Will general cleaning of gum prevent loss of tooth and bone?

Usually: Tooth and bone loss usually occur because of the bacteria which builds up in your mouth. Regular oral care at home and a professional cleaning every 6 months will eliminate or minimize the bacteria and prevent the subsequent tooth and bone loss.

Yes: Yes that is why a general cleaning is recommended every 6 months as you cannot get under the gums where plaque can accumulate which causes the bone loss. If you do have a lot of plaque and tarter under the gums, than you may need a more aggressive cleaning called scaling and root planing. In that case a general cleaning will not help until you get the scaling.