The effect of pouring time on the dimensional stability of casts made from conventional and extended-pour irreversible hydrocolloids by 3D modelling

摘要

Background/purpose The aim of this study was to determine the accuracy of casts made from irreversible hydrocolloid impressions with immediate and delayed pouring. Materials and methods A master model was mounted on a modified articulator designed to standardize impression procedures. A total of 250 impressions were taken and grouped into 25 groups ( n ?=?10) according to irreversible hydrocolloid material (CA37, Tropicalgin, ColorChange, Hydrogum 5, and Hydrocolor 5) and storage time (0 hours, 1 hour, 24 hours, 72 hours, and 120 hours). Impressions were stored at 23?±?1°C and 100% relative humidity and poured with gypsum at the predetermined storage time. Casts were scanned with a three-dimensional (3D) model scanner. The digital models were measured and subtracted from the measurements obtained from the master model. The absolute values of dimensional differences were statistically analyzed using two-way analysis of variance (ANOVA) and post hoc Fisher LSD test (P??0.05). Results Different irreversible hydrocolloids and pouring times showed significant differences (P??0.001). In all irreversible hydrocolloids, no statistically significant differences were found with impressions poured after 0 hours, 1 hour, and 24 hours of storage (P??0.05). However, after 72 hours and 120 hours of storage, Tropicalgin and CA37 irreversible hydrocolloid impressions were found to be significantly different (P??0.05). Moreover, ColorChange, Hydrogum 5, and Hydrocolor 5 irreversible hydrocolloid impressions were not statistically different up to 120 hours (P??0.05). Conclusion All of the conventional and extended-pour impression materials tested in this study can be poured up to 24 hours with accuracy, if impressions are correctly stored. Extended-pour impression materials (ColorChange, Hydrogum 5, and Hydrocolor 5) can be poured up to 120 hours, if stored correctly.