Process for Guided Bone Regeneration

By Hilarie Galloway, DMD

Guided bone regeneration (GBR) refers to a bone grafting process around a dental implant which includes using a membrane to exclude unwanted cell growth, allowing for the proliferation of slow-growing bone cells. This procedure is often necessary in sites where dental implants will be placed and may be combined with the implant placement or completed before the implant (or after, in repair cases), depending on the specific case. 

It is estimated that up to 40% of implant cases require GBR, which is specifically indicated in cases of large bony defects or loss of one or more bony walls. Such bony defects can occur due to tooth extraction, trauma, or periodontal disease. In these cases, restoring bone density and volume is important to achieve implant stability and success. 

Improvements in dental technology, including different graft membrane materials and improved protocols, have allowed for improved patient outcomes in implant cases. However, the long-term outcome of implants with GBR is controversial, as reports of similar prognoses among implants with and without GBR have been published. Thus, it is important to follow a specific GBR protocol and only use GBR in certain cases where it is clearly indicated.

What is Guided Bone Regeneration?

Guided bone regeneration refers to bone augmentation around a dental implant using a membrane to prevent infiltration and growth of unwanted cell types (primarily soft tissue), allowing for the growth and proliferation of slower-growing bone cells. Arguments exist about whether a membrane is required to qualify for the term GBR, or whether any bone graft around an implant is sufficient. 

Bone regeneration requires angiogenesis and the proliferation of bone cells (osteoprogenitor cells that differentiate into osteoblasts for bone formation) in the region of the bone defect. Osteogenic cells replace the blood clot with bone. The membrane in GBR excludes soft-tissue cells from infiltrating the defect and specifically allows bone to form in the defect.

When Guided Bone Regeneration is Necessary

Guided bone regeneration is often necessary for bone augmentation when preparing for dental implants (or other prosthetics), specifically in cases of large bony defects (>2mm) or loss of one or more bony walls. This bone loss is typically due to periodontitis, trauma, or following tooth extraction. The primary difference between GBR and other methods of bone augmentation (e.g. distraction osteogenesis or sinus lift) is that GBR uses a barrier membrane to exclude soft tissue and promote bony growth/stability in a bony defect surrounding an implant.

The Materials Used in Guided Bone Regeneration

Barrier Membranes

Barrier membranes are used in guided bone regeneration to exclude unwanted, rapidly growing soft tissue cells from the region of regenerating bone. Barrier membranes can be resorbable or non-resorbable. Resorbable membranes are typically made from collagen that degrades over time, while non-resorbable membranes are made from materials that will not degrade, most often polytetrafluoroethylene (d-PTFE) either with or without titanium reinforcement. 

Resorbable membranes are more cost-effective and easy to use as they only require a placement appointment and do not need removal. Non-resorbable membranes have better mechanical strength and tend to result in improved space maintenance when compared to resorbable membranes, but they do require a removal appointment and have been associated with increased complications (such as incision line opening).

Bone Graft Materials

Several types of bone graft materials are used in guided bone regeneration procedures, including autologous bone grafts (autographs), allografts, xenografts, and synthetic materials. Autografts refer to graft tissue harvested from the patient’s body, often from jaw or chin donor sites. Allografts are bone graft materials that are gathered from a donor and processed for safety, such as freeze-dried bone allograft (FDBA) and demineralized FDBA (DFDBA). Xenografts are sourced from animals, most frequently bovine donors. Finally, synthetic grafts are lab-manufactured materials such as calcium phosphate, bioactive glass, and hydroxyapatite. 

Material selection may vary, depending on patient preference, healing rates, and specific defect size. Ideally, autologous bone is placed directly over a dental implant with allograft and/or xenograft or synthetic materials as an outer layer for a large bone defect. This allows for the ideal bone healing of the autograft combined with the lower resorption rate and lack of a large donor site from the other bone graft sources to combine with an excellent outcome.

Additional Biomaterials

Additional biomaterials that are frequently utilized in guided bone regeneration include growth factors such as bone morphogenetic proteins (BMPs), platelet-rich plasma (PRP), and platelet-rich fibrin (PRF). Bone growth factors help to improve bone formation and healing by allowing for the differentiation of undifferentiated mesenchymal cells into bone cells. When added to the barrier membrane and/or bone graft, these factors have been found to increase angiogenesis, the surrounding soft tissue, and bony healing.

The Step-by-Step Process of Guided Bone Regeneration

1. Diagnosis and Treatment Planning

As with any dental (or medical) treatment, the first step is a thorough exam and patient consultation to determine whether the patient is a good candidate for guided bone regeneration. This exam should include diagnostic imaging, such as radiographs and 3-dimensional CT scans, to assess the severity of bone loss and determine a specific treatment plan. 

In many cases, the treatment plan will include collaboration between a general dentist and dental specialists, including periodontists or oral surgeons. The treatment plan should always consider specific patient circumstances, including overall health, bone quality, and future treatment needs (including implants).

2. Surgical Procedure

Pre-operative Preparation 

There are several pre-operative considerations for patient preparation. The patient must maintain good oral hygiene to minimize bacteria in their mouth at the time of surgery. They should also review their use of medications with their dentist/surgeon, including prophylactic antibiotics if indicated.

The surgeon will discuss options for anesthesia with the patient, with options varying from local anesthetic only to general anesthesia depending on the patient’s needs. Either way, a local anesthetic is necessary for patient comfort.

Incision and Flap Creation

Flap design and creation are key to the success of any guided bone regeneration procedure. The gum tissue must be carefully opened to expose bone (and bony defect) while maintaining blood flow to the gingival flap. The coronal incision should be at or lingual/palatal to the bony crest of the ridge, with vertical release incisions on the buccal side of the ridge extending to the level of the mucogingival junction. 

The release incisions should create a broader flap at the mucogingival end of the flap than at the coronal incision, to maintain blood flow. A clean, continuous incision through the gingiva and periosteum to the level of the bone is critical to proper healing following surgery. The tissue flap should be entirely released of tension and include layers from surface mucosa to periosteum to prevent complications such as incision line opening during healing.

Preparation of Defect Site

The bony defect site must be cleaned of all soft tissue remnants and infectious material. The bony surface should also be smoothed to prepare it for grafting. The cortical bone should have small holes prepared in the surface (decortication). This allows for improved blood flow from underlying trabecular bone and has been shown to speed healing of the bone graft site.

Placement of Bone Graft Material

The bone graft material is now packed into the bony defect site. For predictable space maintenance, titanium tenting screws are often placed into the graft site to hold the membrane apart from the graft site while healing occurs. 

In larger defects (over 3mm), autogenous bone should be placed directly on the patient’s implant or graft site bone, with allogeneic bone (or xenograft or synthetic bone graft) condensed in small increments over the autograft and packed around tenting screws in the graft site. In smaller defects, the autogenous bone is not necessary. 

The bone graft should act as a scaffold for bone regeneration and new bone growth with increased angiogenesis to the area and growth factors stimulating osteoprogenitor cell differentiation. This is specifically allowed using a barrier membrane that excludes unwanted, faster-growing soft tissue cell invasion into the bony defect during healing.

Positioning of the Barrier Membrane

The barrier membrane must be carefully positioned over the bone graft to prevent soft tissue cells from interfering with the bony healing process. The membrane should be large enough to cover the entire graft site while extending 2-3mm beyond the site. 

For optimal results, the membrane must be secured in place—this is often accomplished by using bone tacks (typically on the lingual/palatal side of the ridge) but is sometimes achieved by tucking membrane edges under flap margins during closure.

Suturing and Protecting the Site

Additional site stability is gained by closing the flap over the graft and membrane with sutures. During this step, it is critical to ensure that no flap overlap occurs and that no bone graft material is present in the flap margins. 

3. Post-Operative Care and Healing

Immediate Aftercare

Immediately following a guided bone regeneration procedure, patients should expect minor bleeding, swelling, and pain. To control bleeding, pressure should be applied with a clean gauze (changing every 30 minutes or so) until the bleeding stops. Placing an ice pack against the face in the surgical site area for 20 minutes on and off throughout the day following surgery can help control swelling. Pain medications should be taken as prescribed for pain—many patients will not require prescription pain medications and should take ibuprofen or acetaminophen as needed to improve pain. Some surgeons will prescribe antimicrobial mouth rinses or antibiotics for infection prevention—these should be taken and prescribed. 

Immediately following surgery, the site shouldn’t be cleaned directly, and a soft diet should be followed to avoid disturbing the surgical site with hard foods. If bleeding, swelling, or pain occurs that is concerning to the patient, they should always contact their dentist or surgeon. Similarly, patients should always defer to their provider’s instructions for specific post-operative care.

Monitoring the Healing Process

Complete healing of the graft site should occur within roughly four to six months, although initial healing should occur within several weeks of the procedure. Follow-up appointments and radiographs are important to monitor healing and graft integration/new bone formation. Throughout the healing process, it is important that the patient follows the provider’s instructions and maintains good oral hygiene to prevent healing disruption and minimize the chance of infection.

Long-Term Care

Following healing, the membrane will resorb or be removed by a dentist or surgeon (depending on the type of membrane placed). Once this is complete, the patient will be prepared for the next phase of treatment, which may include dental implant placement. For greater long-term success, patients should maintain good oral hygiene, follow regular maintenance appointments, and avoid smoking and other behaviors that can negatively impact oral bone levels. 

Benefits of Guided Bone Regeneration

Dental Implant Success

Guided bone regeneration can help increase the chance of success in dental implants by ensuring a strong foundation for dental implants. Although data on long-term prognosis following GBR vs non-GBR cases is conflicting, GBR in cases of bony defects larger than 2mm has been found to reduce the risk of dental implant failure by restoring adequate bone volume and density.

Improved Aesthetics

Guided bone regeneration can also help to improve aesthetics in some cases. When natural jawline contours have been affected by bone loss, GBR can be used to improve bony contours. This can be particularly beneficial for patients with concerns regarding facial asymmetry following tooth and bone loss.

Minimally Invasive Compared to Alternatives

Compared with other bone augmentation procedures (including distraction osteogenesis and block grafting), guided bone regeneration is less invasive, involves faster recovery times, and reduces risk of complications.

Long-Term Oral Health

A long-term benefit of guided bone regeneration is that GBR allows for implants to be placed (or stabilized), which helps to preserve bone levels over time. This, in turn, reduces arch collapse and allows for healthy jaw contours to persist.

Risks and Considerations

Possible Complications

The most common complications following guided bone regeneration are membrane exposure and wound dehiscence. These complications can cause infection, poor healing, bone formation reduction, and graft loss. As infection can cause graft failure, using sterile instruments and materials during surgery is important. Similarly, following proper technique, especially flap design, is critical to success and avoiding membrane exposure. 

Success Rates

Implants placed following properly executed guided bone regeneration generally showed high success rates (79-100% depending on the source), with rates similar to conventional sites not requiring GBR. Success rates depend on individual patient factors, specifically compliance with follow-up care and not smoking, as well as overall patient health.

Patient Responsibilities

Patient responsibilities following guided bone regeneration include following aftercare instructions provided by the surgeon. Patients must also maintain regular oral hygiene and dental exam appointments to maintain bone health and reduce the risk of complications.

When to Consider Guided Bone Regeneration

Common Scenarios

Guided bone regeneration is commonly considered in several scenarios. Often in cases where dental implant candidates lack sufficient bone density or patients have significant bone loss caused by periodontal disease, GBR is a good option. 

Guided bone regeneration can also be considered for ridge augmentation to improve prosthetic placement and aesthetics. GBR is also often used in cases where bone preservation is necessary following tooth extraction. Guided bone regeneration success rates are most significant when the graft is placed in a more than 2mm bony defect.

Eligibility Factors

Not all patients will be eligible for guided bone regeneration. To determine individual patient eligibility, the dentist or surgeon will evaluate the patient’s health status and specifically look at situations that may decrease healing ability, such as diabetes, advanced age, and smoking. Following proper protocols and patient selection criteria will help to ensure a successful outcome and improve long-term prognosis.

Stomadent Dental Lab’s Role in Guided Bone Regeneration

Support for Dental Professionals

Stomadent Dental Lab provides support for dental professionals. Stomadent offers high-quality bone graft materials and other biomaterials often used for successful guided bone regeneration. We also offer customized solutions tailored to specific patients, ensuring precision and more effective treatments. Stomadent partners with dentists and oral surgeons to deliver optimal patient outcomes.

Commitment to Innovation and Quality

The technology and materials used in bone grafting are constantly improving. Stomadent knows the importance of remaining at the forefront of dental technology to ensure successful outcomes. 

Why Choose Stomadent Dental Lab?

Stomadent Dental Lab offers unparalleled expertise in dental restorations and regenerative solutions. With a focus on providing reliable, high-quality materials that deliver consistent results, Stomadent is an excellent resource for dental practitioners.

Guided bone regeneration can be beneficial in restoring bone density and improving clinical outcomes in dental implant cases, specifically where bony defects larger than 2mm are concerned. Stomadent Dental Lab supports dental professionals through high-quality regenerative materials and the latest technological advancements. 

To learn more about Stomadent Dental Lab and the support we offer dental professionals and patients alike, visit our website to learn more about bone graft materials and implants.