Podcast Beta
Questions and Answers
What is a primary impression?
A stock tray is customized for taking secondary impressions.
False
What is the main purpose of dental impression materials?
To accurately record the dimensions of oral tissues.
A __________ impression is an impression taken for the first time.
Signup and view all the answers
Match the following properties of ideal impression materials:
Signup and view all the answers
Which of the following is NOT an indication for taking an impression?
Signup and view all the answers
Elastic impression materials can be used in areas with undercuts.
Signup and view all the answers
What is the primary use of impression compound?
Signup and view all the answers
The type of impression material that sets by chemical reaction is known as a __________ material.
Signup and view all the answers
Match the type of impression material with its classification:
Signup and view all the answers
Study Notes
Dental Biomaterials II Overview
- Focuses on materials used in dentistry, including impression materials, casting alloys, and dental waxes.
- Key components include dental base polymers and casting procedures.
Impression Materials
- Definition: Dental impression is a negative replica of teeth and oral soft tissues, used for recording dimensions accurately.
-
Types of Impressions:
- Primary Impression: First impression which does not capture fine details.
- Secondary Impression: Taken to capture fine details after the primary impression.
Impression Trays
-
Tray Types:
- Stock Tray: Standardized sizes (1, 2, 3), made of metal or plastic, used for primary impressions.
- Special Tray: Customized on a primary model, made of acrylic or shellac for secondary impressions.
Properties of Ideal Impression Materials
- Ease of manipulation, adequate flow properties, appropriate setting time, good dimensional accuracy, and safety.
- Must be compatible with die and cast materials, have satisfactory odor/taste, be inexpensive, and possess good shelf life.
Classification of Impression Materials
- Classified by:
- Setting Reaction: Chemical (sets by reaction) vs. physical (sets by temperature change).
- Elasticity: Rigid (inelastic) materials for areas without undercuts, and elastic (flexible) materials for all cases.
Rigid (Inelastic) Impression Materials
- Limited to non-undercut areas including:
- Impression compound (thermoplastic).
- Zinc oxide eugenol impression paste (chemical).
- Impression plaster (chemical).
- Impression waxes (physical).
Elastic Impression Materials
- Suitable for both undercut and non-undercut areas:
- Hydrocolloids: Alginate and agar.
- Elastomers: Polysulfide, silicone, and polyether rubber.
Impression Compound
- A thermoplastic material that softens with heat (45-55°C) and hardens when cooled.
- Two types:
- Type I: Low fusing for primary impressions.
- Type II: High fusing for tray material.
- Packaged in cakes or sticks, available in various colors.
Zinc Oxide Eugenol (ZOE) Impression Material
- Rigid material used primarily for secondary impressions in edentulous patients.
- Comprises two pastes: Base paste (white) and catalyst paste (brown/red).
- Setting involves a chelation reaction, resulting in an irreversible bond.
Properties of ZOE
- Initial setting time is 3-5 minutes, final setting under 10 minutes.
- High dimensional stability with minimal changes during setting (0.1%).
- Requires no separating medium for cast preparation.
Non-Eugenol Paste
- Alternative for patients with eugenol allergies, utilizing orthoethoxy benzoic acid derivatives for saponification reaction.
Impression Plaster
- Rarely used due to rigidity and susceptibility to fracture, mainly for mounting casts or recording occlusal bite registrations.
- Supplied as powder mixed with water.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Explore the essential concepts of impression materials used in dentistry, covering types, properties, and tray classifications. Gain insights into primary and secondary impressions, along with the crucial role of dental base polymers and casting procedures.
