When a tooth is removed, socket preservation (or alveolar ridge preservation) may be recommended. This procedure involves placing bone graft material directly into the empty socket immediately following the extraction. The primary function of this technique is to maintain the volume and contour of the jawbone, preventing the natural collapse of the bony walls.
Why Bone Grafting is Recommended
The alveolar ridge is maintained by the tooth root, which stimulates the surrounding bone tissue. Once the tooth is removed, this natural stimulus disappears, and the body initiates disuse atrophy. This results in the rapid and significant loss of bone structure around the extraction site.
This process, known as alveolar ridge resorption, is most intense immediately following the extraction. Studies show that two-thirds of the dimensional changes occur within the first three to six months. Within the first year, the jawbone can lose up to 50% of its width.
The loss of bone is not uniform; it is often more pronounced on the outer (buccal) side of the jaw. This anatomical change reduces both the height and width of the remaining bone, altering the overall contour. Socket preservation creates a scaffold that preserves the space and shape of the socket, significantly reducing this natural bone shrinkage.
Placing the graft material encourages the area to heal with new bone tissue instead of allowing the socket walls to collapse inward. This stabilizes the soft tissues (gums), maintaining a more natural gum line. Not performing this step results in a diminished ridge, which can complicate future dental restorations.
When Is Grafting Essential
Determining if bone grafting is necessary depends on the patient’s plans for future tooth replacement. If replacement is desired, preserving the bone volume is necessary for a predictable and successful outcome. Sufficient bone is required for a stable foundation for prosthetic components.
A graft is mandatory when the patient plans to receive a dental implant. Implants are titanium posts that must fuse with the jawbone, a process called osseointegration. This fusion requires a specific volume and density of healthy bone to ensure the implant is stable and can withstand chewing forces. Without adequate bone height and width, an implant cannot be placed or risks failure.
Preparation for a fixed bridge often requires a graft for an optimal aesthetic result. A fixed bridge uses an artificial tooth (pontic) suspended between two crowns. If significant bone is lost, the gum tissue recedes, leaving a gap beneath the pontic. Grafting maintains the underlying bone structure, ensuring the replacement tooth appears to emerge naturally from the gum line.
Grafting is also essential for patients who plan to wear a partial or full denture. Dentures rely on the underlying bone ridge for stability and support. A diminished or uneven ridge caused by bone loss can lead to a loose-fitting denture that causes friction and discomfort. Preserving the ridge contour ensures the denture fits securely and functions more comfortably.
Understanding the Grafting Process
Socket preservation is typically performed immediately following the tooth extraction while the patient is anesthetized. Once the tooth is removed, the empty socket is carefully cleaned to prepare it for the graft material. This material acts as a temporary matrix, guiding the body’s natural bone-forming cells.
Various types of grafting materials are available, serving as a scaffold for new bone growth. These include:
- Autografts, which use the patient’s own bone.
- Allografts, derived from human donor bone.
- Xenografts, sourced from animal bone (often bovine).
- Alloplasts, which are synthetic bone substitutes.
All materials are rigorously sterilized and processed to ensure safety and compatibility.
The granular graft material is packed into the socket, filling the void. The surgeon then places a barrier membrane, often made of collagen, over the graft. This membrane prevents the faster-growing soft gum tissue from migrating into the socket space before the slower-growing bone cells have a chance to fill the area.
The site is closed with sutures to hold the material and membrane securely in place. The initial healing phase, involving the gum tissue, takes a few weeks, but internal bone regeneration takes much longer. The graft material is gradually replaced by the patient’s own mature bone over three to six months, at which point the site is ready for the final restoration.