Metallic Materials Flashcards
Why are metal alloys as opposed to pure metals used in dentistry?
- Strength
- Toughness
- Hardness
- Corrosion resistance
- Cost affordability
What is the difference between high noble, noble and base alloys
- High noble >60% noble and >40% gold
- Noble >25% noble
- Base <25% noble
List 6 noble metals
- Gold
- Silver
- Platinum
- Paladaium
- Rhodium
- Iridium
What is the difference between high noble and noble alloys
High noble have more gold
What are the four main metals used in metalic casting alloys
- Gold
- Silver
- Copper
- Platinum/Palladium
What are shape memory alloys and what are their benefits
Metals which demonstrate ability to return to a previously defined shape. eg ni ti files
- elasticity 20x greater than SS
- biocompatible so chemically more stable and less corrosive
- fatigue resistance
- MRI compatible
Is silver a noble metal?
Yes but not in dentistry as causes greening of porcelain
What measure is often used now for strength of alloys
0.2% proof stress
High noble alloys are less corrosion prone
True or false
True
Base metals more likely to corrode
What is the ideal cement thickness
20-25 um
Can you clean a CoCh denture in bleach?
NO! No chloride containing solutions. The passivating chromium layer will be disrupted and corrode.
Haz tabs are no go!
What might you do if you are concerned about an abutment tooth on a denture that you want to clasp?
Do a wrought gold clasp instead of CoCh. Higher proof stress and ower E mod so less stress.
