How to help your baby have healthy teeth?

In our hometown, there is such a method: wring the white gauze dry with water and gently wipe the baby's gums, because the gums will itch when the baby is about to teether, and wiping can relieve it. There is also something that can't be given to children. The old man said that his teeth were not good. Well, that's what I heard from the old man. I hope a professional can explain whether there is any scientific basis. Thank you.