Revision

Question 1

What is the procedure taken before undergoing operative care?

Answer 1

➢ Clinical and radiographic examination, determining the radiographic code
➢ Assessing occlusal relationships
➢ Restorative material factors
➢ Patient factors
➢ Consent
➢ Local Anaesthetic
➢ Shade selection
➢ Rubber dam isolation

Question 2

List the depths involved in a class II amalgam restoration.

• Axial width
• Occluso- gingival depth
• Pulpal depth

Answer 2

• Axial width: 2mm
• Occluso- gingival depth: 3.5 - 4 mm
• Pulpal depth: 2.5 - 3mm

Question 3

How do you achieve resistance form in a class II?

Answer 3

Resistance form refers to the ability of the material to withstand tensile loads due to cavity design.

Resistance form is achieved via:

• Flat pulpal and gingival floors that are perpendicular to the long axis of the tooth
• Slightly rounded line angles
• Adequate occlusal and proximal depths

Question 4

How do you achieve retention form in a class II?

Answer 4

Retention form refers to the ability of the material to stay in place based on the cavity design.

Retention form is achieved via:

• Diverging buccal and lingual walls
• Buccolingual dimensions are greater gingivally than occlusally
• Having an isthmus that isn’t placed at or over the axial wall

Question 5

How long should you wait for amalgam to set?

Answer 5

• 1hr= 40-60% strength- tell patient not to eat on that side for 1hr
• 24hrs= 90% maximum strength

Question 6

How long does it take for each stage of the GIC to set?

Answer 6

Dissolution:
* immediate - minutes

Precipitation:

• minutes - 24 hours
• 4-10 minutes clinically early set

Hydration:
* 24 hours - months

Question 7

What are the ingredients in GC Fuji Coat LC?

Answer 7

• Methyl methacrylate
• Dimethacrylate ester
• Urethane acrylate

Question 8

What are the ingredients in G- Coat plus?

Answer 8

• Homogeneously dispersed nanofiller

Question 9

How does GIC bond to tooth and form the ion- exchange layer?

Answer 9

Chemical bonding process:
• Carboxyl group from polyacid penetrated and bond with Ca2+ in enamel and dentine

Fusion bonding process:
• Strontium and Fluoride from the unset ionomer bond with Calcium and Phosphate in enamel and dentine
• They eventually precipitate to form “Inter-diffusion Zone” which is stronger and more acid resistant

Question 10

Describe general GIC bonding

Answer 10

Stage 1: Dissolution (immediate – minutes)
• Hydrogen ion from the polyacrylic acid attacks the glass surface
• Calcium/ Strontium, aluminium and fluoride are released

Stage 2: Precipitation (minutes – 24 hours)
• Calcium/ Strontium and aluminium ions binds to polyanions
• The calcium chains form first, producing a clinically early set within 4-10 minutes, but they are relatively fragile and highly soluble in water
• The aluminium chains form over the next 24 hours which are strong and insoluble, providing the major physical properties of the GIC

Stage 3: Hydration (24 hours – months)
• Cross-links continue to develop and are progressively hydrated making them more rigid

Question 11

Define the three types of occlusion.

Answer 11

 Centric occlusion: upper and lower jaw are in contact

 Lateral excursion or movement: left and right deviation from centric occlusion

 Static occlusion: the study of contacts between the teeth when the jaw is not moving.

 Traumatic occlusion: occlusion that results in injury to the teeth and associated structures

Question 12

Why is it important to check occlusion after a restoration?

Answer 12

 Patient comfort
 Occlusal stability
 Occlusal contacts of other teeth
 Less likely to encounter problems

Question 13

Explain the polymerisation of composite.

Answer 13

1. Initiation:
   ○ Initiate through light curing, chemical curing or dual cure
2. Propagation:
   ○ The resin monomers bis-GMA have double carbon to carbon bonds
   ○ When the monomers are attacked by the initiators, the carbon-to carbon bond splits
   ○ When the bond splits, the molecule is left with a carbon-carbon single bond and a free radical
3. Termination
   ○ The now single bonded carbons causes the monomers to bond to other monomers
   ○ They continuously bond and add to the polymer chain
   ○ Each linkage leaves a free radical available for further reaction
   ○ However, not all monomers are converted to polymers

Question 14

Describe compomers and giomers

Answer 14

Compomer: dehydrated polyalkenoic acid incorporated with filler particles.

Giomers: Fluorosilicate glass are the particles, being pre-reacted with polyacrylic acid.