PROBLEM TO BE SOLVED: To provide a medicament excellent in the prevention or treatment of gingivitis.SOLUTION: This invention provides hydantoin derivatives such as 6-fluoro-2,5-dioxaspiro[chroman-4,4-imidazolidine]-2-carboxamide or pharmacologically acceptable salt thereof.COPYRIGHT: (C)2015,JPO&INPIT【課題】歯肉炎の予防又は治療に優れた医薬の提供。【解決手段】6-フルオロ-2,5-ジオキソスピロ[クロマン-4,4-イミダゾリジン]-2-カルボキサミドのようなヒダントイン誘導体又はその薬理学的に許容される塩。【選択図】なし