Effect of storage time on mechanical properties of extended-pour irreversible hydrocolloid impression materials

Statement of problem: Recent commercial extended-pour irreversible hydrocolloid impression materials (EPIHIMs) claim to maintain dimensional stability up to 120 hours. However, data regarding their mechanical properties and performance after 120 hours of storage are lacking. Purpose: The purpose of this in vitro study was to test the elastic recovery, strain in compression, and tear strength properties of 5 commercially available EPIHIMs, immediately after preparation and after 120 hours of storage under specific storage conditions. Material and methods: A total of 150 specimens were prepared in accordance with the ISO 21563:2013 standard from 5 commercially available EPIHIMs (Blueprint Xcreme, Kromopan, Alginmax, Hydrogum 5, and Alginelle). The specimens were subjected to elastic recovery, strain in compression, and tear strength tests immediately after specimen preparation (n=5) and after 120 hours of storage inside clear plastic zipper bags held at 23 °C (n=5). Data were analyzed with a multivariate analysis of variance (MANOVA) test for brand and duration parameters. Normality of data was analyzed with the Shapiro-Wilk test. The Duncan test or Games-Howell test was used for multiple comparisons (?=.05). Results: Elastic recovery and strain in compression values of the EPIHIMs tested were affected by brand and duration parameters (P.05). Data distribution was normal except for Alginmax in terms of the elastic recovery values and Blueprint Xcreme in terms of the strain in compression values (P.05). However, 120 hours of storage led both to a statistically significant decrease in mean strain in compression values of the tested EPIHIMs (P.05) and a statistically significant difference among mean strain in compression values of the tested EPIHIM brands (P.05). However, statistically significant differences were present among mean tear strength values of the tested EPIHIM brands tested immediately after preparation (P<.001) and after 120 hours of storage (P<.001). Conclusions: Despite variations in elastic recovery, strain in compression, and tear strength properties of the EPIHIMs tested, all the materials fulfilled the requirements to comply with the ISO 21563:2013 standard even after 120 hours of storage. © 2019 Editorial Council for the Journal of Prosthetic DentistryTürkiye Bilimsel ve Teknolojik Araştirma Kurumu Türkiye Bilimsel ve Teknolojik Araştirma Kurumu: 215M056This study was financially supported by T?rkiye Bilimsel ve Teknolojik Ara?t?rma Kurumu (The Scientific and Technological Research Council of Turkey) with the project #215M056