Prosthetic Dentistry: Impression Trays

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Questions and Answers

What is the function of the spacer in a custom tray?

To stabilize the tray in the mouth

To properly position the tray during border molding procedure (correct)

To provide support for the lip while making impression

To prevent distortion of the material at the final stage

What is the purpose of applying separating media on the cast?

To prevent acrylic resin from sticking to the cast (correct)

To ensure smoothness of the exposed surfaces of the tray

To provide relief in specific areas of the oral structures

To adapt wax over relief areas marked on the cast

What is the recommended distance from the sulcus to the handle in fabricating a handle for a custom tray?

2 cm (correct)

1 cm

3 cm

4 cm

When should trays be sterilized?

Before use on patients Signup and view all the answers

What is the function of a tray handle?

Supports the lip while making impression Signup and view all the answers

What should be done with undercuts on the primary cast?

They should be blocked out Signup and view all the answers

What should be done with sharp corners or edges on a custom tray?

They should not exist as they would hurt the patient Signup and view all the answers

Why are disposable trays recommended?

To prevent cross-contamination between patients Signup and view all the answers

What is the purpose of an impression tray in dentistry?

To carry, confine & control the impression material in the patient's mouth Signup and view all the answers

What are the requirements of an impression tray?

The tray should retain its shape throughout the impression procedure and while pouring stone on the impression Signup and view all the answers

What is the recommended border extension of an impression tray?

2mm short of the vestibular depth with no interference with muscle or frenal attachment Signup and view all the answers

What should be the handle design of an impression tray?

Angulated to exclude the lips Signup and view all the answers

Which material can be used to fabricate metallic trays?

(stainless steel, Aluminum) Signup and view all the answers

What is a dental impression?

A negative imprint of hard and soft tissues from which a positive reproduction can be formed. Signup and view all the answers

What is the main difference between stock trays and custom trays?

Stock trays are ready-made and come in specific sizes, while custom trays are fabricated based on a particular patient's cast. Signup and view all the answers

What factors affect the selection of stock trays?

The type of mouth, type of impression material, size of the arch, and the form of the arch. Signup and view all the answers

What is the purpose of stock trays?

To carry impression material to the mouth and support it during polymerization. Signup and view all the answers

What are custom trays made from?

Metallic or non-metallic materials such as cold cure acrylic resin, hot cure acrylic resin, or light cure acrylic resin. Signup and view all the answers

What determines the material choice for custom trays?

Fabrication time, material properties, and hazardous effects. Signup and view all the answers

What do spacer and stop trays use to provide extra space for impression material with higher viscosity?

A wax spacer. Signup and view all the answers

Study Notes

According to the method of fabrication, there are stock trays and custom trays or special trays for making dental impressions.
Stock trays are ready-made and come in specific sizes, while custom trays are fabricated based on a particular patient's cast.
Stock trays are reusable after sterilization, while custom trays are unique to the patient and discarded.
Stock trays serve to carry impression material to the mouth and support it during polymerization. They are available in different materials and sizes.
Factors affecting selection of stock trays include the type of mouth, type of impression material, size of the arch, and the form of the arch.
Custom trays are made from a cast recovered from primary impression and used to make a final impression. They are more accurate and comfortable for the patient.
Custom trays can be made of metallic or non-metallic materials, such as cold cure acrylic resin, hot cure acrylic resin, or light cure acrylic resin.
The material choice for custom trays depends on various factors such as fabrication time, material properties, and hazardous effects.
Close-fit trays are directly adapted to the cast, while spacer and stop trays use a wax spacer to provide extra space for impression material with higher viscosity.
Criteria for special tray construction include not impinging on movable structures, extending borders beyond the vestibular sulcus, and ensuring sufficient rigidity and thickness.

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Description

Test your knowledge about dental impression trays and their use in prosthetic dentistry with this quiz. Learn about the definition and purpose of dental impressions and impression trays in creating positive reproductions of teeth and soft tissues.