Periodontal therapy is performed to try and stop bone loss around teeth
that have deep probing pockets and existing bone loss.  The main focus
is to remove plaque and tartar, which are the main factors that contribute
to bone loss.  In most cases it is not possible to gain back any of the
bone that is lost, but hopefully future bone loss can be avoided.

Scaling and Root Planing - As stated above, one of the most important
things is to remove tartar and plaque that will lead to irritation and more
bone loss.  This cleaning is a "deep cleaning", meaning that the cleaning
needs to be done in the deep pockets between the tooth and gum (a
place that no patient can effectively clean because of its depth).

Periodontal Surgery - These surgeries are usually done for access.  
Moving tissue so that a tooth can be effectively cleaned or tissue

Bone Grafting - In certain cases, if the bone loss around a tooth follows
certain patterns, it is possible to graft new bone into these defects,
resulting in a higher level of bone.
Periodontal Therapy