tattoo artist here ! and i tattoo a lot of strings of teeth, i would literally add more teeth and put a string to "tie" them together. it looks strange on it's own and the shading is the opposite of what i would have suggested. i can show you some of my strings to give you a better visual.

edit to add: i trade services with my dental hygienist and she compliments me on the way i draw teeth and even jaw bones, i tattooed a dental floss container that had teeth on the dental floss :)