What is an irreversible hydrocolloid?
Irreversible hydrocolloid material used for taking preliminary impressions. Foundation or the basic ingredient of a material. Process of using fingers to contour a closer adaptation of the margins of an impression while still in the mouth. Substance that modifies or increases the rate of a chemical reaction.
What are the advantages and disadvantages of hydrocolloid impression materials?
– Both reversible and irreversible hydrocolloid materials are predominantly water. – Thus, several advantages and disadvantages result when their use is compared with that of other impression materials. – Reversible and irreversible hydrocolloid will wet a tooth surface that is contaminated by oral fluids.
What are the characteristics of hydrocolloid materials?
– Reversible and irreversible hydrocolloid will wet a tooth surface that is contaminated by oral fluids. – Fewer air bubbles are trapped between the tooth and the impression material. – Hydrocolloid materials will even absorb a limited amount of oral fluids. soda pop and fruit juice used to make punch.
How to prevent the evaporation of water from hydrocolloids?
– When the water evaporates, the impression shrinks and is no longer accurate. – To prevent evaporation of water from hydrocolloids (alginate and reversible hydrocolloid), impressions should be poured as soon as possible after disinfecting. – Hydrocolloid materials contract slightly after setting and exude water. – This process is called syneresis.
What material is used in constructing vacuum former?
When taking a facebow registration, should the vertical indicator rod be aligned with the patients?
When mixing gypsum, is it important to use the correct amount of water and powder?
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What type of impression material is commonly used for preliminary impressions?
Sodium alginateSodium alginate is by far the most popular material used to make preliminary impressions. Alginate impression material is also called irreversible hydrocolloid because it is a one‐time use item.
Which irreversible hydrocolloid material is used most widely for preliminary impressions quizlet?
The irreversible hydrocolloid material used most widely for preliminary impressions is: alginate.
Which impression material is the most widely used material?
AlginateAlginate is currently one of the most popular impression materials. It is supplied as dust-free powders. After mixing with proper amount of water in a rubber bowl with a spatula, it is ready for impression taking.
What type of impression tray is required with reversible hydrocolloid impression?
Water-cooled impression traysWater-cooled impression trays are used with reversible hydrocolloid impression materials. These trays feature an interior lining where cold water can be pumped through in order to properly cool the impression material when capturing an impression.
What are the preliminary impressions used to make?
Preliminary impressions are accurate reproductions of a patient's mouth, used for the diagnosis, documentation of dental arches, and visual aid for education.
What are preliminary impressions used to make quizlet?
what are the three classifications of impressions applied in dental procedures? preliminary, final, and occlusal. what is a preliminary impressions used for? to create a reproduction of the teeth and surrounding tissues.
What is irreversible hydrocolloid?
A hydrosol of alginic acid whose physical state is changed by an irreversible chemical reaction, forming insoluble calcium alginate. This substance is called alginate or dental alginate. Alginate is used in dentistry as a primary impression material. Synonym: alginate.
Which of the following is the most widely used dental impression material quizlet?
Which of the following is the most widely used dental impression material? Irreversible hydrocolloid which is alginate.
What is a preliminary impression in dentistry?
Preliminary impressions: Preliminary impressions are used for diagnostic purposes, or as the initial step in the process of fabrication (making) of different prostheses, including crowns and dentures. They're often made at your initial office visit.
Is alginate a reversible hydrocolloid?
The setting involves a chemical reaction. The solid will break down if heated. The solid is not reformed if the alginate is cooled. Consequently, alginate hydrocolloids are called irreversible hydrocolloids.
What type of impression tray is required with reversible hydrocolloid impressions quizlet?
What type of impression tray is required with reversible hydrocolloid impressions? Elastomeric materials use an auto mix system. The extruder gun insert is either catalyst or base.
Why is alginate impression material one of the most common forms used in dentistry?
Alginate impression materials are easy to use, less expensive and have more rapid setting times. The reaction time and therefore the setting time can be controlled with the temperature of the water used.
What is the difference between reversible and irreversible hydrocolloid?
The main difference between Reversible and Irreversible Hydrocolloids is that Irreversible Hydrocolloids set by chemical reaction to reach the Gel state and this process is not reversible, as opposed to Reversible Hydrocolloid that reach the Gel State by means of temperature changes (lowering the temperature).
Which material should be used if a more durable impression material is needed for a bite registration?
ZINC OXIDE EUGENOL (ZOE)-used when a more durable material is needed.
Why would a dentist request preliminary impressions?
There are three primary types of dental impressions: preliminary, final and bite registration: Preliminary impressions: Preliminary impressions are used for diagnostic purposes, or as the initial step in the process of fabrication (making) of different prostheses, including crowns and dentures.
Why should an alginate impression be poured immediately?
When working with alginate impressions, the model should be poured within minutes of when the impression is completed. This is necessary because alginate materials can start to distort after 5 minutes due to dimensional change.
What material is used in constructing vacuum former?
constructing_vacuum former you will use a heavier gauge flexible plastic that does not require a spacer but does require an a
When taking a facebow registration, should the vertical indicator rod be aligned with the patients?
when taking a facebow registration the vertical indicator rod should be aligned with the patients
When mixing gypsum, is it important to use the correct amount of water and powder?
when mixing gypsum it is important to use the correct amount of water and powder its additional powder is added after mixing
What is the filler in most alginate impression materials?
2. The filler in most Alginate Impression materials is a silicate material . Silicate dust causes lung problems if inhaled.
What is an agar impression material?
– Alginate Impression materials set by a chemical reaction that cross-links a carbohydrate polymer. ( Agar impression material )#N#1. Working time is provided by a competing reaction that initially delays cross-linking.#N#When the powder is mixed with water, the alginate powder dissolves, as does the calcium sulfate and sodium phosphate.#N#2. Initially, the calcium ions react with the phosphate ions and precipitate out of solution.#N#The calcium ions do not react with the dissolved alginate until all the phosphate ions have reacted.#N#3. After the retarder (the phosphate ions) has reacted, the setting reaction becomes the#N#dominant reaction.#N#The calcium ions react with the alginate, cross-linking the polymer chains, and gelation#N#occurs.#N#The set material is a hydrogel that is composed mainly of water.
What are the disadvantages of hydrocolloids?
– The disadvantage of the material being predominantly water is that water evaporates from the surface of the impression if it is left exposed to air.# N#– When the water evaporates, the impression shrinks and is no longer accurate.#N#– To prevent evaporation of water from hydrocolloids (alginate and reversible hydrocolloid), impressions should be poured as soon as possible after disinfecting.#N#– Hydrocolloid materials contract slightly after setting and exude water.#N#– This process is called syneresis.#N#– Syneresis occurs very slowly, but it is a second reason to pour hydrocolloid impressions as soon as possible.#N#– When disinfecting a hydrocolloid impression, however, it is important to limit the time that the impression is exposed to an aqueous disinfecting solution.#N#– The hydrocolloid will absorb water, swell, and distort.#N#– This is called imbibition.
Why are alginate impressions called irreversible impressions?
A. Properties. – Alginate Impression materials are termed “irreversible impression materials” because they will not. reverse to the sol state once they react and become a gel. – They have advantages and disadvantages similar to those of reversible hydrocolloid materials because both types of materials are predominantly water.
What is an alginate impression?
Alginate impression material is used for a variety of purposes. It is inexpensive and easy to use but lacks the accuracy for precisely fitting restorations. Proper mixing and handling will result in acceptable study models and casts on which to. fabricate mouth guards and bleaching and fluoride trays.
How is the impression removed?
The impression is removed with a quick motion.
Is soda pop hydrophilic?
of the impression material, which is predominantly water. – Hydrocolloid impression materials are quite hydrophilic, but the same cannot be said for all impression materials.
What material is used in constructing vacuum former?
constructing_vacuum former you will use a heavier gauge flexible plastic that does not require a spacer but does require an a
When taking a facebow registration, should the vertical indicator rod be aligned with the patients?
when taking a facebow registration the vertical indicator rod should be aligned with the patients
When mixing gypsum, is it important to use the correct amount of water and powder?
when mixing gypsum it is important to use the correct amount of water and powder its additional powder is added after mixing