title: Effect of storage time on the accuracy of casts made from different irreversible hydrocolloids.
abstract: OBJECTIVE
  Several new irreversible hydrocolloid formulations have recently become available with claims of an improved dimensional stability by the manufacturers. The aim of this study was to evaluate the accuracy of casts made from alginate impression materials poured immediately and after specific storage periods.
  
  
  METHODS
  Five alginates were tested: CA 37 (Cavex); Jeltrate (Dentsply Caulk); Jeltrate Plus (Dentsply Latin America); Hydrogum 5 (Zhermack); and Alginoplast (Heraeus Kulzer). A master model was mounted on a special device and used to obtain the impressions. These impressions were stored at 23 degrees C and 100% relative humidity, then poured with gypsum immediately, and again after 24, 72 and 120 hours. The casts were measured and the data were analyzed by one way analysis of variance (ANOVA) and Tukey test at p<0.05.
  
  
  RESULTS
  The dimensional stability of the alginate impressions was both material and time dependent (p<0.05). After 24 hours of storage, only Alginoplast and Hydrogum 5 comply with the master model (p>0.05). After 72 and 120 hours, only Hydrogum 5 was dimensionally stable (p>0.05).
  
  
  CONCLUSIONS
  The dimensional stability of the alginate impressions is influenced by the selected material and the storage time.
  
  
  CONCLUSIONS
  Alginate impressions should generally be poured immediately. However, some new types of alginate may have the pouring delayed.
authors.affiliation: Faculty of Dentistry at the University of Siena in Siena, Italy. maurizio.sedda@gmail.com
authors.forename: Maurizio
authors.initials: M
authors.lastname: Sedda
authors.forename: Andrea
authors.initials: A
authors.lastname: Casarotto
authors.forename: Aune
authors.initials: A
authors.lastname: Raustia
authors.forename: Andrea
authors.initials: A
authors.lastname: Borracchini
mesh_terms: D000464:Alginates / Q000737:chemistry*; D002133:Calcium Sulfate / Q000737:chemistry; D003102:Colloids / Q000737:chemistry*; D003760:Dental Impression Materials / Q000737:chemistry*; D003761:Dental Impression Technique; D003764:Dental Materials / Q000737:chemistry; D006801:Humans; D006813:Humidity; D008422:Materials Testing; D003765:Models, Dental; D009930:Organic Chemicals; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
chemical_list: D000464:Alginates; D003102:Colloids; D003760:Dental Impression Materials; D003764:Dental Materials; C098917:Hydrogum; D009930:Organic Chemicals; C050135:cavex; C043594:Jeltrate; D002133:Calcium Sulfate