Abstract
The auther have heen studying the electrophoresis of ions in the hard tissue of tooth and some results obtained are shown as follows.
1) Ions were more permeating into the part which is composed of more organics.
2) Enamel and cement were less permeable than dentine. Dentine transparent layer was hard to permit ions.
3) Ions were settled down in E-D junction, C-D junction, enamel surface and the inner layer of dentine.
4) Ions were not settled down in the middle of enamel and cement.
5) When enamel and Thomes' granular layer were taken away from normal teeth, ions were permeable more easily as in the cervical part.
6) It took less than 1/50 second for ions to penetrate from enamel surface into tooth pulp under 60 volt.
