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IRS > Casting alloys > Flashcards

Casting alloys Flashcards

1
Q

What are dental casting alloys?

A 
Gold alloys 
Precious metal alloys
Nickel chromium alloys 
Cobalt chromium alloys 
Titanium alloys
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2
Q

What are the casting alloys for RPD;s?

A

CoCr
Ti
Ti alloy
Gold

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3
Q

What are the metal-ceramic casting alloys (bonding alloys)

A

CoCr
Ti
Gold (high, medium, low )
Ti alloy

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4
Q

What are bonding alloys used for?

A

All metal restorations

other metal allots can not be used for bonding to ceramic

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5
Q

What are the desirable properties of casting alloys?

A 
Biocompatibility 
Corrosion and tarnish resistant
Optimum mechanical properties 
Bond to ceramic 
Aesthetic 
Cheap
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6
Q

How do you cast an RPD?

A

Have a mesh for where acrylic will hold on to the denture
Add clasps were want to gain retention join up with wax to get connection between the connector and saddle areas - get a wax pattern for the partial denture which needs to be converted into metal
Create sprues out of the pieces of wax to form a channel from the outside of the mould to the inside - wax melted out, metal flows in
Paint on refractory material to create the mould, fill bulk of mould with more coarse refractory material
Casting machine has crucible in the middle to heat up the metal
CoCr in the crucible, once molten the metal shoots out and jumps into the mould
Allow it to cool down, take hammer and hit to break off the refractory material
Metal casting covered in metal oxide material - get rid of it by putting in a shot blaster which has particles of alumminium oxide which blasts off the stuff on the surface of the metal
Have the finishing process to polish up - by trimming the sprews off, use burs to trim off the excess and tidy edges
Put in electrolytic brightener to polish the fitting surface of the denture
Then polish the polishing surface with burs
Have framework ready to put teeth on

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7
Q

What is the casting temp of CoCr

A

1500 degrees c

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8
Q

What is SLM production a production method for?

A

Removable partial dentures

CoCr or Ti

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9
Q

What is SLM?

A

An easier way to produce
Can design in CAD package and manufacture the framework
Scan model, design denture and send off to place where does laser sintering, still needs to be polished after

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10
Q

What are the different materials used for all metal restorations?

A 
Type I-IV Au - gold alloys which all others are compared to 
Other precious metals 
CoCr
NiCr
Ti
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11
Q

What is the process for casting all gold restorations?

A

Make wax pattern of crown you’re trying to reproduce
put a sprue on
Put on to a ring for, put ring over the top, pour the investment into casting ring to make the mould
Once full, let it set, use different casting machine
Shoot the gold into heated up mould then get gold casting
Use acids to get the oxide off the surface rather than shot-blasting
Trim off the sprew and make adustments to the fitting surface

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12
Q

What is the amount of Au in type I alloy and what is it used for?

A

Soft
80-90
Inlays - can burnish the margins and get a good marginal seal

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13
Q

What is the amount of Au in type II alloy and what is it used for?

A

Medium
75-78
Onlay

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14
Q

What is the amount of Au in type III alloy and what is it used for?

A

Hard
62-78
Crowns

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15
Q

What is the amount of Au in type IV alloy and what is it used for?

A

Extra hard
60-70
Crown, bridge, post and core, RPD

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16
Q

When the amount of Au in the alloy decreases, what increases?

A

Copper

17
Q

Which gold alloy would you use in non load bearing areas?

A

types 1 and 2

for inlays and onlays

18
Q

Which type of Au alloy has the highest yield strength?

A

IV

19
Q

Why is yield strength important?

A

Tells us when it will deform - need to know how long it will last

20
Q

What are the different medium and low-gold alloys?

A 
Stabilor G (medium gold) 
Palaginor 2 (low gold)
Realor
21
Q

What are the different Ag-Pd alloys?

A

Palliag W
Palliag M
Mattico

22
Q

What are the different routes of production for the alloys?

A

Casting
Selective laser production
Milling and un-sintered milling

23
Q

How are bonding alloys different to casting alloys?

A

Melting temperature - higher because going to sinter ceramic on the surface of the metal - metal sintering temp is 950-1000 degrees C
The TEC - needs to match the ceramic that will go on the surface of the metal sub-structure
Oxide layer - enable the bonding of the ceramic to the sub-structure, acts as wetting surface for the ceramic
Modulus of elasticity - needs to be stiff of the ceramic will fracture off

24
Q

What are the different bonding alloys?

A

Au alloys
NiCr
CoCr
Ti alloys - difficult for ceramic to bond to

25
Q

What are the groups of casting alloys?

A

Those used for RPD’s
Those for all metal restorations
Bonding alloys

IRS (16 decks)

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