Dimensional stability of alginate impression material over a four hours time frame

To determine the dimensional stability of alginate impressions poured at varying time intervals in a tropical environment.

Alginate impressions of a master model of truncated metal cones were made and poured at varying time intervals of 5 minutes, 30 minutes, 1 hour, 2 hours and 4hours. The liner dimensional differences between the master cast and stone casts of alginate impressions poured at varying time intervals was determined.

Although, there was observed increasing percentage differences with increasing length of time before pouring of the cast for all the inter-abutment distances measured, there was no statistical significant difference in dimension of the cast at ten minutes for all the distances measured except distance D with mean 50.23 and p value 0.010 while there were statistical significant changes observed at all the other time groups and distances.

Alginate impressions should be cast within 10 minutes although, casts obtained from impressions stored by covering with wet gauze as is commonly done, for not more than 30 minutes will be clinically usable.