The tissues are not displaced during impression taking, hence the material is termed mucostatic. Plaster of Paris is traditionally used as a casting material once the impression has been taken, however its use as an impression material is occasionally useful in edentate patients. Rigid Plaster of Paris (impression plaster) Impression materials can be considered as follows: Inserting a retraction cord into the gingival crevice is one method of retracting gingival tissues away from the tooth. As a result, the gingival tissues must be pushed away from the preparation margin in order for the impression material to be accessible. The preparation border must be accurately captured by the light bodied impression material when taking impressions for crown and bridge work. Impression for provision of fixed prosthesis Functional impression (also known as secondary impression).Two phase two stage: first the putty is set in the mouth then low body weight material is added on the top of ready impression and inserted to the mouth to get the final accurate impression.Two phase one stage: the putty and low body weight impression materials are inserted to the mouth at once.Usually it is the second stage, where the runny impression material is used after an initial impression taken with a more viscous material. "Wash impression" – this is a very thin layer of low viscosity impression material which is used to record fine details.User Guide of Dental Impression material:.Dentures are at rest most of the time, so it could be argued that mucostatic impressions make better dentures, however in reality it is likely that tissue adaption to the presence of either a denture made with a mucostatic or a mucocompressive technique make little difference between the two in the long term.Īnother type of impression technique is selective pressure technique in which stress bearing areas are compressed and stress relief areas are relieved such that both the advantages of muco static and muco compressive techniques are achieved. These impressions will generally lead to a denture that is most stable during function but not at rest. Mucocompressive means that the impression is taken when the mucosa is subject to compression. torus palatinus) and dig into compressible areas. These impressions will generally lead to a denture which has a good fit during rest, but during chewing, the denture will tend to pivot around incompressible areas (e.g. Mucostatic means that the impression is taken with the mucosa in its normal resting position. Impressions can also be described as mucostatic or mucocompressive, being defined both by the impression material used and the type of impression tray used (i.e. zinc oxide and eugenol-based impression paste.silicones ( polyvinyl siloxane): condensation- cured silicones, addition silicones, vinyl polyether silicones (VPES).irreversible hydrocolloids: sodium alginate.Common materials used for dental impressions are: The required type of material for taking an impression and the area that it covers will depend on the clinical indication. oral and maxillofacial surgery for both intra-oral and or extra-oral aims (e.g.maxillofacial prosthetics (prosthetic rehabilitation of intra-oral and extra-oral defects due to trauma, congenital defects, and surgical resection of tumors).Wax mock up of crowns on a cast made from an impression to make impressions of teeth which have been prepared to receive indirect extracoronal restorations such as crowns, bridges, inlays and onlays) prosthodontics (such as making dentures).Impressions, and the study models, are used in several areas of dentistry including: This leaves an imprint of a person's dentition and surrounding structures of the oral cavity.ĭigital impressions using computerized scanning are now available. It then sets to become an elastic solid, which usually takes a few minutes depending upon the material. The impression material is liquid or semi-solid when first mixed and placed in the mouth. It is made by placing an appropriate material in a dental impression tray which is designed to roughly fit over the dental arches. A custom dental model or plaster cast.Ī dental impression is a negative imprint of hard and soft tissues in the mouth from which a positive reproduction, such as a cast or model, can be formed. JSTOR ( March 2018) ( Learn how and when to remove this template message)Īn impression body, made from alginate impression material.Unsourced material may be challenged and removed.įind sources: "Dental impression" – news Please help improve this article by adding citations to reliable sources. ![]() This article needs additional citations for verification.
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