My dog has broken a toenail a week ago. He seems much better, I have kept him inside and disinfected it every time he goes outside to use the...

Hello! Fish oil and biotin supplements can promote healthy nail growth. I would give your vet a call to see if they have any they recommend since they know your pet and his medical history. On certain occasions, if there was damage to the actual nail bed, there is a chance that the nail may never grow back correctly. If that is the case, I would monitor that nail closely and keep it trimmed to reduce the risk of it splintering off. If you notice any oozing or odor from the nail, I would have him checked out by the vet. Hope this helps! 

Bandaging likely won't help his nail grow back properly. Usually we will bandage the nail the first day it happens just to protect it from getting infected more than anything, and have the bandage removed after about 48 hours. As I stated in my previous response, if there was damage to the nail bed itself, there's a chance it won't grow back properly (as in it may always look different from the other nails, grow in a different direction, or may always appear delaminated). If the nail has already broken off, but he seems to be doing ok otherwise, it's just going to take some time for it to heal and grow back. If you notice in another week or so it still appears to be splitting, he may need to have it removed fully (or cut back further than the delamination) if it is causing him pain, he continues to break it, or things are getting stuck in it (carpet, dirt, etc.). It is hard to tell at this point if his nail is damaged long term.