ELASTOMERIC IMPRESSION MATERIALS The impression materials discussed so far are not good enough generally for taking accurate impressions of the dental patient. True False . High cost B. materials leaching out C. Stretching leads to distortion D. Difficulty in cast pouring # Hydrocolloid material shows all except : A. Hysteresis B. Imbibition C. Recrystallization D. Syneresis # Impression material which has a high incidence of air porosity is : A. Alginate impression material B. Recently, new elastomeric impression materials have been introduced, with the claim of very high elastic recovery and high tear and tensile strengths. non aqueous elastomeric impression materials. Available as 1- Light body. The operating principle involves the application of a fixed compressive strain and the resulting stress is measured. -disadvantages = complex prep. • Putty consistency is supplied in jar. These supporting structures include gingiva, a lveolar bone or residual ridge, hard and soft palate, and frenums, which are muscle attachments. Author: R Gibbons, RDN, PTTLS pouring the impression with gypsum products is easier than with elastomeric impression materials. True False . they often require special equipment to prepare. – They are the most accurate, stable, and expensive impression materials. A nonionic surfactant can be added to the paste in the manufacturing process to render a degree of hydrophilicity to the surface of the material. Conclusion: Overall contemporary retraction materials showed low potential for polymerization inhibition of elastomeric impression materials. True False . Elastomeric impression materials offer high elastic recovery and acceptable flexibility on removal of the impression from the mouth . Wilson, H. J.; Elastomeric impression materials. An electronic search of the Scopus and PubMed databases was performed in November 2010. Popularity of Reversible Hydrocolloid ( Agar ) – With the various advantages and disadvantages of reversible hydrocolloid material, one would expect dentistry to have a love–hate relationship with this material. 3- Heavy body. The visco-elastic properties of a number of set elastomeric impression materials were determined using a torsional pendulum apparatus i.e. Materials and methods: The values of the first three variables were computed from a tensile load test of 10 dumbbell-shaped specimens of each impression material. Current-generation elastomeric impression materials and digital scanners are capable of quickly and accurately capturing prepared teeth. Br Dent J 151:179, 1981. Therefore, the alginate impression materials may have the same degrees of accuracy as those of elastomeric impression materials but, in reality, alginate impression materials still perform more poorly than rubber base impression materials. (ZOE) or elastomeric impression materials because of the inherent accuracy of these materials and their propensity to distribute pressure equally [ ]. PolysulFide This was first elastomeric impression material to be introduced. • Disadvantages – Does not reproduce fine detail as reliably as other elastomeric impression materials – Dimensional stability is poor – Must be poured immediately to prevent distortion Packaging • Powder packaged in bulk – Sealed screw top plastic container or hermetically sealed metal can . What are the disadvantages of elastomeric impression materials?-strong sulfuric odor and bad taste -staining of clothes -setting time is ten min-water,saliva and blood affect setting time -glove powder can contaminate impression. Purpose: This study investigates the modulus of elasticity, yield strength, the strain at yield point, and the tear energy of nine elastomeric impression materials. It was the first type of silicone impression material. Base paste (white) Accelerator (brown/grey) Available in 3 viscosities: Light bodied; Medium bodied; Heavy bodied; Composition: Base paste: Setting occurs in room temp , so called as RTV silicones. Mechanical properties of elastomeric impression materials (H LU, B NGUYEN - 2004 ) Mechanical properties of three commercial elastomeric impression materials two addition silicone impression materials and one polyether material with low and high viscosities were compared. Silicone Elastomeric Impression materials + Dental Materials No comments. elastomeric impression materials must be able to reproduce fine detail of 25 μm or less. – They are clean and do not have an unpleasant taste or smell. With elastomeric impression materials such as polyvinyl siloxane, polyether, and polysulfide, the dimensional accuracy is usually time dependent, with greater dimensional accuracy occurring immediately after polymerization is complete but declining as the impression is stored for extended periods of time . – Hydrocolloid impression materials are quite hydrophilic, but the same cannot be said for all impression materials. POLYSULFIDE ELASTOMERIC IMPRESSION MATERIAL: First elastomeric impression material to be introduced, also known as mercaptan / thymol, it is a type of Rubber based impression material. This instrument has been called a Comprheometer. # Disadvantage of polysulfide as an impression material : A. As the residual ridges resorb, the tissues become unsupported and displaceable; the use of conventional impression techniques will result in a distorted impression. This paper describes the development of an instrument for determining consistency, working time and setting time of elastomeric impression materials. Addition Silicones – Addition silicones are the most popular type of elastomeric impression mat erial, especially for crown and bridge impressions. CONDENSATION SILICONES. (b) Disadvantages – The disadvantage … Composition: Base paste. One of the disadvantages of the silicone impression materials (including condensation silicones) is their inherent hydrophobic nature. Nonaqueous Elastomeric Impression Materials-commonly known as "rubber" impression materials, includes:-Polysulfide-Condensation silicone-Addition silicone-Polyether. Elastomeric. Perhaps the greatest challenge clinicians face while capturing an impression is achieving complete reproduction of the prepared finish line, particularly with sub- or equigingival margins. Nonaqueous elastomeric → Materials that set hard or rigid are known as what types of impression material? Indicates having elastic or rubber like qualities. In 1989, Peutzfeldt and Amusen studied the accuracies of alginate and elastometric impression materials. Br Dent J 121:277, 1966. Viscosity is also an important property of a material for the precise impression in a cast. Impression Materials A. 2- Medium body. brittle → ZOE is ___ in texture when dried or set. 13. – Few dentists use reversible hydrocolloid, but those who do, love it. McCabe, J. F., and Bowman, A. J.: The rheological properties of dental impression materials. elastomeric impression materials on repeated pours would suggest that addition silicones and polyethers to a certain extent were least affected with delay in pouring the impression. Research Article Mechanical Properties of Elastomeric Impression Materials: An In Vitro Comparison DinoRe, 1 FrancescoDeAngelis, 2 GabrieleAugusti, 1 DavideAugusti, 1 SergioCaputi, 2 MaurizioD Amario, 3 andCamilloD Arcangelo 2 Department of Oral Rehabilitation, Istituto Stomatologico Italiano, University of Milan, Milan, Italy – Again, the gypsum product, when mixed with water, easily wets the surface of the impression material, which is predominantly water. Non-aqueous elastomeric impression materials include polysulfide, polyether, condensation silicone, and addition silicone (vinyl polysiloxane). Elastomeric impression materials have been marketed for optimizing direct digital acquisition without requiring a stone cast. The trueness and precision of the digitization of these new elastomeric impression materials are unclear. It is found that to record fine detail viscosity should be lower. – Addition silicone impression materials are a lso called vinyl polysiloxanes and 5. silicone → This is the most popular type of elastomeric impression material. Start studying impression materials elastomers. The purpose of this in vitro study was to compare the trueness and precision of digital dental casts obtained from the direct digitization of 2 … Also known as conventional silicones. Disadvantages of reversible Hydrocolloid-A lot of equipment -Inaccurate and distorted impression when the tray is removed from the mouth too soon, improper removal or inadequate amount of material in tray.-Grainy material caused by insufficient boiling or keeping the storage temperature too low. The aim of the present paper was to review the literature concerning the dimensional stability of dental elastomeric impression materials, to support recommendations to control the variables that influence the accuracy of these materials. elastomeric materials: silicones (polyvinyl siloxane): condensation-cured silicones, addition silicones, vinyl polyether silicones (VPES) polyethers ; polysulphides; rigid materials: plaster of Paris; impression compound; zinc oxide and eugenol-based impression paste; Techniques for taking impression. Polyvinyl siloxane and polyether impression materials remain dimensionally accurate … Learn vocabulary, terms, and more with flashcards, games, and other study tools. Each of the materials has advantages and disadvantages, but they are each used for a different purpose and are effective and commonly used products in dentistry today. It is also known as Mercaptan or Thiokol. – In dentistry, we take impressions of teeth and their supporting structur es. Types of elastomeric impression materials Composition Setting reaction Advantages and disadvantages #NEETMDS #dentistry #dentalmaterials But for elastomeric impression materials these methods have proven to be ineffective as they do not prevent cross contamination among the dental team. Supplied as. These are high precision and essential for impressions that will be used for the fabrica-tion of indirect restorations and laboratory fabricated aligners. er efore, the impression technique needs to be modi ed. PVS impression materials can make details of even 1 to 2μm. Reprint requests to: DR. J. F. MCCABE UNIVERSITY OF NEWCASTLE UPON TYNE THE DENTAL SCHOOL FRAMLINGTON PLACE NEWCASTLE L'PON TYNE NE2 4BW ENGLAND 104 JANUARY 1985 VOtUME … Purpose. General Comments – Impression materials are used to make replicas (models or casts) of t eeth and other oral tissues. 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