Of course the best cure for periodontal disease is to try to prevent it from happening.  This means removing plaque at home effectively,  having dental exams and x-rays routinely and having teeth cleaned professionally at regular intervals.

In dental school, students undergo a self-experiment:  They go a week without brushing and flossing and in that week, gingivitis develops.  Then,  they take a week and floss and brush (this may be uncomfortable once inflammation has developed but it is worth the discomfort).  In a week, the disease reverses and without the plague to infect it, becomes healthy again.

After bone is affected the disease needs additional treatments.  The dentist will need to record the depths of any pockets and  monitor the disease.  Thorough cleaning in the pockets and root surfaces, called root planing, will probably be needed.  Sometimes there is so much calculus to be removed that the gum may need to be flapped back a bit to allow the dentist to get access to it.  There are other treatments and the plan must be individualized for each patient.  Sometimes, antibiotics can be very helpful to kill destructive bacteria deep in the pockets.  Sometimes various surgeries are an option.  If periodontitis is early, treatment may be relatively simple.  If it has progressed so that bone loss is serious,  treatment may involve extractions and/or  implants, bite guards,  root canals and surgeries.

The general dentist can adequately treat most types of early periodontal disease.  However,  there are times when it may be better to see a periodontist, or gum specialist.  If a general dentist does not have the time or interest in periodontal disease,  a specialist or another general dentist may be needed.  Where a lot of bone is missing,  or if a patient has special health problems, a specialist may be needed.  Some patients may prefer to see a periodontist in the early phases of the disease for preventative treatment.