Periodontal disease

Periodontal disease is a group of problems affecting the periodontium, the structures that hold the tooth in place. These include the gum; the alveolar bone, the part of the bone that houses the root; the cementum, which covers the root; and the periodontal ligament, which anchors the root to the bone.

Its mildest form is gingivitis, or inflamed gums. It develops when bacteria and debris build up. Periodontitis goes further and gradually damages the periodontium: the junctional epithelium, the seal where the gum attaches to the tooth, shifts toward the root, and a gap opens between tooth and gum, called the periodontal pocket.

And here is the curious part. When bacteria get in deeper, the body sends its immune response to fight them, and that same defense unintentionally helps destroy the periodontium. Attachment is lost, meaning the tooth is less firmly anchored, the alveolar bone is resorbed and, in severe cases, the tooth is lost. It is like a post with no firm ground.