Abstract: Objective: To observe the apical sealing ability of β-Ca₂SiO₃/CSH composite materials. Methods: Sixty-six premolars with the sigle root canal were used in this study. The teeth were randomly divided into six test groups,10 in each group. A was C_1.4Si, B was C_1.4Si/CSH₁₀, C was C_1.4Si/CSH₃₀, D was C_2.0Si, E was C_2.0Si/CSH₁₀, F was C_2.0Si/CSH₃₀. In addition,there were positive and negative control groups, 3 in each group. Protaper was used to prepare the root canal and the composite was filled into the root canal. The method of the dye penetration was performed to evaluate the apical sealing ability. Results: There were significant differences of the apical sealing ability between A and C or D and F(P<0.05). Conclusion: The more CSH of β-Ca₂SiO₃/CSH complex was, the larger value of the apical microleakage was.

Key words: β-Ca₂SiO₃, α-gypsum microleakage