To establish an enamel blast cell strain that is suddenly immortalized while maintaining the properties of the primary culture and provide a technique for using a product from the cell culture for the regeneration of the periodontal tissue.

This invention is the technique for producing an enamel matrix having a biological action by using a ameloblast precursor cell obtained from the lower jaw molar teeth of a new born mouse and being success in immortalization. The invention comprises a variety of purified enamel matrix substrates and their derivatives that are produced by ameloblast precursor cells and is used for regenerating periodontal tissues. Further, this invention comprises is a periodontal therapy using ameloblast precursor cells and enamel matrix proteins.