3/2/2024 0 Comments Dental impression rubberThese materials do not require the ability to recover elastically from the large deformations that occur during withdrawal past undercuts on teeth. Consequently, bite impression materials require only sufficient elasticity to withstand separation from the occlusal surfaces of teeth. For example, adequate registrations of the relationship of opposing arches can be removed from the occlusal surfaces of the teeth with minimal deformation. In general, a desirable property of dental impression materials is sufficient elasticity after setting, as discussed more completely below. Handling of these materials in a manner that minimizes viscous deformation after setting will promote their successful use clinically. However, this latter class, which comprises polymeric materials, can demonstrate significant viscous deformation and is more completely described as viscoelastic ( Chapter 1). The two general classes of impression materials for use in orthodontics consist of those materials that can experience only minimal elastic deformation after setting and those that, after setting, can undergo the large elastic deformations required to remove the impression material over the crowns of all teeth. The approach of this chapter is to present some fundamental physical and chemical characteristics of impression materials that are potentially useful to the orthodontist, and then to present the important clinical properties for the ideal impression material with comparisons to available impression materials. Since changes in molecular binding occur during a setting process, changes in properties accompany setting that are important for successful use of the impression material in the clinic and laboratory. ![]() The properties of polymers are dependent upon many factors, but the major factors include the nature of the molecular components and the manner in which these components are bound to one another ( Chapter 1). Materials used to make an impression are usually polymers ( e.g., alginate hydrocolloid and polyvinylsiloxane), although some brittle ceramic materials ( e.g., dental plaster and zinc oxide-eugenol) may also be used for limited applications. The combination of properties before, during, and after setting determines the suitability of the impression material for each clinical situation. This increase in viscosity, referred to as setting, can be due to the physical change of cooling or to a chemical reaction. Most commonly, an impression material is prepared in a low-viscosity state, placed and formed against the oral structures before a significant increase in the viscosity of the material occurs, then removed from the patient’s mouth and used to form the model or to relate models of opposing arches. The purpose of the impression is the formation or establishment in the ensuing “positive” model (typically prepared from a dental gypsum product) of the proper physical dimensions, shapes, and spatial relationships of these structures. Properties After Removal from the Patient’s MouthĪ dental impression material is used to make a mold that has the negative dimensions of the surfaces of a patient’s oral structures. Properties During Removal from the Patient’s Mouth Properties Before Insertion into the Patient’s Mouth Properties of Impression Materials and Relationships to Clinical Use ![]() Hydrorise permits combinations of different viscosities for each specific situation with a range of setting times for any impression procedure.An impression obtained with a polyvinylsiloxane impression material Zhermack Hydrorise Putty Impression material (Normal Set) The synergy of its physical and mechanical properties make Hydrorise a precise and reliable silicone for professionals as they can optimize their working times and also increase the comfort of the patient during impression taking. Hydrorise was also formulated to meet the needs of the patient: thanks to its thixotropy, the silicone does not flow in the mouth during impression taking. Its excellent hydrocompatibilityensures a greater fluidity of the silicone, which adapts perfectly to different dental morphologies and considerably improves the quality of the impression. ![]() The exclusive AMDA (Advanced Moisture Displacement Action) technology, developed by the Zhermack research, favours a precise reproduction of details in the humid environment of the mouth, while preserving the integrity of the impression margins due to its tear strength. High performance for Hydrorise, the hyper-hydrocompatible A-Silicone for high precision impression, which adapts to different impression techniques (double step impression, simultaneous impression with double viscosity and monophase impression) in various clinical situations.
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