Low-environmental-impact Bamboo Toothbrushes Demonstrate Comparable Hygienic Condition to That of Plastic and Biomass Plastic Toothbrushes after Use and Storage

Brushing with a toothbrush is effective for removing oral biofilms. However, toothbrushes can be a source of infectious diseases after use. Recently, the environmental impacts of plastics, such as marine pollution, have become an issue. This includes the disposal of plastic toothbrushes. Consequently, bamboo toothbrushes, with a low environmental impact, have become widely-used as alternatives. Although there are many reports on the hygiene of plastic toothbrushes after use, there are few reports on bamboo toothbrushes. Thus, we compared the hygiene of bamboo toothbrushes with those of plastic and biomass plastic toothbrushes after use and storage. Three types of toothbrushes were immersed in bacterial cultures and washed, and the number of bacteria on the toothbrushes after 12 and 24 h of storage was examined. The number of bacteria on the bamboo toothbrushes immediately after immersion was significantly higher than on the other two types, but this number was 95–99％ lower after 12–24 h of storage. No differences were observed for different bacterial species（Actinomyces oris and Streptococcus mutans）or different storage conditions（wet and dry）. However, pre-wetting before immersion significantly reduced the number of bacteria on the bamboo toothbrushes. These results indicate that the hygienic conditions of bamboo toothbrushes after 12–24 h of storage were comparable to those of plastic or biomass toothbrushes. Furthermore, pre-wetting the bamboo toothbrushes before use improved hygiene immediately after use. Bamboo toothbrushes are a better choice as they provide equivalent hygiene to that of plastic toothbrushes and also have a low environmental impact.