The part where the bristles are attached to the head can be full of bacteria such as Streptococcus, which causes oral cavity. Antibacterial test for Nano Silver toothbrushes was successfully verified. In the first experiment, a Nano Silver toothbrush was submerged on a culture medium of Streptococcus. The results were positive as bactericidal and antifungal inhibition were not shown. In the second experiment, both Nano Silver toothbrush and ordinary toothbrush were rinsed after brushing. As a result of culturing, the bacterial proliferation was significantly lower in that of the Nano Silver toothbrush than in the ordinary toothbrush. The Nano Silver toothbrush proved its capability in restraining the remaining bacteria. In conclusion,
the Nano Silver toothbrush contains a harmless residual bacterial inhibitory effect rather than bacterial sterilization.