Elastomeric impression materials used in modern orthopedic dentistry

Abstract

The article presents a review of elastomeric impression materials used in orthopedic dentistry at the present time. As is known, the elastomer group is divided into silicone, polyester, thiocol (polysulfide) materials. Silicone impression materials are characterized by wide application in orthopedic dentistry. The structural basis of silicone materials is polymethylsiloxane with active terminal hydroxyl groups. Polyester impression materials are complexes consisting of two pastes the main and the catalyst. The main paste contains low-molecular-weight polyester with terminal ethylenimine groups, as well as fillers such as colloidal silicon oxide and plasticizers. The catalyst paste contains aromatic ether of sulfonic acid. When these two pastes are mixed, ionic (cationic) polymerization will occur, starting with the formation of a primary alkyl radical, then the ethylenimine ring opens, followed by the growth of macromolecular chains and their crosslinking. Polysulfide are available in the form of two pastes, the main and the catalyst, of different colors, which are mixed immediately before performing the work. The main paste contains polysulfide or mercaptan rubber, and the catalyst paste contains an oxidizer. It should be noted that lead oxide is most often used as an oxidizer. The resulting polymer does not have a stereoregular structure, which causes its stickiness. It is technologically very difficult to obtain a polymer with a stereoregular structure. Having carried out a theoretical comparison of the listed types of elastomeric impression materials according to their properties, chemical composition, advantages and disadvantages, it is possible to distinguish polyester and polysulfide impression materials as more advanced, and silicone have a large number of disadvantages, but are often used in dentistry due to the presence of domestic representatives and relatively low cost.