Partial Dentures Flashcards Preview

2 - Dental Material Science > Partial Dentures > Flashcards

Flashcards in Partial Dentures Deck (15)
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1
Q

What are examples of partial denture alloys?

A

Type IV Gold

Co-Cr

Titanium

2
Q

What YM and EL is wanted for partial denture bases?

A

Base :
high YM - to maintain shape in use
high EL - to avoid plastic deformation

3
Q

What YM and EL is wanted for partial denture clasps?

A

Clasp :
lower YM - to allow flexure over tooth
high EL - maintain elasticity over wide range of movement (ie strain)

4
Q

What type of gold are used for partial denture?

A

Type 4

5
Q

How is the heat treatment of gold alloys done?

A
  1. Quench after casting to create fine grains
  2. Anneal to homogenise
  3. If cold working has been done, stress relief anneal
  4. Heat harden
6
Q

What are the properties of gold alloy more suitable for? Clasp or Base?

A

properties more suitable for clasp

need thickness for base (expense)
Gold IV alloys have a higher elastic limit and reduced rigidity, meaning they can endure more elastic deformation and easily flex over the tooth.

7
Q

What is the effect of nickel in CrCo?

A

replaces some Co
improves ductility
slight reduction in strength

8
Q

What is the hardness of CoCr? And what is it better than?

A

BHN 370
much harder than Gold

9
Q

Compare gold and CoCr

A
  • Co-Cr has greater shrinkage and is less ductile (Elongation %) compared to Au IV.
  • Co-Cr is less dense and has a higher YM (rigidity) and Hardness compared to Au IV.
  • The Compressive strength of Au IV and Co-Cr is similar.
10
Q

What partial denture alloy has the best ductility?

A

titanium
(CrCo low ductility)

11
Q

What PDA has the best UTS?

A

stainless steel

12
Q

What PDA has the best density?

A

gold

13
Q

What PDA has the highest hardness and ridgity (YM)?

A

cobalt chrome

14
Q

What PDA shrinks the most?

A

cobalt chrome

15
Q

What are advantages of using titanium?

A

Good biocompatibility

Good corrosion resistance (passive oxide layer)

Parts joined by laser welding