Podcast
Questions and Answers
What is the recommended mixing time for putty by hand to achieve a streak-free mix?
What is the recommended mixing time for putty by hand to achieve a streak-free mix?
- 1 minute
- 15 seconds
- 2 minutes
- 30 seconds (correct)
Vinyl gloves can be used when handling putty material.
Vinyl gloves can be used when handling putty material.
True (A)
Which type of zinc oxide-eugenol (ZOE) impression is suitable for an edentulous mouth?
Which type of zinc oxide-eugenol (ZOE) impression is suitable for an edentulous mouth?
- Type II - Soft set (correct)
- Type I - Hard set
- Final impression for a dentate mouth
- Type III - Temporary set
What is the maximum setting time for putty at a temperature of 37°C?
What is the maximum setting time for putty at a temperature of 37°C?
The __________ should be held firmly until the wash material sets.
The __________ should be held firmly until the wash material sets.
Type I ZOE impressions have a setting time of 10 minutes for fast set.
Type I ZOE impressions have a setting time of 10 minutes for fast set.
What is the primary use of ZOE as a relining material?
What is the primary use of ZOE as a relining material?
Match the following components with their roles in the putty-wash system:
Match the following components with their roles in the putty-wash system:
The catalyst in ZOE impressions helps to speed up the ______.
The catalyst in ZOE impressions helps to speed up the ______.
Match the components of ZOE with their functions:
Match the components of ZOE with their functions:
What is the proper proportion for mixing ZOE paste?
What is the proper proportion for mixing ZOE paste?
Eugenol is used in ZOE impressions to enhance flow properties.
Eugenol is used in ZOE impressions to enhance flow properties.
What is the primary purpose of fillers in hydrocolloids?
What is the primary purpose of fillers in hydrocolloids?
Name a plasticizer used in ZOE impressions.
Name a plasticizer used in ZOE impressions.
Syringe material for reversible hydrocolloids has a higher strength compared to tray material.
Syringe material for reversible hydrocolloids has a higher strength compared to tray material.
What is the role of glycerine in reversible hydrocolloids?
What is the role of glycerine in reversible hydrocolloids?
The tray material should be tempered to _____ in the third water bath before making impressions.
The tray material should be tempered to _____ in the third water bath before making impressions.
Which temperature is used to convert agar to sol in the hydrocolloid conditioner?
Which temperature is used to convert agar to sol in the hydrocolloid conditioner?
What is the primary characteristic of dimensional stability in impression materials?
What is the primary characteristic of dimensional stability in impression materials?
What is the recommended manner of withdrawal for taking impressions?
What is the recommended manner of withdrawal for taking impressions?
The tear strength of the tray type material is _____ lb/in².
The tear strength of the tray type material is _____ lb/in².
Irreversible hydrocolloids can be converted back to a sol once they have gelled.
Irreversible hydrocolloids can be converted back to a sol once they have gelled.
Match the material with its property or usage:
Match the material with its property or usage:
What is the main ingredient by weight in reversible hydrocolloid materials?
What is the main ingredient by weight in reversible hydrocolloid materials?
Agar is derived from certain types of ______.
Agar is derived from certain types of ______.
Match the reversible hydrocolloid components with their functions:
Match the reversible hydrocolloid components with their functions:
What is the gelation temperature of agar?
What is the gelation temperature of agar?
Agar was the first successful elastic impression material used in dentistry.
Agar was the first successful elastic impression material used in dentistry.
What is a common use for reversible hydrocolloids in dentistry?
What is a common use for reversible hydrocolloids in dentistry?
What is the main advantage of the syringe technique in impression taking?
What is the main advantage of the syringe technique in impression taking?
The tear strength of RIM is less than that of hydrocolloids.
The tear strength of RIM is less than that of hydrocolloids.
How should an impression be removed from a patient's mouth?
How should an impression be removed from a patient's mouth?
Polysulfide RIM has a dimensional contraction of _____ during the first 24 hours.
Polysulfide RIM has a dimensional contraction of _____ during the first 24 hours.
Match the following types of RIM with their respective dimensional stability:
Match the following types of RIM with their respective dimensional stability:
Which of the following factors can control the setting time of RIM?
Which of the following factors can control the setting time of RIM?
The use of oleic acid in the mixture will accelerate curing.
The use of oleic acid in the mixture will accelerate curing.
What is the recommended action after removing an impression from the patient's mouth?
What is the recommended action after removing an impression from the patient's mouth?
Study Notes
ZOE (Zinc Oxide-Eugenol) Impressions
- Used as a thin layer in trays for wash impressions; thermoset and rigid, ineffective for undercuts.
- Composed of a two-paste system:
- Base paste (white)
- Catalyst paste (brown/amber).
- Applications include final impressions for edentulous mouths, denture relining, centric jaw registration, cementing, and temporary filling.
- Types classified by setting properties:
- Type I: Hard set (3-6 min initial setting time, 10 min final setting time).
- Type II: Soft set (3-6 min initial, 15 min final).
- Key Components of Base Paste:
- Finely divided zinc oxide with minimal water and inert oil for plasticity.
- Hydrogenated rosin enhances thermoplasticity.
- Catalyst contains oil of cloves (eugenol substitute) for reduced irritation, polymerized rosin for smoothness, and various accelerators to adjust setting times.
Hydrocolloid Impression Materials
- Elastic materials that deform when removed, regaining original shape for accurate impressions.
- Hydrocolloids transition between sol (liquid) and gel (solid) states based on temperature.
- Two types:
- Reversible hydrocolloids (change back to sol).
- Irreversible hydrocolloids (permanent gel).
- Agar is the primary component in reversible hydrocolloids, derived from seaweed.
- Requires specific manipulation techniques, including single and double impression methods.
Manipulation Techniques
- For reversible hydrocolloids, agar is heated and cooled in controlled water baths for optimal sol/gel transformation.
- Double Impression Technique: A weaker syringe material is used first, followed by a stronger tray material.
- Accurate removal requires a sudden motion to prevent deformation.
Properties of Reversible Hydrocolloids
- Compressive strength varies, with tray materials offering maximum strength.
- Must be kept at ideal temperatures to maintain fluidity and prevent burns to oral tissues.
- Final impressions should not be submerged in water or exposed to direct sunlight.
Polyether and Polysulfide RIM (Rubber Impression Materials)
- Polyether materials require steady removal forces to maintain impression integrity.
- Setting time influenced by temperature; increasing temperature shortens time, while lowering it extends time.
- Polysulfide and silicone materials exhibit superior elasticity, strength, and dimensional stability compared to hydrocolloids.
Key Properties of RIM
- Excellent elasticity, allowing minimal permanent deformation under strain.
- High tear strength in comparison to hydrocolloids: polysulfide RIM offers the best performance.
- Low shrinkage percentages indicate superior dimensional stability during curing.
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Description
This quiz explores the procedures involved in mixing dental putty with a catalyst for impression making. Understand the importance of proper mixing techniques and the role of moisture during the process. Test your knowledge on the steps required for achieving optimal results in dental impressions.