Paper Title
Gelation Behavior for Polysaccharide/Diatomite Composite Gel and Its Application to Dental Impression Materials

Abstract
Sodium alginate gels cross-linked by calcium ions are widely used for dental material. Since the gelation of sodium alginate is very fast, it has been a problem that the gelation speed is difficult to control. Recently, we proposed a new method to control the gelation speed of sodium alginate gels by ultrasound irradiation. In this study, the effect of ultrasound irradiation on the ion release behaviour from diatomite in pure water was investigated. The diatomite was sintered overnight in a 10 wt% CaCl2 aqueous solution. The solution was filtered and dried to obtain diatomite containing CaCl2 in a dry state. To determine the concentration of ions, the electrical conductivity of the diatomite dispersion was measured by an LCR meter with and without ultrasound irradiation while mechanical stirring. The stirring speed, frequency and applied voltage were 200 rpm, 810 kHz and 0.1 V, respectively. Without ultrasound, the amount of ion release increased with time and remained constant after approximately 30s. With ultrasound, the amount of ion release increased with time and remained constant after approximately 10s. The maximum release rate was calculated to be 9.8 (1/s) without ultrasound and 18 (1/s) with ultrasound.