[spidey]

It should probably be extracted, what you can see inside there is the pulp of the tooth, which means that there is now a direct contact between the outside and the dog's bloodstream - a tooth broken like this is a risk for serious infection, as well as damage to the tooth bud of his adult (permanent) canine tooth. This is an important tooth, and if this were my dog, I would have the broken baby tooth extracted (BY A COMPETENT VET TRAINED IN DENTISTRY) asap (my puppy broke the big premolar and I had that extracted, now her adult tooth is gorgeous - BUT she only had the broken tooth for a few days and already she had changes in her liver values on bloodwork related to infection, which resolved afterward - infection from broken teeth is very common).