Issues in handling impression materials. 2000

R Giordano

Implant restorations require extreme accuracy since the implants are rigidly fixed. Although impression materials can be highly accurate, small inaccuracies are acceptable because the periodontal ligament allows for tooth movement. This luxury is not available with implants. A problem is the rotation of direct impression copings and distortion of interabutment positions in the master cast. Wee investigated the amount of torque required to displace a coping in eight impression material groups and the positional accuracy of the materials. The initial examination of torque narrowed the acceptable materials to a medium viscosity polyether, a high viscosity addition silicone, and a medium viscosity polysulfide-condensation silicones were eliminated. The results showed that the polyether and addition silicone produced casts with minimal distortion. Finally, it always is prudent to read the manufacturer's recommendations for use of impression materials. Catalyst-to-base ratios vary, as do working and setting times, depending on exact compositions. Impression materials also have various degrees of compatibility with stone, particularly the hydrocolloids, and it is advisable to use the recommended stone. Adhesives should be applied at least 15 minutes prior to loading the impression material. If at all possible, use of a rigid tray is recommended and impressions should be poured in the dental office; this minimizes the error produced at the beginning of the fabrication process. Elimination of errors early in fabrication of a prosthesis help prevent their magnification and result in a better-fitting restoration, requiring minimal adjustment in the end.

UI MeSH Term Description Entries
D010969 Plastics Polymeric materials (usually organic) of large molecular weight which can be shaped by flow. Plastic usually refers to the final product with fillers, plasticizers, pigments, and stabilizers included (versus the resin, the homogeneous polymeric starting material). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed) Plastic
D011145 Polyvinyls POLYMERS derived from the monomer VINYL COMPOUNDS. Polyvinyl
D003102 Colloids Two-phase systems in which one is uniformly dispersed in another as particles small enough so they cannot be filtered or will not settle out. The dispersing or continuous phase or medium envelops the particles of the discontinuous phase. All three states of matter can form colloids among each other. Hydrocolloids,Colloid,Hydrocolloid
D003722 Dental Alloys A mixture of metallic elements or compounds with other metallic or metalloid elements in varying proportions for use in restorative or prosthetic dentistry. Alloy, Dental,Alloys, Dental,Dental Alloy
D003760 Dental Impression Materials Substances used to create an impression, or negative reproduction, of the teeth and dental arches. These materials include dental plasters and cements, metallic oxide pastes, silicone base materials, or elastomeric materials. Dental Impression Material,Impression Material, Dental,Impression Materials, Dental,Material, Dental Impression,Materials, Dental Impression
D003761 Dental Impression Technique Procedure of producing an imprint or negative likeness of the teeth and/or edentulous areas. Impressions are made in plastic material which becomes hardened or set while in contact with the tissue. They are later filled with plaster of Paris or artificial stone to produce a facsimile of the oral structures present. Impressions may be made of a full complement of teeth, of areas where some teeth have been removed, or in a mouth from which all teeth have been extracted. (Illustrated Dictionary of Dentistry, 1982) Dental Impression Technic,Dental Impression Technics,Dental Impression Techniques,Impression Technic, Dental,Impression Technics, Dental,Impression Technique, Dental,Impression Techniques, Dental,Technic, Dental Impression,Technics, Dental Impression,Technique, Dental Impression,Techniques, Dental Impression
D004203 Disinfection Rendering pathogens harmless through the use of heat, antiseptics, antibacterial agents, etc.
D004867 Equipment Design Methods and patterns of fabricating machines and related hardware. Design, Equipment,Device Design,Medical Device Design,Design, Medical Device,Designs, Medical Device,Device Design, Medical,Device Designs, Medical,Medical Device Designs,Design, Device,Designs, Device,Designs, Equipment,Device Designs,Equipment Designs
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D012826 Silicone Elastomers Polymers of silicone that are formed by crosslinking and treatment with amorphous silica to increase strength. They have properties similar to vulcanized natural rubber, in that they stretch under tension, retract rapidly, and fully recover to their original dimensions upon release. They are used in the encapsulation of surgical membranes and implants. Elastomers, Silicone,Rubber Silicone,Silicone Rubber,Elastosil,Microfil,SE-30,Elastosils,Microfils,SE 30,SE30,Silicone Elastomer

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