I agree with Carol. Once you put your chin on a high quality pellet, you should be able to see improvement with teeth/overall health. But it is not going to fix the situation your chin is in right now. The only time I used a Vit B supplement was when one of the chins had a URI and the vet had recommended it in addition to the vit C he was getting from rosehips.
Some high quality pellets include Mazuri, Oxbow, American Pet Diner, etc. Some of these feeds you can find at your vet, local petstore, or even in the classifieds here on the forum. Good luck.