W2 CR & AMAL

Question 1

What basically is a composite resin?

Answer 1

Ceramic filled polymers which is set by resin polymerisation.

Question 2

How does composite bond to the tooth?

Answer 2

Chemically bonds to tooth through an ion exchange mechanism known as free-radical polymerisation

Question 3

Can it release fluoride?

Answer 3

Yes

Question 4

What types of composites are available?

Answer 4

Packable and flowable (filled and unfilled)

Question 5

Describe the organic matrix

Answer 5

(Bis-GMA), UDMA, TEGDMA composite made of matrix —> unfilled resin

Question 6

Describe the phase in Organic Matrix (unfilled resin)

Answer 6

Phase that polymerises forming a solid mass that bonds to tooth.

Question 7

What are two disadvantages of the Organic Phase? (Unfilled)

Answer 7

1. Weakest and least wear resistance phase.

2. Absorbs water stain and discolour.

Question 8

What elements/components are in the Inorganic Filler?

Answer 8

1. Silica Particles
2. Quartz
3. Glass (Ba,Sr,Zr)

Question 9

Is the inorganic Filler, filled resin or unfilled?

Answer 9

Filled resin, permitting it is made up of matrix and filler. –> Filled Resin

Question 10

What does the Coupling Agent do?

Answer 10

Chemically bonds and stress absorber

Question 11

What the setting reaction?

Answer 11

Free radical polymerisation

Question 12

What is the setting period of composite resin?

Answer 12

3-40 sec

Question 13

Does it thermally expand?

Answer 13

Yes

Question 14

Does it wear?

Answer 14

Dependent on contract stress, duration and oral environment

Question 15

How does it bond to the enamel?

Answer 15

ion exchange

Question 16

Describe the composition of composite

Answer 16

Organic matrix (Bis-GMA) + UDMA + TEGMA (unfilled)
Inorganic matrix Glass, Quarts, Silicia (filled)
Coupling agent
Accelerator/initiator

Question 17

What is the impact if water contamination on this material?

Answer 17

Would not bond to tooth, as the material is hydrophobic

Question 18

Would i be able to see this material on a radiograph?

Answer 18

Yes, because it is radio-opaque

Question 19

Indication of composite resin

Answer 19

Pits and fissure seals
Anterior restorations
Luting material
Splinting of teeth

Question 20

Contraindications of composite resin

Answer 20

Root caries
Moisture isolation
Potential allergy

Question 21

What is the difference between packable and flowable?

Answer 21

Flowable has less viscosity than packable allowing it to flow into pits and fissures.

Question 22

How do you bond composite to enamel?

Answer 22

Etching margins with 37% phosphoric acid to create dissolution of outer surface of enamel rods is called micromechanical bonding

Resin then penetrate into the microporosities and develop resin tags.

Technique sensitive affected by moisture contamination

Question 23

How do you bond composite to dentine?

Answer 23

3 step process
Etch (do not etch dentin)
Primer
Adhesive

Question 24

Describe the importance of the Depth of Cure

Answer 24

Important for light activated materials. Inadequate incremental placements and light cure can cause
marginal leakage
recurrent caries
pulpal sensitivity
restoration failure due to polymerisation shrinkage,

Question 25

Describe the importance of the Depth of Cure

Answer 25

Important for light activated materials. Inadequate incremental placements and light cure can cause marginal leakage recurrent caries pulpal sensitivity restoration failure due to polymerisation shrinkage,

Question 26

Do composites absorb water and expand?

Answer 26

Yes, this reduces mechanical properties such as hardness and wear resistance

Question 27

Can composites change colour?

Answer 27

Yes, by extrinsic (mouthwash, tea) or instrinsic (physiochemical)

Question 28

What is the quality of radiopacity?

Answer 28

It improves property and enables clinicians to detect recurrent caries and marginal defects on xrays

Question 29

What are the mechanical properties of composite resin

Answer 29

Wear: depends on the contact stress, duration, chemical environment. Increased filled volume increases hardness, wear resistance and fracture toughness. Polymerisation shrinkage: is reduced by incremental placement, use of GIC as liner or base to act as a shock absorber reducing volume of composite

Question 30

How many types of composite resin are there?

Answer 30

3 Self cure Dual cure Light-cure

Question 31

What are the indications for composite resin?

Answer 31

Direct and indirect restorative material Anterior restorations Pits and fissure sealants Luting agents

Question 32

What are the contraindication for composite resin?

Answer 32

High occlusion load Root caries Where moisture control is difficult Large proximal restorations

Question 33

What are the advantages of composite resin?

Answer 33

Aesthetics Conservation of tooth structure Decreased microleakage Radiopacity

Question 34

What are the disadvantages of composite resin?

Answer 34

Polymerisation shrinkage Time consuming Expensive Technique sensitive

Question 35

What are the indications for amalgam?

Answer 35

High occlusal load bearing teeth Ease of placement Aesthetics not important

Question 36

What are the properties of amalgam

Answer 36

Strength | Dimensional Change

Question 37

What is the basic chemistry of amalgam?

Answer 37

The reaction between silver alloy and mercury is called amalgamation. When high-copper alloy particles contact the mercury, the copper, silver, tin and other elements dissolve into the mercury. New solids products begin to crystallize then hardening. Reaction products are called the matrix.

Question 38

What is the clinical handling of amalgam?

Answer 38

1. Mixing (trituation) 2. Condensation 3. Carving 4. Finishing: polishing carries out of a 24> after placement

Question 39

What are the indications for amalgam?

Answer 39

Large restorations High occlusal load bearing teeth Moisture tolerant

Question 40

What are the contraindications for amalgam?

Answer 40

Use in deciduous teeth Anterior teeth Small class I and II restorations where moisture isolation is possible

Question 41

What is the advantage of amalgam

Answer 41

Ease of use Easily to manipulate Inexpensive Excellent wear resistance

Question 42

What is the disadvantage of amalgam?

Answer 42

Non-aesthetic Tarnish and corrosion Galvanic shock Discolouration of tooth

Question 43

What are the classifications of amalgam?

Answer 43

Particle composition Partical shape: Spherical, lathe-cut, or admixed (sphereical and lath-cut). Irregular: provides more resistance to packing, but strong Spherical is more easily condensed.

Question 44

What is the chemistry of amalgam?

Answer 44

Gamma phase (Y) Gamma 1 Y1 and gamma 2 Y2. Gamma 2 increases corrosion, creep and lowers strength. Modern amalgam → low gamma 2 phase due to higher presence of copper. + Eta phase: tin copper combination Copper acts to convert gamma 2 to gamma 1 and formation of silver-copper alloy. Ag + Cu + Y2 = Y1+ Cu/Sn

Question 45

What is the composition of amalgam?

Answer 45

Silver, Copper, Tin, Zinc

Question 46

Describe the strength of amalgam

Answer 46

Strength - amalgam must withstand oral mechancial forces. ↑ compressive and tensile stress results in occlusion exceeds this will fracture. Tensile strenth is approx 12.5% of compressive strength

Question 47

Describe dimensional change

Answer 47

Expansion may result in post-placement sensitivity or protrusion from the cavity, if it contracts it will leave gaps between the restoration leaving it prone to leakage and recurrent decay.

Question 48

Describe what Creep is?

Answer 48

Break down of the margins of the restoration - resulting i a fracture. Low copper amalgams have more breakdown at margins.

Question 49

Describe tarnish and corrosion?

Answer 49

Tarnish results in discoloured restoration, not aesthetic. | Corrosion is a chemical reaction that can pentrate to the body of amalgam - leading to failure.