There have been reported cases of allergic reactions to alginate impression material. In one study, it was shown that alginate impressions could also be used as final impressions for indirect restorations with chamfer finish lines. IndicationsÄȘlginate impression can be used for the fabrication of a primary cast in prosthodontics, study models in orthodontic, and duplication of casts. Alginates remain an economical option and easily manipulated impression material. Agar-agar impression materials are no longer used in clinics because of the inconvenience of manipulation whereas, alginates are still popularly advocated. The alginate powder, when mixed with water, forms a gel, which is known as alginate. Chemical treatment of brown algae led to the formation of a new elastic impression material which had an alginate base which is an irreversible hydrocolloid and was much easier to use. ![]() During the World War II, agar-agar was no longer available. The use of agar-agar was not convenient as it required special equipment such as heaters, syringes, and water-cooled rim lock trays. This substance, which was a jelly-like substance, became soft when heated and hardened when cooled. All of these compounds were reversible hydrocolloids with agar-agar as their fundamental ingredient. Many companies started manufacturing a similar material. In 1925, an Austrian, Alphons Poller, invented and patented a material known as "Nogacoll." After Alphons Poller's death in 1931, the formula was attained by a company and given a new name: "Denticole." The idea evolved from the making impressions of statutes using jelly molds. As a result, researchers invented flexible impression materials which can retain the elastic nature even after a complete set. A material which is sufficiently elastic and that can be retrieved from the mouth without any defect is a solution for this issue. Most of the failures occur as a result of the rigid nature of the impression material used, which results in an inaccurate impression of the oral tissues and undercuts surrounding the teeth. ![]() Making of impressions for partial dentures is more difficult compared to those for complete dentures.
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