ceramics III- machinable materials- QUESTIONS ONLY

lecture given 5/14/2026

Yttria partially stabilized zirconia is able to resist crack propagation due to transformation toughening. This is due to what type of phase transformation:

A. Monoclinic to tetragonal

B. Tetragonal to monoclinic

C. Tetragonal to cubic

B. Tetragonal to monoclinic

Of the following materials, which has the highest flexural strength?

A. Glass ceramics

B. Porcelain

C. Yttria Partially Stabilized Zirconia

C. Yttria Partially Stabilized Zirconia

Pure zirconia exists in what crystal phase at room temperature:

A. Monoclinic

B. Tetragonal

C. Cubic

A. Monoclinic

Fully stabilized zirconia with about 10 mol% of Yttria (yttrium oxide) exists primarily in what crystal phase at room temperature:

A. Monoclinic

B. Tetragonal

C. Cubic

C. Cubic

Pure zirconia with about 3 mol% of Yttria (yttrium oxide) added exists primarily in what crystal phase at room temperature:

A. Monoclinic

B. Tetragonal

C. Cubic

B. Tetragonal

YTZP (“Zirconia”) blocks may be fabricated in a partially fired form and then milled oversized. In order to get an accurate fit:

A. The blocks must have the correct amount of yttria.

B. The blocks must have a low porosity throughout the block.

C. The blocks must have a uniform and accurately measured density.

C. The blocks must have a uniform and accurately measured density.

There is only 0.8 mm of clearance for the machined ceramic restoration you are fabricating for your patient. Which material would you chose:

A. 3Y Zirconia

B. Pure un-reinforced glass

C. MKII feldspathic ceramic

A. 3Y Zirconia

A ceramic crown restoration that was bonded onto the tooth fractured only 1 week after placement. This is most likely because.

A. The tooth was over-prepared.

B. The tooth was under-prepared.

C. The stress of eating mashed potatoes that day overwhelmed the restoration’s mechanical properties.

B. The tooth was under-prepared.

If the density in a YTZP zirconia block is not uniform what most likely will happen to a machined three unit bridge after firing the zirconia?

A. The margins will be sealed.

B. The bridge is warped.

C. Strength increases.

B. The bridge is warped.

You put acid on a glass ceramic crown to etch it. Then you leave to get the rest of the bonding kit. After about 2 minutes you return. The crown de-bonds 1 week later. What is the most likely cause?

A. It was over-etched it.

B. It was under-etched it.

C. It is the patient’s fault.

A. It was over-etched it.

Glass ceramic crowns should be etched with?

A. Hydrofluoric Acid.

B. Phosphoric Acid.

C. Sulfuric Acid.

A. Hydrofluoric Acid.

Why is the use of Silane important for bonding crowns with a glassy matrix?

A. Makes the crown surface rougher.

B. Links the glass matrix to the polymer in the composite resin cement.

C. Makes the crown surface smooth by filling in defects.

B. Links the glass matrix to the polymer in the composite resin cement.

As the transluceny of zirconia based materials increase?

A. Mechanical Properties Increase.

B. Mechanical Properties Decrease.

C. Mechanical Properties Do Not Change.

B. Mechanical Properties Decrease.

As the transluceny of zirconia based materials increase?

A. Resistance to Surface Damage Increases.

B. Resistance to Surface Damage Decreases.

C. Resistance to Surface Damage Does Not Change.

B. Resistance to Surface Damage Decreases.

High transluceny (5Y) zirconia based materials should be used in high stress areas of the mouth?

A. True.

B. False.

B. False.