Water sorption of three types of composite resins

Silorane low shrink composite resin material introduced with a non-methacrylateresin matrix to realize a fundamental improvement in cure shrinkage, clinical andphysical properties. The aim of this study is to measure the water sorption of threetype of composite material: Filtek P90, Filtek P60, IPS Empress composites afterimmersion in deionized distilled water as a function of time.Thirty disk shape plastic molds (4 mm diameter and 2mm thickness) wereconstructed to form composite blocks. Teen blocks were made from Filtek P 90(Silorane) GI, Filtek P 60 (packable) GII and IPS Empress (Nanohybrid) GIII. Allspecimens were placed in a silica-gel desiccator for 48 hours. The samples were thenweighed three times using calibrated electronic microbalance and the average readingwas recorded to the nearest 0. 0001g then specimens were kept in individualcontainers in deionized distilled water at 37 oC. All specimens were periodicallyweighed. The weight measurements were taken from the second day after incubationand continue as one measurement every week for 6 weeks. Data were subjected tostatistical analysis using descriptive analysis, ANOVA and least significantdifferences LSD test.Statistical analysis of the results showed that all the specimens continued to gainweight for a period of 4 weeks. After that period the weight gain continued, althoughat reduced rate. Filtek P90 (Silorane) GI has highly significant less water sorptionvalue ( p < 0.01) than the other groups after 6 weeks, while there was no significantdifferences ( p > 0.٠٥) between IPS Empress (Nanohybrid ) GIII and Filtek P60 (Packable ) GII in their water sorption value with higher value for GIII.Silorane which based on siloxane and oxirane resin matrix has less value after 6weeks followed by Packable composite while IPS Empress has higher value for watersorption. This study concluded that the differences in water sorption capacity of thethree composite resin materials are related to the differences in the type of resinmatrix, the amount of filler loading and filler particle size.