Blind Man, 34, Can Now See After Having His Tooth Implanted in His Eye in 'Science Fictiony' Surgery

I wondered that as well. With normal bone there's a cortical layer on the outside - solid/dense, and a cancellous core that's kind of spongy. Teeth are similar, but I don't know much about what makes them different from regular bone other than the enamel which doesn't appear to be a factor here since they shave all that off anyway.

Since they're just sticking in a chunk of tooth with a hole drilled in it, it wouldn't be able to open or close like an iris... functionally all I can tell they're doing is inserting a fixed aperture for light to pass through, so my question is why bother with a biologic prosthesis in the first place? Bone or tooth both seem like a lot of unnecessary* steps when we could just do basically a cataract surgery and replace the lens with an otherwise normal synthetic lens prosthesis that we use all the time; except with an opaque ring made of something stable like a titanium foil which would provide that same fixed aperture.

*I'm just a tech, and I've never done one of these in person, and intraoperatively is when I get to pick surgeons' brains about all the why's behind the operation. So, don't put any weight into it seeming unnecessary to me - I'm sure there's a reason, it's just over my head at this time.

Your canines, so called because an optic nerve runs near them and can cause brain freezes and similar effects when they get chilled.