Sometimes the disease is rapid. However often the disease takes a long time to develop. The linked documents provide some information about gingivitis and periodontitis and the material also show the effect of successful t reatment. The pocket around the tooth, a perfect hiding place for the bacteria. Left undetected, never or seldom cleaned, then the bacteria thrive and multiply.
Bacteria cause the inflammation.
The inflammation gradually destroy the tooth attachment. Early periodontitis in a 30 year old female. She has noted bleeding from the gums now and then for a couple of years. However she has not received any treatment for the disease at her regular dental care visits. Friends have now told her that the bleeding from the gum might be a sign of periodontitis and she is worried for her oral health.