of caries removal (selective)
Suitable for minimal invasive procedures
Reduced annoyance factor compared with conventional spherical bur (less pain, no drilling noise)
Good view

Question 21

What is air abrasion also known as?

Answer 21

Kinetic Cavity Preparation

Question 22

How does air abrasion work?

Answer 22

Uses kinetic energy of microfine (20-50) particles of alumina in high pressure steam
Removes tooth structure by brittle microfracture
Sickle or contra-angle handpiece used

Question 23

What alternative powders can be used in air abrasion except for alumina?

Answer 23

Sodium bicarbonate, urea, dolomite

Question 24

What are the main indications for air abrasion? (4)

Answer 24

Minimal occlusal cavities localised in enamel
Limited debridement of dentine lesions with no LA
Micro-etching of metallic and ceramic surfaces (crowns) prior to cementation
Removal of extrinsic stains from teeth

Question 25

6 limitations of air abrasion

Answer 25

Distinct learning curve required
Loss of tactile feedback so tendency to overcut
Doesn’t effectively remove smear layer from dentine
Not suitable for grossly carious dentine
Not suitable for pxs/ dentists with asthma or airway disease
Expensive

Question 26

Which laser systems are the most effective for cutting cavities?

Answer 26

Erbium based laser systems

Question 27

How do pulsed erbium lasers work?

Answer 27

Rely on high absorption bands within tooth structure in middle and far infrared regions (OH, H2O, H2CO3, PO3- are major absorbing components of enamel)
Laser transfers water to steam via rapid heating leading to mini explosions and ejection of crystallites
Carious enamel and dentine are rich in water

Question 28

Why don’t teeth get too hot under pulsed erbium lasers?

Answer 28

Evaporated water creates cooling effect

Question 29

4 advantages of laser

Answer 29

Reduced need for anaesthesia
Low annoyance factor
Creates surface suitable for adhesive bonding of restorations (macro-roughing effect)
Suitable for minimal invasive procedures

Question 30

4 disadvantages of laser

Answer 30

No tactile - dentist relies on sound of tooth when ‘hit’ by laser to determine presence or absence of caries
Learning curve
Slower removal of tooth structure
Expensive