Lecture 3

Question 1

This is the gold standard for clinical longevity for tooth colored crowns

Answer 1

MCC

Question 2

What type of crown has best longevity overall?

Answer 2

Cast metal

Question 3

Difference between ACC and MCC prep?D

Answer 3

ACC is more aggressive due to the need for thicker material

Question 4

Microstructure of dental porcelain

Answer 4

SiO4 tetrahedron

Question 5

3 strength mechanisms of porcelain

Answer 5

1. Crystal Reinforcement
2. Stress- induced transformation
3. Stress corrosion

Question 6

How does crystalline reinforcement work?

Answer 6

• Deflects crack during progression (blunting)

- Slows down the crack growth process by interfering with path

Question 7

More crystalline material= ?

Answer 7

higher strength

Question 8

How does stress-induced transformation work and what material does this?

Answer 8

• Zirconia*
• Stress induces the crystals to transform from one lattice state to a different lattice state which increases the volume which closes the crack

Question 9

3 ways to make ACCs

Answer 9

1. “Metal Ceramic Like”: High strength opaque substructure
2. “Minimal Cutback”: Porcelain only in critical esthetic areas
3. “Monolithic”: Moderate strength translucent ceramics

Question 10

Stress Corrosion

Answer 10

• reduced in a moist environment

- Caused by the reaction of water at the area around the crack tip, resulting in an increase in crack size

Question 11

Another name for stress corrosion?

Answer 11

Static Fatigue

Question 12

How to prevent or delay stress corrosion? (3)

Answer 12

1. Metal substrucure
2. Reduce more tooth structure
3. Use stronger/stiffer ceramics

Question 13

Contact initiated failures

Answer 13

1. Partial cone cracks
2. Cone cracks
3. Median cracks
4. Chipping

Question 14

Interface initiated fracture

Answer 14

Radial cracks