Dental Biomaterials II - Impression Materials Definitions

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What is the primary purpose of a dental impression?

To construct a custom tray for impression materials
To accurately record the dimensions of oral tissues (correct)
To record the fine details of the oral structures
To create a positive replica of the oral tissues

Which type of impression does not register fine details?

Special tray impression
Primary impression (correct)
Stock tray impression
Secondary impression

What is the main function of a dental tray in the context of impressions?

To carry the impression materials into the patient’s mouth (correct)
To record the fine details of oral structures
To provide support to oral tissues
To create a negative replica of teeth

Which material is predominantly used to make stock trays for primary impressions?

Plastic (D) Signup and view all the answers

What is a characteristic requirement of ideal impression materials?

Compatibility with die materials (A) Signup and view all the answers

Among the properties listed, which is NOT a requirement for ideal impression materials?

High flow properties (B) Signup and view all the answers

What is the purpose of Type II tray compound in dentistry?

Act as a support for other impression materials (B) Signup and view all the answers

What is the composition of Type II tray compound mainly made of in terms of percentage?

40% resin and 7% waxes (C) Signup and view all the answers

Which statement best describes the reaction of Type II tray compound upon heating and cooling?

Softens upon heating and hardens upon cooling (B) Signup and view all the answers

How is Type II tray compound manipulated for use?

Softening, loading into the stock tray, followed by insertion, cooling, and impression removal (A) Signup and view all the answers

What is the role of filler in Type II tray compound?

To provide body and suitable working consistency (A) Signup and view all the answers

How does Type II tray compound differ from acrylic special tray?

Type II tray compound is a modeling or tracing material, while acrylic special tray is a support material (C) Signup and view all the answers

Which statement about the thermal properties of impression compounds is correct?

They have low thermal conductivity and a high coefficient of thermal expansion. (D) Signup and view all the answers

Which of the following is NOT a cause of warpage in impression compounds?

Pouring the impression immediately after removal from the mouth (A) Signup and view all the answers

Which property of impression compounds is desirable for their manipulation?

Thermoplastic behavior and sufficient flow at elevated temperatures (B) Signup and view all the answers

What is the recommended technique for softening impression compound sticks?

Holding them above a flame and then tempering in air or warm water (A) Signup and view all the answers

Which of the following is NOT an advantage of impression compounds?

Can reproduce undercuts (C) Signup and view all the answers

What is a potential hygiene concern with the use of impression compounds?

Reusing them without proper disinfection can lead to cross-contamination. (D) Signup and view all the answers

What is the primary function of the inert oil in the base paste of zinc oxide eugenol (ZOE) impression material?

To act as a plasticizer and mask the action of eugenol (D) Signup and view all the answers

What is the role of the catalyst paste (accelerator or reactor) in the setting reaction of ZOE impression material?

It facilitates the formation of the zinc eugenolate chelate (A) Signup and view all the answers

What is the primary chemical reaction involved in the setting of ZOE impression material?

Chelation (C) Signup and view all the answers

Which statement about the manipulation of ZOE impression material is correct?

Mixing can be accomplished in 30-45 seconds until a homogenous mix is formed (D) Signup and view all the answers

What is the primary function of zinc acetate, $MgCl_2$, or $CaCl_2$ in the catalyst paste of ZOE impression material?

To act as a catalyst (accelerator) for the setting reaction (A) Signup and view all the answers

Which statement about the working time of ZOE impression material is correct?

The working time is shortened by the presence of water (B) Signup and view all the answers

What is the initial setting time for Zinc Oxide Eugenol (ZOE) impression paste?

3-5 minutes (B) Signup and view all the answers

How does water, high humidity, and high temperature affect the setting time of ZOE impression material?

Shorten the setting time (A) Signup and view all the answers

What is a factor that accelerates the reaction and setting time of ZOE impression paste?

Adding a drop of water (B) Signup and view all the answers

What is a correct statement about the dimensional changes of ZOE impression material?

Dimensional changes during setting are 0.1% (C) Signup and view all the answers

What is a common use of ZOE impression paste?

Final impression for edentulous patients using border molded acrylic special tray (C) Signup and view all the answers

What material is often used as the model material for ZOE impressions?

Gypsum products (B) Signup and view all the answers