CDT Dental Materials Science 2

Question 1

Which type of gypsum product has the highest compressive strength and is used for die fabrication?

Accepted Answer

Die stone (Type IV)

Answer

Type IV die stone has the highest compressive strength among gypsum products, making it ideal for accurate die fabrication.

Question 2

What is the primary advantage of using addition-cured silicone (VPS) impression materials over condensation silicones?

Accepted Answer

Dimensional stability with minimal shrinkage

Answer

Addition-cured silicones (VPS) produce no by-products during polymerization, resulting in excellent dimensional stability and minimal shrinkage.

Question 3

The elastic modulus (stiffness) of a restorative material is most relevant when evaluating:

Accepted Answer

Resistance to deformation under occlusal load

Answer

Elastic modulus describes a material's stiffness and its ability to resist deformation under applied occlusal forces.

Question 4

Which base metal alloy component is primarily responsible for the natural oxide layer that improves ceramic bonding in PFM restorations?

Accepted Answer

Beryllium or tin

Answer

Beryllium and tin in base metal alloys form surface oxides during oxidation that chemically bond to porcelain for improved ceramic adhesion.

Question 5

A dental wax pattern that exhibits 'flow' at mouth temperature would most likely cause:

Accepted Answer

Distortion of the final casting

Answer

Excessive wax flow at oral temperature causes pattern distortion before investing, leading to an inaccurate final casting.

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