Effect of mixing method and storage time on dimensional stability of alginate impressions materials / 대한치과보철학회지

ABSTRACT

The purpose of this study is to compare the volume stability depending on the mixing methods and storage time for the conventional alginate and extended-pouralginate. Materials and methods: An arch-shaped metal model was fabricated, and one conventional alginate and two extended-pour alginates were used to take impressionsusing different mixing methods (hand and automatic). 120 impressions were taken (40 per each alginate) and stone models were made in accordance with the different storagetimes (immediate, 2 days, 5 days, and 6 days). The models were scanned with a 3D table scanner and dimensional change was measured by superimposing the scan data.Using SAS 9.4 (SAS Institute Inc., Cary, NC, USA), the general linear model and Tukey’s post hoc test was conducted for statistical analysis (P<.001). Results: There wasno statistically significant difference in the dimensional accuracy between two mixing methods, and the volume change was minimum when the stone was poured immediatelyin all groups. Dimensional accuracy showed a statistically significant difference between groups after 2 days of storage, and extended-pour alginate showed higher accuracyafter 5 days of storage comparing to conventional one. Large amounts of volume change were showed at 2 - 5 days for conventional alginate and at 5 - 6 days forextended pour alginate. Conclusion: The mixing method of alginate does not affect volume stability. Although extended-pour alginate has better volume stability than conventionalalginate for a long time, it is recommended to pour stone as soon as possible. (J Korean Acad Prosthodont 2020;5886-94)