Restorative Materials In Paediatric Dentistry

Question 1

Name some restoratives for paediatrics (6)

Answer 1

• Amalgam
• Composites
• Glass ionomer cements
• Resin modified GIC
• Compomers
• Preformed stainless steel crowns

Question 2

What are some factors to consider for choice of restorative material for child patient (6)

Answer 2

• Clinical situation
• Tooth structure
• Longevity
• Toxicity
• Child compliance
• Parents consent

Question 3

Give some advantages of dental amalgams (6)

Answer 3

• Good longevity
• Cost effective
• Easy to use
• Excellent mechanical properties
• No shrinkage
• Not moisture sensitive

Question 4

What is the minimum depth required of a cavity for a dental amalgam?

Answer 4

2mm min depth

Question 5

What is the age limitation of amalgams?

Answer 5

Not used for under 15 year olds

Question 6

Give some advantages of composites (3)

Answer 6

• Good creep resistance
• Good compressive strength
• Excellent aesthetics

Question 7

What are some limitations of composites? (5)

Answer 7

• Good adhesive bond has to be established
• Polymerisation shrinkage
• Dentine bonding is weaker that enamel
• High wear in contact areas
• Mismatch in thermal expansion coefficient

Question 8

How is shrinkage reduced in composites?

Answer 8

Incremental filling

Question 9

What ions are released by GIC? (2)

Answer 9

• Ca2+

- Al3+

Question 10

Give some advantages of GIC (6)

Answer 10

• Chemical bond to enamel and dentine
• Carboxyl group binds to calcium in tooth apatite
• Fluoride release / uptake
• No shrinkage
• Ease of placement in bulk
• Aesthetic

Question 11

Give some limitations of GIC (4)

Answer 11

• Low strength
• High wear at early stages
• Need protection from dehydration
• Restoration to be supported by tooth tissue

Question 12

Are resin modified GIC water or acid based?

Answer 12

Water based

Question 13

For resin modified GIC what acid base setting reaction takes place?

Answer 13

Glass + Polyacid

Question 14

For RMGIC besides the acid base setting reaction what other setting reaction takes place?

Answer 14

Light-activated free radical polymerisation of methacrylate groups of the polymer (HEMA)

Question 15

How is RMGIC more advantageous than conventional GIC? (3)

Answer 15

• Command set tougher
• Early strength
• Improved longevity

Question 16

Give some key features of Polyacid-modified composite resin compomers (4)

Answer 16

• Fluoride release delayed
• Longevity
• Greater strength than RMGIC and GIC
• Coloured restorations

Question 17

What are Preformed metal crowns (PMC) or Stainless steel crowns (SSC)?

Answer 17

Extracoronal restoration for primary teeth

Question 18

What is PMC/SCC made of? (4)

Answer 18

Iron and Carbon alloy with the addition of Chromium and Nickel

Question 19

What makes PMC/SCC corrosion resistant?

Answer 19

• Resistant to corrosion due to Chromium

- Cr2O3 forms at the surface

Question 20

What % composition of Cr is needed to make the steel corrosion resistant?

Answer 20

Cr>11%

Question 21

Give some advantages of SSC/PMC (5)

Answer 21

• High tensile strength
• Durable
• Preventative
• Cost effective
• Prefabricated sizes

Question 22

Give some limitations of SSC/PMC (3)

Answer 22

• Bad aesthetics
• Complex procedure
• Ni/Cr could be allergens

Question 23

Give examples of some preventative materials (4)

Answer 23

• Toothpaste
• Mouthwash
• Topical fluoride
• Sealants

Question 24

How is fluoride beneficial for teeth?

Answer 24

• Fluoride substitutes for hydroxyl in apatite
• Makes enamel chemically stronger and more acid resistant
• Reduces plaque activity

Question 25

Comment on the thixotropic property of fluoride gels

Answer 25

• Fluoride gel become viscous when pressure is applied (when mouth guard is squeezed around tooth)
• This allows the gel to flow around tooth surfaces
• Once pressure is removed it sticks to the tooth

Question 26

Give some examples of fluoride gels (3)

Answer 26

• Sodium fluoride (NaF)
• Stannous fluoride (SnF2)
• Acidulated Phosphate Fluoride (APF)

Question 27

What is the pH of APF?

Answer 27

pH 3

Question 28

What happens when fluoride varnish is applied to the teeth?

What is produced?

Answer 28

• Solvent evaporates or sets in moist conditions

- A lot of CaF2 is produced

Question 29

What are pit and fissure sealants?

Answer 29

• Sealants used on primary and secondary teeth
• Reduces carries
• Aids in fluoride release

Question 30

What can pit and fissure sealants be based off? (4)

Answer 30

• Resin based
• GIC based
• RMGIC based
• Compomer based

Question 31

Comment on the properties of pit and fissure sealants (4)

Answer 31

• High coefficient of penetration
• High surface tension
• Low viscosity
• Good wetting

Question 32

What is added to BisGMA-based resin sealants to reduce it viscosity? (2)

Why is this done?

Answer 32

• MMA or TEGDMA

- To make sealant more penetrable

Question 33

How are UDMA based resin sealants cured? (3)

Answer 33

• Light-cured
• Self-cured
• Chemically cured

Question 34

What initiates polymerisation in a Cyanoacrylate-based resin sealant?

Answer 34

Polymerisation is initiated by water

Question 35

Cyanoacrylate-based resin sealant;

2 advantages

2 disadvantages

Answer 35

• Low viscosity
• Good penetration
• Low tensile strength
• Low abrasion resistance