CDT Dental Materials & Laboratory Techniques 2

Question 1

Which type of investment material is used for casting high-fusing alloys such as cobalt-chromium?

Accepted Answer

Phosphate-bonded investment

Answer

Phosphate-bonded investments withstand the high casting temperatures required for cobalt-chromium and other base metal alloys.

Question 2

What is the primary purpose of using a separating medium on a stone cast before applying wax?

Accepted Answer

To prevent wax from bonding to the stone

Answer

Separating mediums such as tinfoil substitute create a barrier so wax can be removed cleanly without sticking to the stone model.

Question 3

The term 'liner' in a porcelain fused-to-metal restoration refers to:

Accepted Answer

A thin opaque ceramic layer applied over the metal coping

Answer

The opaque liner masks the metal color and establishes the chemical bond between the metal coping and overlying dentin/enamel porcelain.

Question 4

Which hardener is commonly added to acrylic resin to improve its cross-link density and reduce porosity?

Accepted Answer

Ethylene glycol dimethacrylate

Answer

Cross-linking agents like ethylene glycol dimethacrylate (EGDMA) form bridges between polymer chains, increasing strength and reducing residual monomer.

Question 5

When trimming a diagnostic cast, the posterior heel of a maxillary cast should be:

Accepted Answer

Parallel to the mid-palatal raphe

Answer

Trimming the posterior wall parallel to the mid-palatal raphe ensures symmetrical articulator mounting and accurate representation of midline.

(CDT) Certified Dental Technicians Practice Test

(CDT) Certified Dental Technicians Practice Test

CDT Dental Materials & Laboratory Techniques 2