When teeth are lost, the underlying bone (alveolar bone) is likely to resorb (shrink) both vertically and horizontally. The alveolar bone supports the teeth and when it no longer receives stimulation from forces on the teeth, it tends to melt away. Areas with teeth that have been missing for a long time, and/or have been prosthetically replaced with removable dentures, will often have so much bone resorption that there is not enough remaining to be able to place implants of adequate size.
Similarly, teeth that have been lost due to advanced periodontal disease (gum disease), will often have experienced so much bone loss that there is not enough bone remaining for implants to be placed. Bone defects from root canal infection, fractured teeth, trauma, or difficult tooth removal may also create a situation where bone needs to be augmented (replaced by means of grafting) for implant placement to be accomplished.
Bone Grafting Materials
There are many types of bone graft material currently available and research promises more to come. Some surgeons may elect to use a patient’s own bone, harvesting it from nearby areas, sections of the patient’s lower jaw, or harvesting it from the knee or hip (both of which have readily accessible and large amounts of bone available).
Other commonly used types of bone are derived from cow bone that has been processed to remove protein and acts as a stimulus for the body to replace it with new bone. Human cadaver (allograft) bone can also be used, as well as several forms of synthetics. Recently, a product utilizing recombinant gene technology-derived protein (bone morphogenic protein) has been introduced to the dental market and is FDA-approved for use in sinus grafting and certain types of ridge augmentation. Expect more to come!