system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is brushing your teeth so important for their (our) health? Did our ancestors make any moves towards cleaning their teeth? Is it related to dietary trends over the years?

I feel that before the modern era of tooth care, brushing would have been ridiculed, rudimentary and unsanitary.    How did the hygienic custom begin?
gpt
IANAD(entist), but our modern dental predicament is due to the ridiculous amounts of sugars that we consume in our foods.

While there were toothbrushes and other dental instruments going back hundreds of years, food stuffs had far less sugar; people didn't have over processed industrial starchy-corn-syrup-fructose overloads to contend with.  

A lot of mummies exhumed from around the world have excellent teeth.

Who knows, maybe in another hundred years or so our teeth will have evolved to cope with the influx of sugar.