EFFECT OF LIGNOCELLULOSIC FILLER ON MECHANICAL AND RHEOLOGICAL PROPERITES OF ALGINATE-BASED DENTAL IMPRESSION MATERIALS

Dental alginate impression materials have some disadvantages, such as poor dimensional stability due to syneresis and imbibition, fast setting time in a hot environment, low tensile resistance and poor rheological properties. In this study, lignocellulosic material was incorporated as a filler into commercially available alginate impression material. The powder was mixed in different ratios (2%, 4%, and 6%) to prepare different experimental materials (E1, E2, and E3, respectively). The samples were tested to evaluate their dimensional stability, setting time, tensile strength and rheological properties. The dimensional stability significantly increased by the addition of lignocellulosic powder (2%, 4%) to alginate, as compared to control groups. However, the addition of 6% lignocellulosic powder decreased the dimensional stability, as compared to the control. Also, the mean values of setting time, tensile strength and viscoelasticity were the highest in E3 series, followed by E2 and the least in the control groups. The mean value of the flow and drip properties was reduced statistically by adding increasing concentrations of lignocellulosic powder to alginate. Thus, the addition of lignocellulosic powder to alginate impression material improved the dimensional stability, tensile strength, setting time, viscoelasticity, but reduced the flow properties.