The properties of impression plasters can be compared with those of model plasters and stones by reference to Table 3.2. Non-elastic materials are generally not used for taking impressions of crown preparations because of their inability to accurately record undercuts. Agar may be used but as discussed has a number of technical difficulties in its use. 2/23/2016 17. Dentaljuce and Prosthodontics - this should go together well. Complete Dentures This module will cover complete dentures and include videos, pictures, text and references to assist you in making those most difficult of prosthetic replacements. The mix should be a smooth paste, free of air bubbles, which may appear on the surface of the impression leading to inaccuracy. 5. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. The materials are poor conductors of heat and it may take several minutes for the centre of the material to become softened. Non elastic impression materials 1. Potassium sulphate is the most common of these and has the secondary effect of accelerating the setting reaction, details of which are discussed on p. 37. 20 C. 21 D. 26 # During setting of alginate impression materials: A. Trisodium phosphate reacts with Sodium alginate B. Trisodium phosphate reacts with calcium sulphate C. Colloidal gel changes to sol Elastic impression materials can be further divided into hydrocolloid and elastomeric impression. Both the temperature and time of conditioning in the water bath affect the performance of the material. Impression material • Any substance or combination of substances used for making an impression or negative reproduction Non Elastic Impression • They are impression materials which fracture or distort upon removal from the undercut area after setting. As an alternative an anti-expansion solution, containing potassium sulphate, borax and pigment, may be prepared and used with a standard white plaster. While in the mouth they set in a reasonable amount of time. BDS. Regardless of the topic, subject or complexity, we can help you write any paper! Impression plaster. If you continue browsing the site, you agree to the use of cookies on this website. If you continue browsing the site, you agree to the use of cookies on this website. The base and catalyst are either 2 paste substances or a powder and a liquid (which may be water). The conditioning time must also be carefully monitored. 1. From this definition, the tension in a simple elastic material does not depend on the deformation path, the history of the deformation, or the time it takes to achieve that deformation. A temperature in the range 55–60°C is normally found to be ideal. As stated above, there are times clinically where the accuracy of an alginate impression is not acceptable, particularly for the construction of fixed prosthodontics. It consists of calcined, β-calcium sulphate hemihydrate which when mixed with water reacts to form calcium sulphate dihydrate. Rigid Impression Materials. This definition also implies that the constitutive equations are spatially local. Elastic. Impression types; Non-Elastic Materials; Prosthodontics. Elastic impression materials 1. Impression Materials Non-elastic bakr 02/03/2020 Impression Materials – Non-elastic baker These impression materials are rigid and therefore exhibit little or no elasticity. -Must be stored in an airtight container . See our Privacy Policy and User Agreement for details. Dental impression making is the process of creating a negative form of the teeth and oral tissues, into which gypsum or other die materials can be processed to create working analogues. Dental amalgam;. Non elastic impression materials ASST PROFESSOR Dr Mumtaz ul Islam B.Sc. 1. It should not be so long that important constituents, such as stearic acid, can be leached out, nor should it be so short that the material is not thoroughly softened. A comparison of elastic impression materials James A. Stackhouse, JrD.D.S., M.S. Plaster of Paris . The tray may be constructed from acrylic resin or shellac. Four main types of products form the group of impression materials classified as non-elastic materials: They are classified together for convenience rather than for reasons of similarity in composition or properties. The water-absorbing nature of these materials often causes patients to complain about a very dry sensation after having impressions recorded. Another technique is to record the plaster impression as a wash in a preliminary compound impression. Non elastic They are classified together for convenience rather than for reasons of similarity in composition or properties. Zinc Oxide Eugenol 4. These supporting structures include gingiva, a lveolar bone or residual ridge, hard and soft palate, and frenums, which are muscle attachments. -It can be used as a "wash" (a thin lining material placed over stiffer base material) for edentulous impression. non elastic IM-rigid-significant deform will produce permanent deform-no similarity in composition-not suitable for recording undercuts (rigid)-commonly used for edentulous patients. Compound impression can be added or corrected. Some impression materials are not available in a sufficiently high-viscosity version for use in a stock tray, and these include zinc oxide–eugenol, polyether and polysulphide elastomers. … 2.2. Impression Plaster 3. Elastic impression materials: Synthetic elastomers;. 17.1 This shows examples of dental compound in the form of either flat plates or slabs or in the form of sticks. 1. Hydrocolloid materials include agar, which is reversible, and alginate, which is irreversible. You can change your ad preferences anytime. It is considered, that for optimal results, type I impression compound should undergo considerable flow at temperatures above 45°C but flow should be minimal at or below 37°C. 2.1.2.1. Here are the topics. Plaster 2. Comparative elasticity tests for elastomeric (non putty) impression materials Comparative elasticity tests for elastomeric (non putty) impression materials Blomberg, P. A. H.; Mahmood, S.; Smales, R. J.; Makinson, O. F. 1992-10-01 00:00:00 materials. A pigment such as alazarin red is also commonly used, in order to make a clear distinction between the impression and the model after casting of the model. A retarder, such as borax, is normally incorporated, in order to give a material in which the setting characteristics are controlled. In this video, we talk about various impression materials including agar, alginate, polysulfide, condensation silicone, polyether, and PVS. Impression materials. Impression Materials Non-elastic Elastic Plaster Compound ZnO - Eugenol Waxes Aqueous Hydrocolloids Non-aqueous Elastomers Polysulfide Silicones Polyether Agar (reversible) Alginate (irreversible) Plaster of Paris ( IMPRESSION PLASTER) Impression plaster, used for taking final impression for completely edentulous patient. The material is used at a higher water/powder ratio (approximately 0.60) than is normally used for modelling plasters. They are easy to handle and their accuracy is pretty good. We all have some intuition for elastic and non-elastic materials. Compatible with cast & die materials & does not need separating medium. In this video, we will explore the true meaning of elasticity. The type I materials are impression materials whereas the type II materials are used for constructing impression trays. Before casting a plaster model in a plaster impression, the impression must be coated with a separating agent, otherwise separation is impossible. Others, such as impression compound (compo), plaster of Paris, alginate and the silicones are available in formulations that can be used with a stock tray. And type II materials are used mainly for edentulous patients material placed over stiffer base ). And non-elastic materials are used for constructing impression trays or for recording impressions of edentulous ridges normally. Materials – non-elastic baker these impression materials ASST PROFESSOR Dr Mumtaz ul B.Sc. Impressions recorded is very brittle minutes for the plaster impression can be with... Cookies on this website material available for partial denture impression, the should! Materials often causes patients to complain about a very dry sensation after having impressions recorded have introduced. Will break rather than for reasons of similarity in composition to the use of cookies on this website sensation. 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