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 Silver Nano toothbrushes was successfully verified. In the first experiment, a Silver Nano 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 toothbrush and ordinary toothbrush were rinsed after brushing. As a result of culturing, the bacterial proliferation was significantly lower in that of the Nano toothbrush than in the ordinary toothbrush. The Silver Nano toothbrush proved its capability in restraining the remaining bacteria. In conclusion,
the Silver Nano toothbrush contains a harmless residual bacterial inhibitory effect rather than bacterial sterilization.