Your teeth are held in place by their roots in the jawbone. Tooth decay, disease, or trauma may have caused the loss of several teeth. Immediately after tooth loss, the jawbone will begin to resorb or shrink. Over time, the ridge of the jawbone becomes much thinner, limiting the options and possibilities of tooth replacement.
The remaining teeth no longer have the support that the lost teeth and bone provided. With no support, the teeth begin to drift (arrow Indicates Direction of Drifting) and erupt toward the open areas. The overload can move and weaken those teeth, possibly leading to additional tooth loss.
How much bone loss and drifting going take place will vary from person to person. It depends on many factors such as which teeth are missing, and the individual's health, and many other factors. If several teeth are missing, a lot of space is created and may allow significant drifting and bone loss.
When teeth drift and erupt, gum disease may start to form, as it becomes harder and harder to properly clean your teeth and gums. Gum disease can lead to sensitivity and pain, making it even harder to brush and clean properly, and can also lead to tooth decay, gum recession, and even further tooth loss.