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Operative Dentistry Y2 > Applied Dental Materials > Flashcards

Applied Dental Materials Flashcards

1
Q

What hazards are associated with bisohenol A resin ?

A

Caused some oestrogen like effects in mice
Bisohenol a is ingredient in composites but not nowadays
Can be a breakdown product of bis gma or bis dma
No evidence that bisohenol a is harmful to humans

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2
Q

What hazards are associated with methyl methacrylate ?

A

Monomer in acrylic resin can penetrate gloves in minutes

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3
Q

What types of adverse reactions to gloves can occur ?

A

Contact dermatitis, anaphylaxis, sensitisation, respiratory symptoms

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4
Q

What hazards are associated with light curing units ?

A

High intensity light curing units

Some white light units emit UVA light (not diode lights)

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5
Q

What is gypsum ?

A

Calcium sulphate dihydrate

CaSo4.2H2O

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6
Q

What controls the setting expansion of gypsum ?

A

Potassium sulphate
Sodium chloride
Borax

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7
Q

What controls the setting time of gypsum ?

A 
Potassium sulphate
Sodium chloride
Borax
Potassium citrate 
Gypsum 20%
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8
Q

What effect does additional water have on gypsum ?

A

Extends the setting time but produces a weaker mix

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9
Q

What effect does increased spatulation have on gypsum ?

A

Decreases setting time but increases expansion

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10
Q

What is calcium sulphate hemihydrate type 2 ?

A

Beta
(CaSo4)2.H2O
Plaster of Paris

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11
Q

What are the properties of type 2 calcium sulphate hemi hydrate ?

A 
Water to powder ratio is 40-50/100
initial set time is 5-10 mins
Linear expansion is 0.2-0.3%
Compressive strength is 24mpa 
Tensile strength is 0.6 mpa
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12
Q

What is the setting reaction of calcium sulphate hemihydrate ?

A

(CaSo4)2H2O + 3H2O —–> 2caSo4.2H2O heat
Hemihydrate in suspension
Heavily saturated calcium sulphate
Ions form on nucleus of crystallisation

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13
Q

What is type 3 calcium sulphate hemihydrate ?

A

Dental stone

Alpha

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14
Q

What are the properties of type 3 calcium sulphate hemihydrate ?

A 
Water to powder ratio is 25-35/100
initial set time is 5-20 mins
Linear expansion is 0.1-0.2%
Compressive strength is 70mpa 
Tensile strength is 15mpa
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15
Q

What is type 4 calcium sulphate hemihydrate?

A

Alpha modified, die stone, largest crystal size

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16
Q

What are the properties of die stone?

A 
Water to powder ratio is 25-35
initial set time is 5-20 mins
Linear expansion is 0.1-0.2%
Compressive strength is 75mpa 
Tensile strength is 20mpa
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17
Q

What are the advantages of die stone ?

A

Good colour contrast
Reasonable strength
Economical
Good working time

18
Q

What are the disadvantages of die stone ?

A

Brittleness

Abrasion

19
Q

What are the advantages of electroplating ?

A 
Accurate 
Hard 
Inexpensive 
Good abrasion resistance 
Difficult to damage
20
Q

What are the disadvantages of electroplating ?

A

Time consuming (18hrs)
Cyanide
Bad colour contrast
Poor wax adaptation

21
Q

What is the composition of the copper electrolyte used for electroplating ?

A

Copper sulphate 200g
Absolute alcohol 2ml
Sulphuric acid 30 ml
Distiller water 1000ml

22
Q

What is the composition of the silver electrolyte used for electroplating ?

A

Silver cyanide 36g
Potassium carbonate 45g
Potassium cyanide 60g
Water 1000ml

23
Q

Give an example of a diluent resin

A

TEGDMA

24
Q

What is the filler in a resin based composite ?

A

SiO2

25
Q

What is the function of the filler in a composite ?

A

Control shrinkage and coefficient of thermal expansion
Aesthetics
Mechanical properties

26
Q

What other fillers may be in a composite ?

A

Barium or strontium

Ground up composite

27
Q

What is the purpose of a silane in composites ?

A

Coupling agent

Bond filer particles to resin

28
Q

What is the initiator in composites?

A

Camphorquinone

Starts polymerisation reaction

29
Q

What is the activator for composites ?

A

Blue light 470 nm

30
Q

I hat is the purpose of the activator in composites ?

A

Stimulate initiator to release free radicals

31
Q

What is the inhibitor in composite resins ?

A

Hydroquinone

32
Q

What is the shrinkage of composites ?

A

3 %

33
Q

How does filler loading affect thermal expansion and shrinkage ?

A

Decreases as filler loading increases

34
Q

What are the effects of water sorption on composites ?

A

Warpage, discolouration, reduced mechanical properties

35
Q

Where does water go if it enters a composite restoration ?

A

Into the resin
In voids
In the resin filler interface

36
Q

What affects the depth of cure of composite ?

A

Oxygen inhibition

Shade

37
Q

What are the components of a denting bonding system ?

A

Enchant
Primer
Sealer

38
Q

What Is the purpose of an enchant ?

A

Remove pellicle, open tubules

39
Q

What Is the purpose of the primer ?

A

Forms bond, reactive groups bond to dentine and free mma groups available to bond to resin

40
Q

What is silorane ?

A

Cyclic monomer from oxirane and siloxanes

41
Q

What is the advantage of silorane ?

A

Reduces polymerisation shrinkage of composite to

Operative Dentistry Y2 (7 decks)

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