Effect of Hot Water Immersion on Diametral Tensile Strength of Fluoride-releasing Restorative Materials

Abstract

This study examined the effect of hot water immersion on the mechanical properties of fluoride-releasing restorative materials. Three different polyacid modified resin composites (PMRC) [Dyract AP, Reactmer, and Xeno CF] and two different light-cured glass-ionomers [Fuji II LC EM (LC) and Vitremer (VT)] were examined. The specimens were immersed in deionized water at 37℃ for 28-days or were subjected to continuous hot water (90℃) flow for 28-days in the Soxhlet extraction apparatus to accelerate degradation. The diametral tensile strength of each specimen was determined. Thermal degradation by continuous hot water flow for 28-days did not significantly reduce the strength of PMRC or VT. There was a significant decrease in the strength of LC by thermal degradation. The structural integrity of all fluoride-releasing restorative materials was deteriorated due to thermal degradation by a continuous hot water flow over 28-days. However, this structural deterioration did not notably reduce the diametral tensile strength of the materials except for LC.