How can periodontal pockets decrease if the damage is permanent ?

Bone loss..: .. Is permanent. The level of the bone will not grow back, so that damage is permanent. The gum tissue, through treatment (surgical and non-surgical) can recontour, decreasing pocket depth.

Perio treatment: can promote reattachment of healthy gums to teeth, reduce inflammation, swelling, the depth of pockets, and the risk of infection, and also stop further damage and tooth loss. See a periodontist for consultation.