J Korean Acad Prosthodont.  2020 Apr;58(2):86-94. 10.4047/jkap.2020.58.2.86.

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

• Bang HJ
• Shim HA
• Cho YE
• Park EJ

• KMID: 2500020
• DOI: http://doi.org/10.4047/jkap.2020.58.2.86

Abstract

Purpose
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-pour alginate. Materials and methods: An arch-shaped metal model was fabricated, and one conventional alginate and two extended-pour alginates were used to take impressions using different mixing methods (hand and automatic). 120 impressions were taken (40 per each alginate) and stone models were made in accordance with the different storage times (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 was no statistically significant difference in the dimensional accuracy between two mixing methods, and the volume change was minimum when the stone was poured immediately in all groups. Dimensional accuracy showed a statistically significant difference between groups after 2 days of storage, and extended-pour alginate showed higher accuracy after 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 for extended pour alginate. Conclusion: The mixing method of alginate does not affect volume stability. Although extended-pour alginate has better volume stability than conventional alginate for a long time, it is recommended to pour stone as soon as possible. (J Korean Acad Prosthodont 2020;58:86-94)

Keyword

Alginate; Dimensional stability; Extended-pour alginate; Mixing method; Storage time