Biodegradable toothbrush. Cink kids bamboo toothbrush has a handle made of 100% biodegradable, sustainably grown bamboo. The bamboo is antibacterial and a rot-resistant material so it's very well suited for this purpose. The quality bristles are made of soft, BPA-free nylon 6. The reason we use nylon 6 and not biodegradable fibre is because there is yet no biodegradable fibre that are as effective when it comes to take care of your oral health.