一种抑制牙斑形成的药剂是下列一种或多种药用植物,包括童氏老鹳草Gerani-um thumbergii(地上部分),蓝桉Eucalyp-tus globulus(地上部分),菱Trapnbispinosa果和石榴Punica granatum的果皮、树皮或根皮的酸性有机溶媒提取物。使用的酸性溶媒最好是含0.1％～20％(重量)有机酸(乙酸、丙酸、最好是乳酸)的低级 An agent for inhibiting the formation of plaque is one or more of the following medicinal plants, including Gerani-um thumbergii (above ground part), Eucalyptus globulus (above ground part), Trapnbis pinosa fruit and pomegranate An acidic organic solvent extract of the skin, bark or root bark of Punica granatum. The acidic vehicle used is preferably a low grade containing 0.1% to 20% by weight of an organic acid (acetic acid, propionic acid, preferably lactic acid).