Dr. Drew Sutton M, board certified otolaryngologist conducted an experiment with a pair of 2,500-year-old teeth from one of an ancestors(Real once-alive teeth).

And noted that despite being buried deep in the mud for centuries...

Not even a small cavity or crack, even though toothpaste, brushes or dentists were inexistent back then.

So, how come teeth can thrive for thousands of years outside of the mouth, covered in dirt and worms, while in the mouth they get ruined by plain chocolate?