We know what the dentist says: Floss your teeth every day. But did you know typical dental floss is not natural? It's a mixture of nylon string covered with a petroleum-based coating. It's not only non-recyclable, it's also non-biodegradable. Never flush dental floss down the toilet; it can clog pipes and cause problems at water treatment plants. But don't skip flossing because you think it's a greener thing to do. Instead, look for biodegradable dental floss made from materials like silk coated with rice bran and natural waxes. It'll do the job and can be safely disposed of.