The effects of environment and time intervals on the dimensional stability of three indigenously produced irreversible hydrocolloids.

ABSTRACT

Aim: 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 and Materials Three alginates were tested Zelgan (Dental Products of India), DMC Algitex (Dental manufacturing & marketing Company) and A1 Alginate (occlusion products of India). A special stainless steel die representing a crown preparation was used to obtain impressions. These impressions were poured at different time intervals i.e immediately after a lapse of 5 minutes, 15 minutes, 30 minutes & 1 hour. Impressions were stored in a three different environments i.e. Air, water & 100% humidity. The casts were made & data were analyzed. Results: The dimensional stability of the alginate impressions was both material & time dependent. Conclusion: The dimensional stability of the alginate impressions is influenced by the selected materials and the storage time. An atmosphere of 100% humidity appears to be best storage medium. Clinical Significance: Alginate impressions should generally be poured immediately . Longer the period of storage more significant dimensional changes were observed.