There's all sorts of weird relationships between sharks and other fish. Like the fish that live off by performing dentistry for sharks inside their mouths.
There's also a type of shrimp that cleans even human teeth. I first saw it on a dive where our guide casually removed her regulator and they approached quickly. Here's how it looks (not my video):
Amazing! The evolutionary pathway of the sharks that didn't chomp and the Cleaner Wrasse that had the guts (or the lack of flight response?) to go near a sharks mouth is astonishing.
https://www.youtube.com/watch?v=V5EszU8yuA8