Mechanical Properties of Alginate Impression Material Modified with Silica Fume

Objective: To investigate the feasibility of utilizing silica fume by-product in improving the mechanical properties of an experimentally prepared dental alginate impression material.

Method: Locally prepared silica fume byproduct was obtained from the Egyptian Ferroalloys Company (EFA CO.) located in Edfu city, Aswan-Egypt. Silica fume was added to the experimentally prepared dental alginate impression material in three different concentrations (5, 10 and 15%) on the expense of the diatomaceous earth filler. The experimental mixtures were then evaluated according to the ANSI/ADA specification no.18 for dental alginate impression material regarding: strain in compression, compressive strength and recovery from deformation. Data were statistically analyzed using One-way Analysis of Variance (ANOVA) (P value ≤ 0.05).

Result: Experimental alginate mixture containing 15% Silica fume showed the highest statistically significant mean strain in compression and compressive strength (14.5% and 0.79 MPa respectively). No statistically significant difference between the experimental alginates containing 5% and 10% Silica fume; both showed lower mean strain in compression (12.9% for both) and compressive strength (0.70 and 0.73MPa respectively) values. Unmodified experimental alginate mixture showed the statistically significantly lowest mean strain in compression (11.7%) and compressive strength (0.49 MPa) values. Regarding the recovery from deformation, no statistically significant difference between the unmodified experimental alginate mixture, and the experimental alginate mixtures containing 5%, 10% and 15% Silica fume.

Conclusion: The addition of the Silica fume by-product to the experimentally prepared alginate mixtures did improve its mechanical properties regarding; strain in compression, compressive strength and recovery from deformation.