You can have a look at Ling Jie's toothpaste. It's good. There are many kinds of effective toothpaste. I suggest you use their toothpaste to improve the problem of black and yellow teeth. This toothpaste is specially designed for tobacco stains, coffee stains, tea stains and other problems. It can effectively improve the black and yellow teeth and make them white. My father also smokes. I just bought it for my father. My father's teeth are much whiter now.