I know the smiles are supposed to be creepy but everytime I see one that doesn't show any teeth I'm like "Where's your dentures? Did you lose them again?". To be honest I'm actually surprised that apparently most shinobi still have all their teeth. Either teeth are not often punched out or with their chakra cheats they naturally regrow them like crocodiles or sharks.
I have seen a few fics where shinobi or anyone who uses chakra can naturally regrow stuff like cartiledge which can't regrow irl. I have also seen one where Hashirama's regeneration gave him cancer due to how rapidly his cells reproduced and every time they tried treating it with chakra it made it worse. Every time they gave his cells to someone it was essentially just transfering aggresive cancer from one person to another, basically acting like a type of disease. If more fics went along this route I would not be surprised if Hashirama's body lived on long after he died, essentially acting as patient zero for a plague. Truly the opposite of Hashirama's dreams for peace.
Alright, the teeth thing is actually very valid, lol.
Both Ghost Kitsunedara (especially him actually),
have teeth. The reason why they got creepy hollow smile, for Ghostdara is just because he is not really tangible like a person. His image shifts, he is just chakra floating, his form will change depending on what he feels, so it's a raw projection of his being, if you will. Some emotion end up, because of this odd condition, to show in a simpler way, like if Madara himself just drew his own expression on his face.
For Ghost Kitsunedara, on the other hand... it's more intentional, let's say. He can have a very human like appearance to sooth and lure preys. The flip side is, to intimidate, he can take on a less attractive face.
Sometimes, he doesn't do it on purpose, a bit like Ghostdara, but instead of being from a raw emotion he has trouble expressing, it's more from a feeling of emptiness.
See it like that, sometimes, Ghostdara will drown in his own emotions and they will appear less refined, and Kitsunedara will choke from the lack of emotions, carving out a simple smile as an attempt to regain control and feel something.
Kitsunedara can also just have no face at all (he is also mostly chakra, at this point, it's the reason he can change his appearance so easily as well)
Now, for the teeth issue in Naruto, I think shinobi do lose teeth a lot. I had a line abt Madara learning to avoid getting hit in the face during training with his father and Izuna noting how he lost some teeth, and that he was lucky those would grow back. The thing is that, getting hit in the face is often a death sentence. It's very vulnerable, a broken nose can knock you out, and you're dead, eyes are sensitive and an essential sense... you get the gist of it, the first worry wouldn't be losing teeth, but more, staying alive.
Now, for those who did get out alive but with some lost teeth, I'm sure they could replace them. Not regrow, we humans don't regrow teeth as far as I'm aware, but fake teeth have been around for a while.
Also the fact that they can lose teeth less easily with chakra is probably another reason I'd agree with (just not the regrowing teeth thing, except Hashirama, I don't think so lol)
(Fun fact, my Madara has some back teeth missing, but it was from an event unrelated to the battlefield)
For the fic part, it's probably just my own headcanon, but I don't make medical nin able to regrow everything and anything (I feel they'd be overpowered if so) but that's just how I write it. My only exception is Hashirama, but only on himself, and it's mostly the not quite human part of him that is the reason he's like that.
Although I don't share this headcanon, the Hashirama's cell acting as cancerous ones and it destroying himself with time is something I enjoy reading. Very angst material >:)
I write him more as a parasite, but this idea of his body living long after his own death, as a disease spreading and killing folks, is a really cool concept.
So... drop the fic name pls, gimme gimme the yummy Hashirama angst.
