Impression Material Basics John O. Burgess, DDS, MS. Elastomeric impression materials are used in a variety of dental procedures, and improved delivery systems and materials with better properties have made the impression technique more predictable (Figure 1). This classification is based on the capability of the material to withdraw over the undercuts it has set. Elastic impression materials. It is made from seaweed and is made with components like Sodium alginate, Calcium sulfate and other ingredients which act as retarders. The higher values obtained for Poisson's ratio at this slow … These are used for recording the patient's mouth where undercuts are present. In prosthodontics, impression materials are used to record intraoral structures for the fabrication of definitive restorations. Purpose: To compare the mechanical properties of alginate impression materials mixed with a mechanical mixer (Alginator II, Cadco) and hand mixing. The creep compliance measurements showed that the polysulphide materials were the most viscoelastic followed by silicone and polyether impression materials. CHEMISTRY. Usually used for partial dentures, over dentures, implants and crown and bridge work .The elastic impression materials are: Hydrocolloids Elastomers The tensile properties of 17 hydrophilic impression materials with different consistencies were compared. The value is provided with two numbers: one represents the hardness at 90 seconds after removal from the mouth; the other at 2 hours. Impression materials, that is, the materials used to get an idea about the shape of teeth and the alveolar ridges, can be categorized as nonelastic and elastic materials. Impression Plaster 3. The physical properties of compressive strength, tear strength, stress-strain properties, per cent set, crushing time, impression qualities, and gelation temperature were measured. Ease of Handling:Along with this they have excellent dimensional stability due to 99% of elastic recovery. CHEMISTRY. The polyether was the most nearly ideal elastic material but it had a flexibility comparable to heavy body polysulphide. The mechanical mixer improved elastic recovery and compressive strength of the alginate impression materials tested and had no effect on strain in compression and tear energy. impression materials available in Greece. Impression compound 2. Hence, quadrafunctional hydrophilic impression materials are a combination of properties of polyether impression materials and addition-cured silicone impression materials. While measuring the water, you got involved in a conversation and did not notice how warm it was. These materials can be stretched and bent to a fairly large degree without suffering any deformation. Cresson3 suggested the revision of the testing procedure for compressive strengths of dental elastic impression materials that would apply the load at the rate of 18,000 Gm. Materials and Methods Tensile strength at break (TSb), yield strength (YS), ulti- 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. Four classes of elastomeric impression materials (polysulfide, polyether, silicone, and agar-agar) were evaluated on the basis of linear dimensional stability as a function of time between taking and pouring an impression of mounted teeth. [Elastic reserve properties of impression materials] Coronavirus: ... [Elastic reserve properties of impression materials] Wirz J, Schmidli F. Die Quintessenz, 01 Aug 1987, 38(8): 1383-1390 Language: ger PMID: 3483982 . duplicating materials and consists mainly of an initial comparison of the properties of duplicating materials with agar impression compounds. The creep compliance curves, recovery, and percent set were calculated. During deformation the materials demon-strated linear viscoelastic behavior. The setting time is influenced by temperature, relative humidity, as well as the ratio of accelerator to liquid polymer.2 Since the elastic properties of these materials at the time of removal of the impression from the mouth determine the degree of reproducibility, it was decided to study the elastic properties during the setting period. Although new elastomeric impression materials have been introduced into the market, there are still insufficient data about their mechanical features. Dr. Jones requested that you mix alginate and take an impression. e tested null hypothesis was the fact that there would be no signi cant di erences in mechanical properties among these impression materials. per minute. 2. 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. After the preparation, they are placed inside impression trays. Materials and Methods. Materials and Methods A mechanical mixer facilitates the mixing of alginate impression materials and improves some mechanical properties. Impression materials that have mechanical properties permitting considerable elastic deformation but that return to their original form are classified as: Elastomeric. Impression Agar Poly compound Alginate silicones. [Elastic properties of impression materials and their dependence on testing conditions] Franz T. Dtsch Zahnarztl Z, 27(7):604-609, 01 Jul 1972 Cited by: 0 articles | PMID: 4504807. Elastic impression materials Non-elastic or Rigid Rubbers impression materials Hydrocolloid Polysulfide. ... Properties of Addition Silicones. The creep compliance curves, recovery, and per-cent set were calculated. Ideal Requirements of Impression Materials 1. Tolley LG, Craig RG. During deformation the materials demonstrated linear viscoelastic behavior. Impression materials are used to obtain an accurate replica of hard and soft oral tissues. of various impression materials, but with a specific test undercut, PVS impression materials have the best elastic recovery at over 99% elastic recovery (Donovan, T.E., & Chee, W.W.L. Zinc Oxide Eugenol 4. 12 vinylpolysiloxane, 2 polyether, and 3 hybrid vinylpolyether silicone-based impression materials were … The viscoelastic properties of nine silicone-, polysulfide-, and polyether-based impression materials were determined using creep tests. Fluid enough to adapt to the oral tissues 2. … impression materials. Non-elastic materials are generally not used for taking impressions of crown preparations because of their inability to accurately record undercuts. The accuracy of these final restorations is highly dependent on the impression materials and techniques utilized. I. Inelastic impression material 1. Silicone and polyether derivatives showed their best elastic properties immediately after mixing. Skinner et al.4 and Phillips5 point out the importance of the rate of deformation on the … Impression materials are commonly classified by their elastic properties once set. Plaster and modeling com­ pound are not elastic and do not permit the registration of undercut areas in the mouth. Viscoelastic properties of elastomeric impression materials: polysulphide, silicone and polyether rubbers. .the dental literature as impression materials. Materials with di erent consistencies (heavy-, medium-, and light-body) were investigated. Elastic Impression Materials, Introduction to Elastomers,Silicones Silicones. Purpose. Elastic impression materials. Impression Waxes Impression Plaster. Many impression materials have an elastic recovery of more than 99%. Some years later.in the mid 1920's, agar hydrocolloid impression material was introduced as the first elastic impr~ssion material. Dr Mumtaz ul Islam 11/3/2013 1 2. • • • Resistance of a material to wear Resistance to penetration by an hard object Value of hardness is usually expressed in numbers 11/3/2013 2 3. – However, impression pl aster is still sold. The plaster should be mixed with water or an anti-expansion solution in the ratio of 100g to 50-60ml. Alginate Impression material is an Elastic, Irreversible Impression material which is used to take the impression of both Dentulous and Edentulous Impressions. Measurements are made at the strain rates used in conventional static tests and values reflect this test condition. Creep compliance measurements were shown to be effective in characterizing the elastic, retarded elastic, and viscous properties of polysulphide, silicone, and polyether impression materials. The base and catalyst are either 2 paste substances or a powder and a liquid (which may be water). Group discussion about Properties of Elastic Impression Materials (Synthetic Elastomers) Part 2 Elastic Recovery (%): An impression should return to its original dimensions after removal from undercut areas in the mouth. Elastic materials have a soft consistency but after setting, they become elastic. ZOE Polyether. Non-Elastic Impression Materials. Supplied in 2 pastes or in a gun and cartridge form as light, medium, heavy and very heavy bodied. This test does fulfil a requirement for a simple test to define fully the elastic properties of dental polymeric materials. 2004). 1. method of determining whether the materials possess the elastic properties required to recover adequately after deformation occurring when the materials, used for forming impressions, are removed from the mouth compression set … – It has the same setting reacti on and properties as the gypsum products that are us ed for models and casts. The viscoelastic properties of nine silicone-, polysulfide-, and polyether-based impression materials were determined using creep tests. The ADA recommends elastic recovery greater than 96.5%. These materials are often termed vinyl polysiloxanes. An impression material sustains some deformation as it is removed from the mouth but it must rebound to its pre- removal dimensions. This study deals with measurement of Young's modulus of elasticity and the co-efficient of elasticity of all elastomer im-pression materials in current use in Greece. Plaster – Plaster would seem to be an unlikely impression material. Material and Methods: Three alginate impression materials (Identic, Jeltrate, and Kromopan) were tested. Viscoelastic and Elastic Properties of dental materials dashpot and spring hardness 1. The elastic nature of impression materials prevents the use of most hardness tests except for the Shore A, which uses a Shore A durometer whereby the value describes the material elasticity. An impression with a sufficiently high elastic limit should not sustain permanent deformation. They are easy to handle and their accuracy is pretty good. In addition, the ... Properties of Impression Plaster. The capability of the material to withdraw over the undercuts it has.... Materials available in Greece base and catalyst are either 2 paste substances or powder... 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