The objective of this study was to compare the effect of calcium silicate based-material and glass ionomer
cement on root dentin demineralization resistance. Sixty root dentin specimens from human permanent premolars
were prepared to obtain standardized cavities and randomly divided into 4 groups (n=15): group1-negative control
(no restoration), group 2- conventional glass ionomer cement, group 3-resin modified glass ionomer cement and
group 4- calcium silicate based-materials. The surface knoop microhardness test was performed on root dentin at
50, 100, 150 and 200 μm from restoration margin. The specimens were subjects to pH-cycling model then, surface
knoop microhardness test was measured again. Two specimens from each group were randomly selected to assess
mineral composition in dentin adjacent to restorative materials using energy dispersive X-ray spectroscopy. Data
were analyzed using two-way repeated measures ANOVA, one-way ANOVA and Tukey HSD test, repeated measures
ANOVA and Bonferroni post-hoc test with the level of significance at p<0.05. Surface microhardness loss of root
dentin from group 4 was significantly lower than the other groups in every distance from restoration margin. Surface
microhardness loss of root dentin from group 2 and 3 was not significantly different but the surface microhardness
loss from both groups was significantly different from group 1. From the results of this study, root dentin restored
with calcium silicate based-material had higher demineralization resistance than root dentin restored with glass
ionomer cement until 200 μm from restoration margin.