buzzfeed The Romans used to clean and whiten their teeth with urine. Apparently it works.
Is this true?
According to wikipedia and the sources cited there, yes they did. And yes it worked. Urine contains urea, which decomposes into ammonia, which is a modern day cleaner, and is even used in lots of toothpaste.
Here's a video about it. Romans used urine to clean and whiten their teeth, they collected urine, and used it for many other purposes. They even enacted taxes on it.