This study investigated the shape of a domestic interdental brush and the size provided by the manufacturer, and prepared basic data for the efficient use of interdental brushes through PHD reclassification of interdental brushes in accordance with international standards. The results of this study used the domestic manufactured interdental brush used in this study did not implement all notation according to international standards, and Japanese notation was implemented with PHD. As the wire diameter and brush diameter of the interdental brush increased, both the manufacturer's presentation PHD and the reclassified PHD increased, and. the PHD reclassified based on international standard standards, only about 47% of the PHD provided by the manufacturer was consistent. The unestablished size standard of interdental brushes hinders the efficient use of interdental brushes, and it is believed that it is essential to find a standardization plan for related size standards.