Don't know if i want to use this fluoride stuff my dentist recommended to get rid of the hard white plaque stuff. is it safe?

Yes: As long as you do not swallow it.

Have hygienist scale: Fluoride strengthens teeth, especially while teeth are undergoing development in children. It has very little impact on white, soft plaque that has abosorbed the minerals in your saliva to become hardened (essentially fossilized) calculus. Don't try to brush this hard material away. It won't work and your gums may get damaged in the process. Get a hygienist to scale it off. Then floss daily!