Fig. Alginate; ii) Elastomeric impression materials Dentist must know the impression materials used for specific condition. Major advances in impression materials and their application have occurred during the last decade, with greater emphasis being placed on rubber impression materials than on dental compound, zinc oxide-eugenol, and agar and alginate. Classification according to elastic properties and chemical type. 16.5b) as well as the viscoelastic properties of the material itself. A dental impression is an imprint of teeth and/or soft tissues, formed with specific types of impression materials that is used in different area of dentistry including Prosthodontics.. A correctly made dental impression will capture a part or all of a person's dentition and surrounding structures of oral cavity. how is an alginate impression disinfected? In addition to the requirements given above, there are two further requirements which apply specifically to materials used for recording undercuts. Requirements for impression material: Accurate & persise - mainly depend on viscosity of the mixed and the ability of the impression material to adapt closely to both the soft and the hard tissues. 16.2 Impression materials. occlusal. A more widely used classification of materials involves consideration of the properties of the set material. Impression Materials A. Classification of impression materials انواع مواد الطبع 1. Impression techniques can be broadly classified into Muco static, Muco compressive, and selective pressure technique. The way in which the material interacts with saliva is another factor affecting fine-detail reproduction. The term elastic as applied to impression materials is fairly unequivocal since the materials which form this group all possess the ability to be stretched or compressed and give a reasonable degree of elastic recovery following strain. As we say, first impression should be good,likewise a dental impression recorded should cover all minute details of the mouth. Additional retention is achieved by using perforated trays. The fine detail recorded in an impression will only be transferred to the gypsum cast if there is adequate ‘wetting’ of the impression surface by the freshly mixed dental stone or plaster. Richard Van Noort. In cases where the impression is made from a hydrophobic material the hydrophilic slurry of calcium sulphate hemihydrate in water may not be able to approach closely enough to the surface of the impression (on a microscopic scale). There are often significant variations between different brands of the same type of material and these variations can spread across the divisions between different levels of viscosity. Once positioned in the patient’s mouth, the materials undergo ‘setting’ by either a chemical or physical process. 1 Azhar Assuit - Asnan 25 Impression :- is a negative reproduction of the tissues Cast :- is a positive reproduction of tissues. Three Impression Material Classifications: A Comparison. The hydrophilic nature of the material allows it to be used in the. Many dental appliances are constructed outside the patient’s mouth on models of the hard and/or soft tissues. Impression plaster; Zinc oxide eugenol; Compound wax; B. Elastic Classification by Use – Materials used to replace lost oral tissues are called r estorative materials. The most widely used and understood method is to classify them according to chemical type. impression compound; ii) Irreversible (thermosest) E.g. The ability of impression materials and gypsum products to reproduce detail in the cast is normally determined by measuring the contact angle which a drop of aqueous calcium sulphate solution makes with the surface of the impression material. Classification of Impression Materials. Impression materials are used to capture accurate hard and soft oral tissues and good impressions can help dentists achieve good clinical outcomes, profitability, and patient comfort. w 1756 Bees wax was the first material to be used for the purpose of impression making. The figures show the different test apparatus, instruments and components. Classification of impression materials. Penguin Ski Club of New Hampshire. 2020/2021 A ____ is a reproduction of someone's bite with the use of wax or elastromeric material. Classification of Impression Materials and Dental Waxes This is a table about the classifications of dental impression materials and dental waxes. Zoe impression paste, Impression plaster. 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