PROBLEM TO BE SOLVED: To provide root canal-filling sealer composition having good wettability to tooth material； less unpleasant odor, irritation, and harmful effects； an excellent biocompatibility； a sufficient allowable operation time suitable for root canal-filling； small dimensional change after curing； and an ability of allowing a cured material to be easily removed during the retreatment of root canal.SOLUTION: According to the present invention, a root canal-filling sealer composition consists of: (a) a polymer of an acid group-containing polymerizable monomer in which part or all of the acidic group forms a salt with an alkali metal； a liquid material containing (b) water and having a pH in the range of 3.5 to 5.5； and a powder material containing (c) an acid-reactive inorganic powder. A cured product obtained by kneading the liquid material and the powder material consists of: (a) 3 to 20% by weight of the polymer of the acid group-containing polymerizable monomer in which part or all of the acidic group forms the salt with the alkali metal； (b) 10 to 60% by weight of water； and (c) 30 to 85% by weight of the acid-reactive inorganic powder.SELECTED DRAWING: None【課題】歯質に対する濡れ性が良く、不快臭や刺激、為害作用が少なく生体親和性に優れ、根管充填に適した充分な操作余裕時間を有し、且つ硬化後の寸法変化が少なく、さらに再根管治療時に硬化物を容易に除去可能である、根管充填用シーラー組成物の提供。【解決手段】（ａ）酸性基の一部又は全部がアルカリ金属と塩を形成している酸性基含有重合性単量体の重合体、及び（ｂ）水を含み、ｐＨが３．５～５．５の範囲にある液材と、（ｃ）酸反応性無機粉末を含む粉材からなる根管充填用シーラー組成物。液材と粉材を練和して得られた硬化物が、（ａ）酸性基の一部又は全部がアルカリ金属と塩を形成している酸性基含有重合性単量体の重合体：３～２０重量％、（ｂ）水：１０～６０重量％、（ｃ）酸反応性無機粉末：３０～８５重量％の範囲である、根管充填用シーラー組成物。【選択図】なし
