This short question has provoked a rather elaborate response...

When teeth are extracted, there is an accompanying loss of a good portion of the bone matter which keeps the teeth in place.

In fact, once the teeth are extracted, the bone that encircles them is rapidly reabsorbed and loses its volume. The roots of teeth naturally transfer the forces of mastication to the bones of the jaw, giving them the necessary stimulation for constant reconstruction. If these roots are absent, the bone is no longer exercised and the lost volume must be replaced either by a larger prosthesis or by a reconstruction bone graft. This is an important factor which must be considered in the choice of the treatment in implantology.

Jawbone with natural teeth.         Extraction of all the teeth.         10 years after teeth extraction. The wear and tear caused by wearing false teeth causes a thinning of the jawbone which supports the gums.         30 years after teeth extraction. Thinning of the jawbone which supports the gums due to the wearing of a dental prosthesis without support.