30 Questions
What is the primary purpose of a dental impression?
To accurately record the dimensions of oral tissues
Which type of impression does not register fine details?
Primary 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
Which material is predominantly used to make stock trays for primary impressions?
Plastic
What is a characteristic requirement of ideal impression materials?
Compatibility with die materials
Among the properties listed, which is NOT a requirement for ideal impression materials?
High flow properties
What is the purpose of Type II tray compound in dentistry?
Act as a support for other impression materials
What is the composition of Type II tray compound mainly made of in terms of percentage?
40% resin and 7% waxes
Which statement best describes the reaction of Type II tray compound upon heating and cooling?
Softens upon heating and hardens upon cooling
How is Type II tray compound manipulated for use?
Softening, loading into the stock tray, followed by insertion, cooling, and impression removal
What is the role of filler in Type II tray compound?
To provide body and suitable working consistency
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
Which statement about the thermal properties of impression compounds is correct?
They have low thermal conductivity and a high coefficient of thermal expansion.
Which of the following is NOT a cause of warpage in impression compounds?
Pouring the impression immediately after removal from the mouth
Which property of impression compounds is desirable for their manipulation?
Thermoplastic behavior and sufficient flow at elevated temperatures
What is the recommended technique for softening impression compound sticks?
Holding them above a flame and then tempering in air or warm water
Which of the following is NOT an advantage of impression compounds?
Can reproduce undercuts
What is a potential hygiene concern with the use of impression compounds?
Reusing them without proper disinfection can lead to cross-contamination.
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
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
What is the primary chemical reaction involved in the setting of ZOE impression material?
Chelation
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
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
Which statement about the working time of ZOE impression material is correct?
The working time is shortened by the presence of water
What is the initial setting time for Zinc Oxide Eugenol (ZOE) impression paste?
3-5 minutes
How does water, high humidity, and high temperature affect the setting time of ZOE impression material?
Shorten the setting time
What is a factor that accelerates the reaction and setting time of ZOE impression paste?
Adding a drop of water
What is a correct statement about the dimensional changes of ZOE impression material?
Dimensional changes during setting are 0.1%
What is a common use of ZOE impression paste?
Final impression for edentulous patients using border molded acrylic special tray
What material is often used as the model material for ZOE impressions?
Gypsum products
Enhance your understanding of impression materials in dentistry with definitions related to dental impressions and dental impression materials. Learn about the importance of accurately recording the dimensions of oral tissues using different materials.
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