Periodontitis is a general term for diseases affecting the periodontium. Especially, the first stage of periodontitis is called gingivitis. At this stage, only inflammation of gum is occured. At the higher stage, called periodontitis, inflammation extends to the other tissues of periodontium. In the early stage, periodontal disease has few symptoms and it is easy to worsen without notice.

See the symptoms of periodontitis below.
- Bleeding gum in brushing or eating something hard
- Sticky in the mouth on awakening
- Bad breath
- Swollen or softened gum
- Discolored gum (from pink to red or purple)
- Spreading interdental gap that more food sticks in
- Feeling of being the longer teeth or protruding teeth
- Pain or Itching of gum
- Gum forming pus
- Unstable teeth

As periodontitis , by the bacteria erosion, the clearance between marginal gingiva and tooth (gingival sulcus) will be deeper and deeper. The deeper gingival sulcus called periodontal pocket. In good condition, gingival sulcus has a depth of 0.5 - 2.0 mm.

At the stage of gingivitis, inflammation occurs in gingival sulcus and you will bleed from the swollen boundary between teeth and gum. Periodontal pocket has a depth of 2-5 mm. Inflammation occurs only in gum not in other tissues of periodontium. At this stage, by removing dental plaque and receiving appropriate treatment, the condition is able to be restored. However, with no action, dental plaque holding a lot of bacteria will invade the pocket and the deeper areas of periodontium will be eroded.

At the first stage of periodontitis, the depth of periodontal pocket is more than 3 mm. Inflammation occurs in PDL or alveolar bone and periodontium begin to be destroyed. More and more dental plaque is piling up in the pocket and the range of inflammation is expanding.

At the second stage, the depth of periodontal pocket reaches more than 4 mm. Inflammatory disorders is expanding to the half of the root. 1/3 or more of the alveolar bone are destroyed and the stability of the tooth begin to be decreased.

At the last stage of periodontitis, periodontal pocket has the depth of more than 6 mm. 1/2 or more of the alveolar bone are destroyed and the tooth has few stability or be lost. At every stage of periodontitis, it is indispensable to have medical treatment. However, the last stage requires not only medical treatment but also surgical one.