Dental implants are a popular and effective solution for replacing missing teeth, functioning as replacement tooth roots that provide a stable foundation for artificial teeth. These titanium posts are surgically placed into the jawbone, where they must form a direct, permanent connection with the surrounding bone tissue. This fusion process is the foundation for a successful and long-lasting outcome, and the quality and quantity of your jawbone are the most important factors in determining eligibility.
The Role of Bone and Necessary Dimensions
The biological process that secures the implant is called osseointegration. This involves the jawbone growing directly onto the titanium surface, locking the implant in place. This mechanism allows the implant to withstand the powerful forces of biting and chewing over many years. Without sufficient bone volume, the implant lacks mechanical stability, leading to failure.
Two specific measurements are evaluated before implant placement: the height and the width of the available bone. Bone height ensures the implant can be fully submerged and stabilized within the jaw. Adequate height avoids contact with the mandibular nerve in the lower jaw and prevents penetration into the maxillary sinus cavity in the upper jaw.
The width of the bone determines the amount of protective bone surrounding the implant post. Specialists aim for 1 to 2 millimeters of bone to completely encircle the implant fixture. A general guideline for a standard implant site is having at least 10 millimeters of bone height and 6 millimeters of bone width.
Common Causes of Jawbone Deficiency
Bone deficiency occurs because the jawbone requires stimulation to maintain its density, much like muscle tissue needs exercise. The most common trigger for bone loss is tooth removal, as the alveolar bone that supported the root is no longer stimulated. The greatest amount of bone resorption typically occurs within the first 18 months following an extraction if the tooth is not replaced.
Another frequent cause is advanced gum disease, or periodontitis. This chronic bacterial infection destroys soft tissue and, critically, the underlying bone that holds the teeth in place. The resulting progressive loss of bone tissue can leave the jaw severely compromised and unable to support an implant.
Trauma or injury to the jawbone can also result in localized bone loss or defects requiring repair before implant surgery. Furthermore, in the upper back jaw, the maxillary sinus cavity can expand downward after the loss of upper molars. This process, known as hyperpneumatization, often leaves insufficient vertical bone height for implant placement in that specific area.
Procedures to Restore Bone Volume
When a patient lacks the necessary bone dimensions, several predictable surgical procedures can be used to augment the jawbone.
Socket Preservation
The most preventative measure is socket preservation. This involves placing bone grafting material into the empty socket immediately following a tooth extraction. This procedure helps prevent the natural shrinkage of the bone ridge and maintains the site for future implant placement.
Ridge Augmentation
For areas with significant horizontal or vertical bone loss, a ridge augmentation procedure rebuilds the jaw ridge. This involves surgically lifting the gum tissue and adding bone material to increase the width or height of the jawbone. The bone material used can come from various sources:
- Autograft (your own bone)
- Allograft (donor bone)
- Xenograft (animal bone, usually bovine)
- Alloplast (synthetic material)
Sinus Lift
A specialized augmentation for the upper back jaw is the sinus lift, or sinus augmentation. This procedure gently raises the floor of the maxillary sinus, creating a pocket beneath the membrane where bone graft material is packed. A small height increase may use an internal approach, while substantial bone gain often requires a lateral window technique, which is a larger surgical opening.
These grafting procedures function as a scaffold, encouraging the body’s natural cells to grow new, living bone tissue. The healing time before an implant can be successfully placed varies depending on the type and extent of the graft. Socket preservation typically requires three to four months of healing. Extensive ridge augmentation or a complex sinus lift may require four to nine months, or even longer, for the new bone to fully mature and integrate.