Reliability of repour of varying thickness alginate impression following extended storage time intervals

Background: Obtaining multiple casts from an impression is desirable for the completion of numerous procedures for a patient. Recent literature on newly introduced extended-pour alginates reveals promising results for delayed pouring. However, literature on multiple pouring of impressions and the effects of impression thickness and storage time is not available. Subjects and Methods: Conventional and extended-pour alginates of various thicknesses (2, 4, and 6 mm) were evaluated for linear dimensional changes in both the intra-abutment and inter-abutment distances. Casts were poured twice with the time difference between the pours being 45 min; the storage time, however, was varied (15 min, 1 h, and 1, 3, and 7 days). The intra-abutment and inter-abutment measurements were compared with those of the standard metal die. Results: Compared with that of the metal die, the casts poured with 6 mm thickness of the impression material showed better accuracy between the first and the second pours and also revealed smaller statistical differences. Further, Cavex performed better than Major and GC brands. Conclusions: The dimensional stability of different alginate materials vary with thickness, storage time, and multiple pouring in both conventional and extended-pour alginates. Shorter storage time and greater thickness of the impression material are preferred when the same impression has to be poured twice. Clinical Significance: Alginate impressions can be poured twice, if made in adequate thickness and stored for short storage time, to generate additional set of accurate casts that aid in documentation, diagnostic and treatment procedures.