What is elastomer dental?
Elastomeric impression materials (addition silicones and polyethers) offer high elastic recovery and acceptable flexibility on removal of the impression from the mouth. Polyethers are composed of a moderately low- molecular weight polyether, a silica filler and a plasticizer.
What is hysteresis in dentistry?
Hysteresis the property of a material to have two different temperatures for melting and solidifying, unlike water, which has one temperature for both. Syneresis a characteristic of gels to contract and squeeze out some liquid that then accumulates on the surface.
What are elastomeric impression materials used for?
The elastic impression materials are most generally used for the making of impressions for removable partial dentures, immediate dentures, and crowns and fixed partial dentures when tooth and tissue undercuts and surface detail must be recorded with accuracy.
What are dental impression materials?
Impression materials are used to make an accurate replica or mold of the hard and soft oral tissues. The impression is a negative reproduction of the tissues, and by filling the impression with dental stone or other model material, a positive cast is made that can be removed after the model material has set.
What is silicone used for in dentistry?
Silicone, being a more elastic material, allows for more uses for dentists than alginate. With regard to impressions, for example, silicone is used in cases of root canals, soft structures and bone tissues, in addition to implants and functional impressions of full dentures.
What is Imbibition in dental materials?
In dentistry, syneresis is the expulsion of water or other liquid molecules from dental impression materials (alginate for example) after an impression has been taken. The opposite process of syneresis is imbibition, meaning, a material that absorbs water molecules from the surrounding.
What material is used for final impressions?
There are many materials for the final impression, such as gypsum, zinc oxide and eugenol (ZOE) paste, polysulfide rubber, polyether, polyvinyl siloxane, and alginate. Preferences vary much among dentists.
Which material is elastic and reversible?
Elastic impression materials can be further divided into hydrocolloid and elastomeric impression. Hydrocolloid materials include agar, which is reversible, and alginate, which is irreversible. Elastomeric materials include polysulfide, polyether, condensation-cured silicone, and addition-cured silicone.
How are elastomeric impression materials mixed?
elastomeric materials use an Automix system. the extruder gun insert is a dual cartridge with a tube of catalyst and a tube of base. although technique may vary, when assisting a dentist in taking an elastomeric impression, mix the light-bodied material first.
When did they start using elastomers in dentistry?
7. HISTORY After world war II , advances in polymer technology brought to the dental profession a group of synthetic rubbery materials called ELASTOMERS. Polysulfides at the beginning of the fifties (1950), were the first elastomeric impression material used in the world of dentistry. 8.
What are the advantages and disadvantages of elastomers?
Contents Introduction History Elastomers Polysulphide rubber impression material Composition Setting reaction Properties of clinical interest Advantages Disadvantages 3.
How are elastomers used as an impression material?
9. Chemically , there are four kinds of elastomers used as an impression materials :- 1) Polysulphides 2) Condensation -polymerizing silicone 3) Addition -polymerizing silicone 4) Polyether 10. According to viscosity they are classified as Light body Medium body / Regular body Heavy body Putty
What can an unlicensed dental assistant do in a dental office?
Answer: An unlicensed dental assistant may perform such tasks as: preparing the patient for treatment by seating patient, obtaining records and applying protective garb; performing solely mechanical work upon inert matter in a dental office, e.g. trimming or mounting impressions taken by the dentist.