A good dentist will be able to diagnose periodontal disease and how progressive it is by using a perio probe calibrated to millimeters. He will measure the distance the probe can go down between the tooth and the gum of each and every tooth. He will record the numbers on a chart and tell you if you need periodontal therapy. Dentists often cut corners on dental exams and do not use a perio probe to diagnose this disease. If your dentist has not done this, you should definitely question him and insist a more thorough exam or switch to another dentist.
Periodontal therapy is done by a dentist and a dental hygienist.
You will be scheduled for one or more intensive teeth cleanings called deep scaling. The hygienist will scrape all of the built up plaque and tartar that has accumulated down below the gum line. You have to get rid of the plaque so that your gums can get healthy again. The only way is scraping it off. Sometimes there is a lot of bone loss and periodontal surgery will need to be done to tighten up the gums around the roots or the tooth with sutures.