gold alloy

Question 1

what is considered high noble alloy

Answer 1

40wt% Au

Question 2

what is considered noble alloy

Answer 2

25wt% noble

Question 3

what are heat treatments used for

Answer 3

softening, for adjusting, burnishing and polishing, increase ductility, decrease tensile strength and hardness, elastic modulus unaffected

hardening, indicated for restoration, increases tensile strength and hardness, decrease ductility, elastic modulus unaffected

Question 4

how many type of gold alloy are there?

Answer 4

4 types

Question 5

what is type 4 gold alloy used for, what percentage of gold alloy is there

Answer 5

cast partial and complete denture base, lowest 70%, higher ag and Cu to lower melting range

Question 6

what are the general trend from type1-4 gold alloy

Answer 6

gold content decrease
proportional limit increase
elastic modulus increase
strength and hardness increase
ductility decrease
melting range decrease

Question 7

what causes more thermal contraction during casting shrinkage

Answer 7

a high melting range allow a larger range of values from solidification to room temperature

Question 8

what is the average value of casting shrinkage

Answer 8

1.25 % ard thr

Question 9

what are some alternatives to dental casting gold alloy

Answer 9

1. low gold alloy
   below 60% lower tarnish resistance.
2. silver palladium precious alloy: 60% silver 25% palladium, some have copper, white, tarnish and corrosion resistance satisfactory
3. non precious alloy: nickel and chromium, beryllium( improve castability). High mechanical properties but brittle and low ductility low cost.

Question 10

What are some limitation of non precious alloy

Answer 10

nickel may have allergic reactions

beryllium may be hazardous when inhaled