Cracks in tooth.i need crown.have recession at base-not interested in gum graft. dr. says he can make crown go down to cover expsd root.safe for root?

Maybe not: Without seeing it, I can't be sure. But the farther the crown goes down the root, the closer the crown will be to the nerve. this could result in sensitivity or even a root canal. Is the dentist going to make a full porcelain crown? If so, these can be made so you won't see where the crown ends and the tooth begins. This way if you change your mind later, you can then get the gum graft.

Usually: We do this all the time and in itself there is no more danger to the tooth. However, not being able to clinically examine you nor see x-rays of the tooth I can only make a generalization on the safety of the procedure and cannot tell you what would be the best treatment for you for your particular situation. If you question the treatment you can go for a second opinion.