Abstract： Objective To evaluate and compare the physical and chemical properties of four different dental cements under long-term water storage.Methods A glass-ionomer cement (A:Fuji Ⅰ),a resin reinforced glass-ionomer (B:Fuji Plus),a self-adhesive resin cement (C:G-Cem),and an etch & rinse resin cement (D:Duolink) were taken as samples.According to ISO 4049,water sorption and solubility of four resin cements under different storage times (1 week,1,3,6 and 12 months) were calculated (n=5),meanwhile their surface Knoop micro hardness values were measured.Results Surface cracks were detected on sample B and C after 12 months.Sample A was fragmentized after 6 months.Sample B showed significantly lower surface hardness after 12 months than it did after the first 24 hours of water storage (P＜ 0.05).Sample D showed significantly lower water sorption than other cements did at all exam time point.The highest water sorption values were observed in Sample D after 1 month [(40.8±2.5) μg/mm3],in Sample B after 3 months [(551.3±22.5) μg/mm3],in Sample C after 12 months [(147.5±8.3) μg/mm3].The highest solubility values were detected in Sample B after 3 months [(105.3± 10.5) μg/mm3],in Sample C after 12 months [(79.3±6.2) μg/mm3],and in Sample D after 12 months [(23.9 ± 6.9) μg/mm3].Conclusions Among the four types of cements,the etch & rinse resin cement showed the best stability of physical and chemical properties under long-term water storage.