CDT Dental Materials & Laboratory Techniques

Question 1

What is the main purpose of dental waxes in the laboratory?

Accepted Answer

To create patterns and models for casting

Answer

Dental waxes are fundamental in the laboratory for creating precise patterns of dental restorations like crowns, bridges, or partial denture frameworks. These wax patterns are then embedded in an investment material, and the wax is subsequently burned out. This 'lost wax technique' leaves a hollow mold, which is then filled with molten metal or ceramic to produce the final, accurately shaped dental appliance.

Question 2

Which material is commonly used for dental impressions?

Accepted Answer

Alginate

Answer

Alginate is a widely utilized impression material in dentistry due to its ease of use, cost-effectiveness, and ability to capture sufficient detail for many applications. It is an irreversible hydrocolloid that sets quickly, making it ideal for creating study models, orthodontic appliances, and preliminary impressions for dentures. While other materials exist, alginate remains a popular choice for general dental impressions.

Question 3

What is the purpose of using a dental articulator?

Accepted Answer

To simulate jaw movements for accurate restoration alignment

Answer

A dental articulator is a mechanical device designed to simulate the movements of a patient's jaw. By mounting dental models on an articulator, technicians can accurately assess and adjust the occlusion (bite) of restorations such as crowns, bridges, or dentures. This ensures that the fabricated appliances fit correctly, function harmoniously with the patient's natural dentition, and prevent occlusal interferences.

Question 4

Why is burnout important in the casting process?

Accepted Answer

To remove wax and prepare the mold for casting

Answer

Burnout is a critical step in the lost wax casting technique, where the invested wax pattern is heated in a furnace to high temperatures. This process completely vaporizes the wax, leaving a clean, hollow cavity within the investment mold that precisely replicates the original wax pattern. The empty mold is then ready to receive molten metal, ensuring an accurate and contaminant-free casting for the final restoration.

Question 5

What is the main advantage of using porcelain for dental crowns?

Accepted Answer

Superior aesthetics and translucency

Answer

Porcelain is highly valued in dentistry for its exceptional aesthetic qualities and translucency, allowing it to closely mimic the natural appearance of tooth enamel. This makes porcelain crowns virtually indistinguishable from natural teeth, especially in visible areas of the mouth. While other materials offer strength, porcelain excels in providing a lifelike and aesthetically pleasing restoration.

(CDT) Certified Dental Technicians Practice Test

(CDT) Certified Dental Technicians Practice Test

CDT Dental Materials & Laboratory Techniques