Flashcards in 3 - Cobalt Chrome & Stainless Steel Deck (13):
co/cr alloys: dental uses?
- connectors for partial dentures
- clasps: retention
- palates in complete denture (sometimes)
carbon (small amnt)
co/cr: what happens when there is too much chromium in the composition?
max. amnt of chromium used to improve what?
- alloy becomes too brittle
- max. chromium used to improve corrosion resistance
molybdenum: what does it contribute to? x2
- reduce grain size
- improve hardness
carbon: what does it contribute to? x3
what happens if there is too much carbon?
-too much carbon will make the alloy brittle
properties of co/cr? will it be enough for crowns/bridges?
- high casting temperature, 1500-1550deg
- casting shrinkage ~2%
- not accurate enough for crowns/bridges
advantages of co/cr? x5
- can be made thinner than gold for partial denture
- half density of gold
- low corrosion
high biocompatability, but some alloys contain nickel -> can produce allergic response
problems with co/cr?
- difficult to polish
- cannot be burnished
- clasp can fracture
- resistant to corrosion
dental uses of stainless steel?
- dental instruments
- endodontic files
- hand pieces
- partial denture clasps
- mesh for orthodontics
huge variety of properties can be obtained by?
steel is an alloy of?
cast iron has how much carbon?
stainless steel - minimum of how many % chromium?
what is formed in exposed SS?
- by small changes in composition
- carbon (max 2%) and iron
- greater than 2% carbon
- 11% chromium
- a layer of chromium oxide formed
types of stainless steel and examples of each?
- austenitic: ortho wires, denture clasps
- ferritic: non-cutting instruments
- martenistic: cutting instruments, burs etc