Dimensional Stability and Mechanical Properties of Alginate Hydrocolloid Impression Materials

Objectives: The purpose was to investigate the dimensional stability after prolonged storage (at 100% humidity) and mechanical properties of alginate hydrocolloid impression materials. Methods: Four alginates (JeltratePlus, JP; Alginmax, AL; Hydrogum 5, H5; Kromopan 100, KP) were studied. Eighty dimensional change (DC) specimens were prepared using an ADA detail reproduction die (24.9-mm line), stored in 100% relative humidity, and measured at 5 minutes, and 24, 48 and 120 hours (n=5) using a traveling microscope. Tear energy (TE) specimens were tested according to the Weber and Ryge method. Specimens for flexibility (E at 1 minute) and elastic recovery (K at 45 seconds) were tested on a testing machine (Instron) following ISO 1563. Data were analyzed by analysis of variance and means were compared by Fisher's PLSD intervals at the 0.05 level of significance. Results: Means with standard deviations in parentheses (n=5) are listed. Means with the same superscripted letters within each property were not statistically different.

Conclusions: H5 was dimensionally stable over a 5-day period; JP and AL had shrinkage of 1.45%, and KP expanded. Elastic recovery ranged from 96.2 to 97.6%. Flexibility ranged from 10.8 to 16.9%. Tear energy ranged from 99 from 235 J/m². Supported in part by Dentsply Caulk and Zhermack.