Sometimes the roots don't dissolve properly, and instead they fuse directly to the jawbone. The fusion may occur because the ligament that normally surrounds the tooth in the jawbone is lost. This condition is called ankylosis..
The causes for ankylosis vary; for example, the healthy ligament cells may dry up and die because any of these.
Doctors suggest that an ankylosed tooth be removed as early as possible. One simple technique to isolate a healthy tooth from a ankylosed tooth is to tap it with finger and hear the sound. A healthy tooth makes cushioned sound, where as an ankylosed tooth makes a dull sound. Surgery with special instruments can treat this dental problem in children.