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disadvantages of elastomeric impression materials

Non-aqueous elastomeric impression materials include polysulfide, polyether, condensation silicone, and addition silicone (vinyl polysiloxane). Base paste (white) Accelerator (brown/grey) Available in 3 viscosities: Light bodied; Medium bodied; Heavy bodied; Composition: Base paste: • Putty consistency is supplied in jar. 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 . Recently, new elastomeric impression materials have been introduced, with the claim of very high elastic recovery and high tear and tensile strengths. Br Dent J 121:277, 1966. True False . The differences between impression materials, as outlined above, are the materials themselves and the purpose they are used for. Purpose: This study investigates the modulus of elasticity, yield strength, the strain at yield point, and the tear energy of nine elastomeric 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. Br Dent J 151:179, 1981. PolysulFide This was first elastomeric impression material to be introduced. 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. • 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 . Elastomeric impression materials offer high elastic recovery and acceptable flexibility on removal of the impression from the mouth . Polyvinyl siloxane and polyether impression materials remain dimensionally accurate … Author: R Gibbons, RDN, PTTLS It was the first type of silicone impression material. er efore, the impression technique needs to be modi ed. The operating principle involves the application of a fixed compressive strain and the resulting stress is measured. Silicone Elastomeric Impression materials + Dental Materials No comments. Indicates having elastic or rubber like qualities. Composition: Base paste. Elastomeric. Current-generation elastomeric impression materials and digital scanners are capable of quickly and accurately capturing prepared teeth. Setting occurs in room temp , so called as RTV silicones. Impression Materials A. True False . Supplied as. – They are clean and do not have an unpleasant taste or smell. they often require special equipment to prepare. These are high precision and essential for impressions that will be used for the fabrica-tion of indirect restorations and laboratory fabricated aligners. – Addition silicone impression materials are a lso called vinyl polysiloxanes and McCabe, J. F., and Bowman, A. J.: The rheological properties of dental impression materials. As the residual ridges resorb, the tissues become unsupported and displaceable; the use of conventional impression techniques will result in a distorted impression. It is also known as Mercaptan or Thiokol. silicone → This is the most popular type of elastomeric impression material. (b) Disadvantages – The disadvantage … – Hydrocolloid impression materials are quite hydrophilic, but the same cannot be said for all impression materials. Also known as conventional silicones. But for elastomeric impression materials these methods have proven to be ineffective as they do not prevent cross contamination among the dental team. 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. (ZOE) or elastomeric impression materials because of the inherent accuracy of these materials and their propensity to distribute pressure equally [ ]. 3- Heavy body. Available as 1- Light body. Wilson, H. J.; Elastomeric impression materials. True False . non aqueous elastomeric impression materials. ELASTOMERIC IMPRESSION MATERIALS The impression materials discussed so far are not good enough generally for taking accurate impressions of the dental patient. It is found that to record fine detail viscosity should be lower. pouring the impression with gypsum products is easier than with elastomeric impression materials. 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. 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 … 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. – Few dentists use reversible hydrocolloid, but those who do, love it. Purpose. 5. This instrument has been called a Comprheometer. brittle → ZOE is ___ in texture when dried or set. Conclusion: Overall contemporary retraction materials showed low potential for polymerization inhibition of elastomeric impression materials. 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. Viscosity is also an important property of a material for the precise impression in a cast. Nonaqueous Elastomeric Impression Materials-commonly known as "rubber" impression materials, includes:-Polysulfide-Condensation silicone-Addition silicone-Polyether. These supporting structures include gingiva, a lveolar bone or residual ridge, hard and soft palate, and frenums, which are muscle attachments. – They are the most accurate, stable, and expensive impression materials. 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. -disadvantages = complex prep. 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. Learn vocabulary, terms, and more with flashcards, games, and other study tools. # Disadvantage of polysulfide as an impression material : A. 2- Medium body. • Regardless of type all elastomeric impression materials are supplied as two paste system (base and catalyst) in collapsible tubes. In 1989, Peutzfeldt and Amusen studied the accuracies of alginate and elastometric impression materials. General Comments – Impression materials are used to make replicas (models or casts) of t eeth and other oral tissues. PVS impression materials can make details of even 1 to 2μm. The trueness and precision of the digitization of these new elastomeric impression materials are unclear. 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. CONDENSATION SILICONES. – Again, the gypsum product, when mixed with water, easily wets the surface of the impression material, which is predominantly water. 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 … – In dentistry, we take impressions of teeth and their supporting structur es. Nonaqueous elastomeric → Materials that set hard or rigid are known as what types of impression material? Start studying impression materials elastomers. 13. Addition Silicones – Addition silicones are the most popular type of elastomeric impression mat erial, especially for crown and bridge impressions. 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. The visco-elastic properties of a number of set elastomeric impression materials were determined using a torsional pendulum apparatus i.e. One of the disadvantages of the silicone impression materials (including condensation silicones) is their inherent hydrophobic nature. 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. 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 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. This paper describes the development of an instrument for determining consistency, working time and setting time of elastomeric impression materials. Elastomeric impression materials have been marketed for optimizing direct digital acquisition without requiring a stone cast. 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. elastomeric impression materials must be able to reproduce fine detail of 25 μm or less. Types of elastomeric impression materials Composition Setting reaction Advantages and disadvantages #NEETMDS #dentistry #dentalmaterials An electronic search of the Scopus and PubMed databases was performed in November 2010. 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. : a technique needs to be ineffective as they do not prevent cross contamination the. To record fine detail viscosity should be lower fixed compressive strain and the purpose they are clean do!, especially for crown and bridge impressions proven to be introduced or casts ) t... 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