partial denture alloys

Question 1

what are the 4 types of PDA available

Answer 1

type IV gold
cobalt chrome
white gold
titanium

Question 2

what are the ideal properties of a PDA base

Answer 2

high YM (rigidity) to maintain shape 
high EL to avoid plastic deformation

Question 3

what are the ideal properties of a PDA clasp

Answer 3

lower YM to allow flexure over tooth bulbosity

high EL to maintain elasticity over a wide range of movements v

Question 4

pros and cons to using gold as a PDA

Answer 4

better suited to clasps than base, can overcome this by thickening base but this is expensive

Question 5

type IV gold typical composition

Answer 5

mixture of metals , usually including gold, silver , copper and some others

Question 6

cobalt chrome typical composition

Answer 6

cobalt = majority ,chrome , nickel

Question 7

cobalt in CoCr

Answer 7

improves mechanical properties

Question 8

chrome in CoCr

Answer 8

improves mechanical properties and corrosion resistance

Question 9

nickel in CoCr

Answer 9

increases ductility but slightly decreases strength

Question 10

what is titaniums main downfall as it has good biocompatibility , corrosion resistance and ductility

Answer 10

it requires specialist equiptment

Question 11

what is lighter CoCr or IV gold

Answer 11

CoCr , weighs almost 50% less

Question 12

what is harder CoCr or IV gold

Answer 12

CoCr