Metal Alloys

Question 1

What are considered the Noble mettles used in dentistry

Answer 1

Gold (Au), Platinum (Pt) and Palladium (Pd)

Question 2

This melt has the the highest ductility of the noble

metals.

Answer 2

Gold

Question 3

Ductility is…

Answer 3

Solid material’s ability to deform under tensile stress

Question 4

Malleability is…

Answer 4

Solid material’s ability to deform under compressive stress

Question 5

Platinum properties

Answer 5

Resists tarnish and corrosion. Increases the
hardness and strength of gold and is ductile.
Melting temperature of 1755°C

Question 6

Palladium properties

Answer 6

Cheaper than platinum and is used as a
replacement for platinum. White metal with
melting point of 1555°C

Question 7

BASE METALS are?***

Answer 7

Copper (Cu), Zinc (Zn), Silver (Ag)***, Nickel (Ni), Titanium (Ti)

Question 8

Properties of Copper

Answer 8

Copper is malleable and ductile metal with
characteristic red color. It increases strength
and hardness. Melting temperature is 1083° C

Question 9

Zinc properties

Answer 9

Present in gold alloys in quantities of 0.5% to 2%
to act as a scavenger (deoxidizing agent). It also
improves the castability and fluidity of the alloy.
Melting temperature of 419°C

Question 10

Silver properties

Answer 10

Malleable and ductile metal, improves mechanical
properties of gold alloys.
Melting temperature is 960°C

Question 11

Nickel properties

Answer 11

Hard and ductile metal, improves mechanical properties of base metal alloys.

Melting temperature is 1453°C

Question 12

Grains between crystals are called..

Answer 12

grain boundaries

Question 13

Small size of the grains give better properties to the

alloy. They are called…

Answer 13

grain refiners

Question 14

What are the the must common grain

refiners?

Answer 14

Iridium and ruthenium

Question 15

High-noble Alloys qualifications

Answer 15

At least 60% of gold, palladium or
platinum*
■ At least 40% gold**

Question 16

Noble Alloys qualifications

Answer 16

■ At least 25% of noble metal content

■ They could be:
Gold-based (40%)
Palladium-based (77%) with almost no Au
Silver-based

■ Yield strengths and hardness are equal to or
greater than High-noble alloys

Question 17

Noble Alloys main use…

Answer 17

Main use is for crowns and Fixed Partial Dentures (FPD)

Question 18

Base-metal Alloys use

Answer 18

Main use is for crowns, Fixed Partial
Dentures (FPD), Removable Partial Dentures
(RPD), implants, and wrought forms

Question 19

Biocompatibility is related primarily to their…

Answer 19

Corrosion

Question 20

Wrought Alloys

Answer 20

■ Uses
Orthodontic wires (Ti, Ni-Ti or stainless steel)
Endodontic files (Ni-Ti or stainless steel)
RPD clasps (Pt-Au-Pb)