The team believes that in the future it may be possible to grow teeth not only in people with congenital conditions, but also in those who have lost teeth due to cavities or injuries.

Quote from the article. This medicine doesn’t actually regrow teeth, it deactivates a protein that prevents existing tooth buds from developing into teeth due to some congenital conditions. If you have lost a tooth that had already developed then the tooth bud is gone and this treatment isn’t expected to restore a missing tooth bud. This is a step toward regrowing lost teeth but without a way to generate a new tooth bud this isn’t going to get us there.