Impression Techniques for Dentures

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Questions and Answers

What type of impression materials can be used as secondary impression materials for complete dentures?

Liquid silicone

Alginates

Metallic oxide pastes (correct)

Polyether materials

Why should metallic oxide pastes not be used in stock impression trays?

They can expand and distort the impression.

They only work with custom trays.

They are rigid and do not adapt well. (correct)

They are too flexible and cannot hold their shape.

What condition must be met for metallic oxide pastes to be used effectively?

The impression tray should always be disposable.

The impression tray must be made of metal.

The impression tray must be filled with a soft lining material.

The impression tray must be properly designed and attached to the framework. (correct)

In what scenario are metallic oxide pastes NOT used?

In stock impression trays. Signup and view all the answers

Which impression materials are suitable for use with a custom acrylic impression tray?

Metallic oxide pastes and alginate Signup and view all the answers

What is a disadvantage of the conventional technique in impression making?

It may show tissue movement under occlusal load in free end saddle dentures. Signup and view all the answers

Which impressions are best suited for Kennedy class III and IV dentures?

Mucostatic technique impressions Signup and view all the answers

How does the conventional technique for impression making differ in its application?

It captures the ridge at its resting form without occlusal load. Signup and view all the answers

Which of the following options is NOT a selective pressure technique?

Anatomical technique Signup and view all the answers

What impression material is typically used in the conventional mucostatic technique?

Soft or less viscous alginate Signup and view all the answers

What is the most critical time frame to prevent volume change after removing an impression from the mouth?

15 minutes Signup and view all the answers

How do exudates from hydrocolloid affect gypsum products?

They cause a retarding effect on the chemical reaction. Signup and view all the answers

What is the result of the retarding effect caused by exudates from hydrocolloid on gypsum products?

A chalky cast surface Signup and view all the answers

When should adjustments to the impression be made to ensure the best results?

Within 15 minutes after removal Signup and view all the answers

What kind of surface does a chalky cast indicate concerning the impression process?

Retarded chemical reaction Signup and view all the answers

Where should the material be placed when making a maxillary impression?

In the highest aspect of the palate and over the rugae Signup and view all the answers

What tool should be used to help retract the cheek during the maxillary impression process?

A mouth mirror or index finger Signup and view all the answers

When the tray is being rotated into the mouth, from which side should this be done?

From the side opposite to the cheek being retracted Signup and view all the answers

What is the primary reason for placing material over the rugae during an impression?

To ensure a more accurate fit of the denture Signup and view all the answers

What is the effect of not properly retracting the cheek during a maxillary impression?

Inaccurate impression details Signup and view all the answers

What is the primary reason for ensuring that the tray does not move during gelation?

To avoid inaccurate impressions Signup and view all the answers

What could result if movement of the tray is allowed during the impression procedure?

Introduction of internal stresses Signup and view all the answers

Who is likely to cause movement of the tray during the gelation process?

The patient or assistant Signup and view all the answers

What is a consequence of an inaccurate impression due to tray movement?

Potential fitting issues for final appliances Signup and view all the answers

During the impression procedure, what practice should be avoided in relation to the tray?

Allowing any assistance from others to hold the tray Signup and view all the answers

Study Notes

Conventional Impression Technique

Records the resting form of the ridge without occlusal load.
Uses soft or less viscous alginate impression material.
Suitable for tooth-supported partial dentures (Kennedy Class III and IV).
Not recommended for free-end saddle dentures due to potential tissue ward movement.
Not to be used with stock impression trays.

Metallic Oxide Pastes

Can be used as secondary impression materials for complete dentures.
Used for extension base edentulous areas with custom acrylic impression trays.
Trays must be properly designed and attached to the partial denture framework.
Need to be poured within 15 minutes after removal from the mouth to prevent volume change.

Hydrocolloid Exudates

Have a retarding effect on gypsum products, resulting in a chalky cast surface.

Impression Making Tips

When making a maxillary impression, place the material in the highest aspect of the palate and over the rugae.
Use a mouth mirror or index finger to retract the cheek on the side away from you while rotating the tray into the mouth.
Avoid tray movement during gelation to prevent internal stresses and an inaccurate impression.
Do not allow the patient or an assistant to hold the tray in position.

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Description

This quiz covers various impression techniques used in dentistry, including conventional methods, metallic oxide pastes, and hydrocolloid exudates. It highlights their applications, advantages, and specific considerations necessary for making effective dental impressions. Ideal for dental students and professionals looking to enhance their understanding of impression materials.