IT HURTS LIKE CRAZY. I honestly headcanon that his teeth are chipped from all the bullying and abuse he's taken over the years. And in case you didn't know, if you have jacked up teeth, they hurt like hell if you ever bite your tongue. His tongue likely has 'battle scars' at this point.

...On an extra note, I also don't remember it ever being said that he ever sharpened his teeth, (PLUS, HAVE YOU EVER CHIPPED A TOOTH, THAT HURTS LIKE HELL) so I think that headcanon is complete bullshit. Like I said, it's more likely they're messed up from bullying...or he was just born with them like all magical anime boys with shark teeth.

I think about Souda's teeth an unhealthy amount, my bad.