Even though the spice trade between the Middle East and India dates back more than 4,000 years, sugar didn’t make it into the mix of traded goods until much later. People knew about sugarcane; the prophet Jeremiah wrote of “sweet cane from a distant land.” But it just didn’t make it to Europe from Asia until the 1100s. When it hit, it came in slowly and was hugely expensive, but it was instantly popular with people who could afford it, and became a way people could show off their wealth (other than the usual palaces and fancy clothes).
People figured out pretty quickly that a lot of sugar rotted your teeth. However, because only the rich could afford sugar, it became a status symbol. In the 1500s, as sugar began to trickle into England from the newly discovered and planted islands in the Caribbean, the teeth of more and more wealthy people were endangered.
However, because people knew you had to be rich to have rotting teeth, people who couldn’t afford sugar actually started cosmetically blackening their teeth, so they would look wealthy.
Kind of a contrast to today, where wealth means having perfect teeth, even if they’re not the ones you were born with.