Effect of storage time on the accuracy of casts made from different irreversible hydrocolloids.
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.
Sedda
Maurizio
M
Faculty of Dentistry at the University of Siena in Siena, Italy. maurizio.sedda@gmail.com
Casarotto
Andrea
A
Raustia
Aune
A
Borracchini
Andrea
A
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
D000464:Alginates; D003102:Colloids; D003760:Dental Impression Materials; D003764:Dental Materials; C098917:Hydrogum; D009930:Organic Chemicals; C050135:cavex; C043594:Jeltrate; D002133:Calcium Sulfate