While natural teeth are embedded in the jawbone, they transmit vertical “pulling” forces to the bone via periodontal fibers during chewing; this vertical stimulus keeps bone cells (osteoblasts) alive and preserves bone volume. However, when teeth are extracted and replaced with a removable total (denture) prosthesis, the situation is completely reversed. The removable prosthesis transmits the chewing force not as vertical pulling to the bone, but as a direct “superficial pressure and compression” force through the mucosa. When bone tissue is constantly under pressure, the microvessels in that area constrict, nutrition is impaired, and bone-resorbing cells (osteoclasts) are activated. As a result, the jawbone gradually and insidiously resorbs and flattens over the years. As the bone resorbs, the prosthesis loosens, begins to rub, and moves.
