CDT Dental Materials & Laboratory Techniques 3

Question 1

Which property describes a material's ability to return to its original shape after the deforming stress is removed?

Accepted Answer

Elasticity

Answer

Elasticity is the property that allows a material to recover its original dimensions once the applied stress is released below the elastic limit.

Question 2

In lost-wax casting, the spruing technique affects which of the following?

Accepted Answer

Metal flow direction and potential porosity sites

Answer

Sprue placement determines the path of metal entry, and improper design can cause turbulence, back-pressure porosity, or incomplete fill.

Question 3

Polyvinyl siloxane (PVS) impression materials set via which reaction?

Accepted Answer

Addition polymerization with no by-products

Answer

PVS materials cure by addition polymerization between vinyl and hydride groups, producing no volatile by-products and exhibiting excellent dimensional stability.

Question 4

What is the purpose of degassing a noble metal alloy before casting?

Accepted Answer

To remove dissolved gases that cause porosity

Answer

Degassing melts the alloy briefly before casting to allow trapped gases to escape, reducing subsurface gas porosity in the final casting.

Question 5

The Shore A durometer is used to measure hardness of which category of dental materials?

Accepted Answer

Flexible silicone and rubber-based materials

Answer

The Shore A scale measures the hardness of soft, flexible materials like silicones, rubbers, and soft denture liners.

(CDT) Certified Dental Technicians Practice Test

(CDT) Certified Dental Technicians Practice Test

CDT Dental Materials & Laboratory Techniques 3