Here are some fun facts about teeth:

1. Tooth enamel is the hardest substance in the human body.
2. The average person spends 38.5 days brushing their teeth over the course of their lifetime.
3. Teeth are unique, just like fingerprints. No two people have the exact same set of teeth.
4. The first toothbrushes were made from animal hair and bamboo, and were used in China over 1,000 years ago.
5. The blue whale has the largest teeth of any animal, with some teeth measuring up to 1 foot in length.
6. Humans have two sets of teeth in their lifetime: a set of baby teeth, and a set of permanent teeth.
7. Teeth are as unique as our fingerprints. No two people have the same set of teeth.
8. Teeth contain stem cells, which means that they can be used to regenerate other body tissues.
9. Tooth decay is the most common chronic childhood disease in the United States.
10. Sharks can grow and replace thousands of teeth over the course of their lifetime.