Scumbag teeth

It's the sugar bro! THE SUGAR!!!!

It's from all the acid that loves inside ya guts.

Well, people don't tend to eat when they're dead. That helps a bit

And being covered with rotten acidic flesh has nothing to do with it

It's because when we're alive a ton of bacteria can live on your teeth and eat the sugars in your mouth which breaks them down. But when you die there's no more food for the bacteria, so your teeth remain as they were.