11 for Hydrocolloid Impression Material-Agar Type.3 What are the properties of thermoplastic impression compound? separate cast from the impression, use warm water. Polysulfide impression material – Polysulfide impression material was the first non aqueous elastomeric “rubber” impression material developed for dentistry. - Type I compound is referred to as a true impression compound & is used for impressions of edentulous mouths. This compound modification of the impression tray should be firmly adhering to the tray. Other properties: * Non-toxic or irritant * Suitable setting time * Long shelf life * Can be copper plated 2/23/2016 18 Handling and Storage Precautions for Safe Handling: Avoid contact with eyes, skin and clothing.Always wear impervious gloves, chemical safety goggles and protective clothing when handling this material. Compound is trimmed so that 3 to 5 mm of clearance between compound and mucosa exists except in posterior palatal seal area. Plaster, impression compound, zinc-oxide–eugenol, and other materials were originally developed as inelastic impression materials. 1. The properties of duplicating and impression compounds, as influenced by storage for 3 days atelevated temperatures andby 12 boiling andcooling cycles wererecently reported by Duke and Ryge.2 The tests used in this study were those described in the A.D.A. Secondary impression can be made by using low fusing impression compound (green stick) ; green stick compound is kneaded to a homogenous mass and is loaded on the special tray and border movements are implemented. Impression materials are commonly classified by their elastic properties once set. Dimensional change 4. Thermal conductivity 2. Bevan (1963) in a research about properties of impression compound selected 20 representative materials available from British. Rigid impressions (impression compound & zinc oxide eugenol) – Often, polysulfide materials are called “rubber” or “rubber base” materials, even though polyether and silicone materials are also rubber materials. Frederick C. Eichmiller, Carlos A. Muñoz-Viveros, in Contemporary Esthetic Dentistry, 2012. Impression Compounds (All Colors) 02/21/19 Page 3 of 6 Section 7. Non-elastic materials are generally not used for taking impressions of crown preparations because of their inability to accurately record undercuts. Type 1 & Type. Fig 1-Flow change of compound with temperature The compound should be melted under infrared lamp and kneaded in water using a mixing hydrocoloid syring. 6. Early investiga-tions2-7 were largely concerned with desirable compositions of mixtures for impression 1. compound has definite stops against the maxillary tuberosity (ensures teeth do not touch the tray and distort impression). the properties of zinc oxide-eugenol mixtures have been directed to an evaluation of either the dental cements or the impression pastes. Coefficient of thermal expansion 3. Final impression is made either using zinc oxide eugenol or with a medium viscosity elastomer. Low- fusing or Impression compound/ Type I compound - Tray compound is used in the construction of dentures to form a tray that can be employed with other types of impression materials for reproducing the mouth tissues. Brief History Of Clinical Development And Evolution Of The Procedure. Tests were carried out according to ADA standard. Compound impression can be added or corrected. The basic properties of these cements and impression pastes are, to a large extent, reciprocal. Border Molding Complete dentures impressions & check cavity preparations 2. Specification No. Purpose of Impression Compound materials & the different types. 7. As the material is reversible, it can be re-used, but after sterilization. Biological effects 5.