Moving or loose teeth can be late warning signs for advanced periodontal disease.

It usually indicates a significant destruction of the support structure of tooth/root (the periodontium) --- often as a result of long term exposure to untreated or uncontrolled periodontal disease.  Apart from causing un-aesthetic appearance, untreated periodontal disease is the most common cause of tooth loss in the developed world.  Other common symptoms associated with periodontal disease are bad breath (halitosis), unpleasant taste and spontaneous bleeding of the gums.