Adhesion/Luting and Metals

Question 1

Retention is achieved by what?

Answer 1

• Friction
• Adhesive joint
• The cement
• The restoration

Question 2

What 4 things do some bonding agents contain?

Answer 2

1-Nanofiller
2-Fluoride
3-Antimicrobial ingredients
4-Desensitizers

Question 3

How are luting materials classified?

Answer 3

-length of time the are expected to function(Provisional: easier/more temporary
Definitive: Function longest possible time)
-setting mechanism (acid based or polymerization)

Question 4

What is the main challenge in bonding to dentin or enamel?

Answer 4

maintaining moisture without being to wet or too dry

Question 5

What do all amalgams contain?

Answer 5

mercury

Question 6

What are the primary components of amalgam alloys?

Answer 6

• Silver
• Tin
• Copper
• Indium, zinc, platinum, palladium (lesser amounts)

Question 7

What role does zinc play in amalgams?

Answer 7

scavenge metal oxides (can cause delayed expansion if water saliva or blood contact the amalgam)

Question 8

What are the phases of amalgam from strongest to weakest?

Answer 8

y(Ag3Sn) > y1(Ag2Hg3) > y2(Sn7-8Hg) > voids

Question 9

How does Copper make the amalgam stronger?

Answer 9

Forms Cu3Sn and keeps gamma 2 (Sn7Hg) phase from forming

Question 10

What are the 3 kinds of amalgam?

Answer 10

1-Lathe-cut
2-Spherical
3-Admixed

Question 11

What three techniques are used to manufacture indirect restorations?

Answer 11

1-Casting
2-Milling
3-Ceramming

Question 12

What are the 4 most common base metal alloys for RPD and FPD?

Answer 12

1-Nickel-chromium (PD, Porcelain, crowns/bridges)
2-Cobalt-chromium (PD, porcelain)
3-Titanium (PD, crown/bridge, implant)
4-Wrought stainless steel (endo instrument, ortho wire, crowns)

Question 13

What are 5 things to look for in a dental alloy?

Answer 13

1-Non-toxic
2-resistance to corrosion
3-phys and mech properties
4-ease of use
5-expense

Question 14

What does chromium help with?

Answer 14

Resist tarnish

Question 15

What does Molybdenum help with?

Answer 15

increase strength

Question 16

What does aluminum help with?

Answer 16

Forms Ni3Al to increase tensile and yield strength

Question 17

What does beryllium help with?

Answer 17

lowers fusion range, adversely affects ductility and corrosion resistance

Question 18

What does silicon and manganese help with?

Answer 18

fluidity and castability

Question 19

What are the main advantages of using noble metals?

Answer 19

Resist oxidation, tarnish and corrosion during formation process and in the mouth

Question 20

Though palladium is used frequently what is a possible disadvantage?

Answer 20

absorbs H2 gas changing conductibility and making it difficult to cast

Question 21

What are iridium, ruthenium and rhodium used for?

Answer 21

grain refiners because of high melting points (nucleating centers)

Question 22

What does tin do in alloys?

Answer 22

increases hardness and brittleness

Question 23

What does gallium do in alloys?

Answer 23

creates oxides necessary for porcelain bonding to alloys

Question 24

What is the old ADA classification for metals?

Answer 24

• Type I: inlays subject to slight stress
• Type II: most cast inlays
• Type III: crowns, bridge abutments, precision inlays
• Type IV: Cast RPD w/ Clasps, precision bridge

Question 25

What is the new ADA classification for metals?

Answer 25

1-High noble: noble metal >60% wt, or gold content >40%
2-Noble metal if >25%
3-Predominantly base metal if

Question 26

What are the properties of Ni-Cr for crown/bridge?

Answer 26

• high hardness and elastic modulus
• difficult to cast
• high solidification shrinkage
• toxic vapor/dust
• nickel is an allergen

Question 27

What are the properties of Co-Cr for crown/bridge?

Answer 27

• better corrosion resistance
• higher temperature needed for casting
• difficult to clean