Effect of High-Molecular-Weight Sodium Alginate on the Viscosity and Characteristics of Alginate Impression Materials

Purpose: In this study, we investigated the effects of addition of high-molecular-weight sodium alginate to alginate impression materials with the aim of developing a new high-viscosity impression material.Methods: Four experimental alginate impression materials were prepared based on a conventional material (control material) by varying the percentage of addition of high-molecular-weight sodium alginate in the range of 50% to 100%. The viscosity after mixing, setting time, recovery from deformation, strain in compression, compressive strength, and compatibility with dental stones was determined in accordance with the ISO 1563 and ANSI/ADA Specification no. 18. Results were analyzed using ANOVA and linear regression.Results: All the experimental materials exhibited significantly higher viscosity than the control material (P<0.05). A significant and positive relationship was observed between the addition rate and the viscosity (P<0.05). In the specification tests, all the experimental materials were found to be within specification limits, and not significantly different from the corresponding values of the control material.Conclusion: The addition of high-molecular-weight sodium alginate to an alginate impression material can be effective for increasing the viscosity of the material without deterioration of the properties of the material.