Evaluation Of Sedimentation Tendency For Low Viscosity Luting Materials

Objectives: Comparison of mainly identical formulations with different amount of fused silica as a thickener adjusted by the same consistency and measuring them with a MLS instrument. Transmission for non-opaque samples and backscattering for opaque samples are detected by two detectors.
Methods: Four formulations were applied, were Base1 and Base2 differentiate by 3.25% fused silica and Catalyst1 and Catalyst2 differentiate by 1.1 % fused silica. The samples were stored at different, elevated temperatures (37°C, 50°C and 70°C) for accelerated sedimentation testing.
A Turbiscan Lab (MLS) instrument was used with TurbiSoft 2.1.0.52 as an analysis and measurement software. Turbiscan Stability Index (TSI) was measured for five weeks.
Statistical analysis were done using a general linear mode (ANOVA) and Tukey’s range test to determine statistical differences (p<0.05) if applicable.
Results: After 5 weeks stored at 37°C the differentiation was low or not detectable, at 50°C and 70°C the sedimentation could be quantified in a significant amount.
Conclusions: Within the limitation of this method, the sedimentation of different formulations could be measured and quantified with a MLS instrument. A higher amount of fussed silica by the same consistency improved significantly the sedimentation resistance especially at higher temperatures of 50°C and 70°C.