Podcast
Questions and Answers
The function of an impression material is to accurately record the dimensions of oral tissues and their spatial ______.
The function of an impression material is to accurately record the dimensions of oral tissues and their spatial ______.
relationships
A positive reproduction obtained from an impression is referred to as a ______ when large areas of oral tissues are involved.
A positive reproduction obtained from an impression is referred to as a ______ when large areas of oral tissues are involved.
model
Thermoplastic impression materials soften under heat and solidify when ______.
Thermoplastic impression materials soften under heat and solidify when ______.
cooled
An individual tray is a self-made tray created specifically for one ______.
An individual tray is a self-made tray created specifically for one ______.
Type I dental gypsum is an example of a ______ impression material that hardens by chemical reaction.
Type I dental gypsum is an example of a ______ impression material that hardens by chemical reaction.
Impression plasters are plasters of Paris to which ______ have been added to regulate the setting time.
Impression plasters are plasters of Paris to which ______ have been added to regulate the setting time.
The W:P ratio for manipulating impression plasters is typically between ______ and 0.7.
The W:P ratio for manipulating impression plasters is typically between ______ and 0.7.
To facilitate easy removal of the cast, a coat of ______ should be painted onto the impression plaster before pouring in gypsum.
To facilitate easy removal of the cast, a coat of ______ should be painted onto the impression plaster before pouring in gypsum.
The maximum setting time for impression plaster is typically between ______ and 5 minutes.
The maximum setting time for impression plaster is typically between ______ and 5 minutes.
Type II impression compound is also known as ______ compound.
Type II impression compound is also known as ______ compound.
Flashcards are hidden until you start studying
Study Notes
Impression Materials Overview
- Impression materials capture the dimensions and spatial relationships of oral tissues.
- The negative impression obtained is used to create a positive model or cast by pouring dental stone or similar material.
Types of Impressions
- Preliminary Impression: Initial impression for study cast development.
- Secondary/Final/Wash Impression: Corrective impressions for master or working cast creation for prosthesis.
Classification by Use in Dentistry
- Restorative Dentistry: Does not use modeling compound impression materials.
- Prosthodontics: Involves creating prosthetic devices.
- Orthodontics: Focuses on dental alignment and braces.
Classification by Manner of Hardening
- Thermoplastic Impression Materials:
- Softens with heat and solidifies upon cooling; no chemical change during this process.
- Examples: modeling compound, agar, waxes.
- Thermoset Impression Materials:
- Hardens via chemical reaction upon mixing.
- Examples: dental gypsum (Type I), alginate, rubber materials (polysulfide, silicone, polyether), zinc oxide eugenol pastes.
Types of Impression Materials
- Rigid Impression Materials: Hardens upon removal; used in edentulous mouths without undercuts.
- Examples: modeling compound, impression plaster, zinc oxide eugenol paste.
- Elastic Impression Materials: Flexible upon removal, suitable for areas with undercuts.
- Examples: alginate, agar, rubber impression materials.
Impression Trays
- Stock Trays: Pre-manufactured trays.
- Non-perforated: For modeling compound.
- Rim-locked: Added retention for impression material.
- Perforated: Enhances retention and pressure release.
- Individual Trays: Custom-made trays tailored to the patient's mouth using acrylic or shellac.
- Water-Cooled Tray: Specifically designed for agar impression material.
Impression Plaster
- Hardly used due to rigidity and fragility but valued for short setting times.
- Primarily for mounting casts or occlusal bite registrations, classified as thermoset and rigid.
- Color: Light pink.
- Composition includes CaSO4·2H2O, and potato starch for easy removal post-setting.
Manipulation of Impression Plaster
- Mix using a plaster bowl at a water-to-powder ratio of 0.6-0.7.
- Increase water to reduce exothermic heat during mixing.
- Setting time ranges from 3 to 5 minutes.
- Withdraw carefully from the mouth with a teasing motion to avoid fracture.
Casting and Separation Techniques
- Apply a separating medium (Colorgard) to the impression before pouring the gypsum cast.
- Allow the cast to set for 30–60 minutes before separation.
- Submerging in hot water aids in the de-molding process.
Modeling Compound Types
- Type I: Low fusing compound, softens at 55-65°C; often used for final impressions or check impressions.
- Type II: Tray compound tailored for specific applications.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
