metall alloys pros

Question 1

metal alloys for rem vs fixed pros

Answer 1

REM
- cobalt chrome
- gold
- titanium

FIXED
- nickel cobalt chrome
- gold
- titanium
- silver palladium

Question 2

RP

pros and cons for cobalt chrome alloys

Answer 2

Cobalt-chrome alloys
Pros:
Cheap compared to gold
Abrasion resistant, lightweight
High modulus so can be used in thin sections
High yield stress so less likely to be deformed permanently

Cons:
High casting temp
High shrinkage
Low ductility (so maybe not for clasps)
Nickel sensitivity
Difficult to finish/polish

Question 3

RP

pros and cons for gold alloys

Answer 3

These only cast in type 3 and 4 since these have enough copper to be hardened

Pros -> easy to cast/finish/solder
Cons -> expensive, low yield stress so can be deformed, low modulus so hard to use in thin section

Question 4

RP

pros and cons of titanium alloys

Answer 4

Pros -> biocompatible, very corrosion resistant, light
Cons -> difficult to cast, high casting shrinkage, can react to the investment material

Question 5

FP

pros and cons of non-gold metal alloys for fixed pros

Answer 5

Silver-palladium
Cheaper than golds
High melting point and low density = difficult to cast
Tarnish easily

Nickel-chrome alloys
Similar properties to type III gold alloys
Potential for nickel allergy
High shrinkage when cast

Titanium + its alloys
Biocompatible
High melting point and difficult to cast
High shrinkage when cast
Requires special casting equipment

Question 6

pros and cons of gold alloys for fixed pros

Answer 6

High gold 85%, medium 40-60%, low gold 10-20% gold.

High gold alloys
Type I -> low yield stress 60-140MPa, can be burnished to improve marginal fit
Used for small, well supported inlays where forces are low
Type II -> improved properties compared to type I yield stress 40-250MPa, cannot be used in thin section, can still be burnished
Used for larger inlays
Type III -> high yield stress 180-260MPa, can be hardened, difficult to burnish
Used where there are higher forces (inlays/onlays/crowns/short bridges)
Type IV -> v high yield stress 300-390MPa, can be hardened, cannot be burnished so not used for inlays
Used in high stress areas (dentures, long span bridges)

Question 7

FP

which metal alloys can be used to make metal ceramic alloys

Answer 7

all of these metals can be used to make metal ceramic alloys (porcelain fused to metal) – since they can bond to porcelain, have a higher melting range than the firing temp of porcelain, and have no sag/creep

• Gold, silver palladium, nickel chrome, titanium