Overview

Dental bone grafting is a surgical procedure utilized to add volume and density to the jawbone, which may be necessary when bone loss has occurred due to reasons such as tooth extraction, periodontal disease, or other factors affecting bone density and structure. This procedure is often a prerequisite for dental implant placement, as sufficient bone volume is crucial for the stability and success of implants.

Several types of bone grafting materials and techniques are employed in dental applications. Autografts, where bone is harvested from the patient’s own body, are commonly used due to their high compatibility and reduced risk of rejection. Other materials include allografts, sourced from human tissue banks, and xenografts, derived from animal sources.

Various classifications of bone grafts and substitutes, including both natural and synthetic materials, have been critically studied and are available commercially. These materials exhibit different properties, such as osteoconduction, which supports tissue ingrowth and bone formation by acting as a scaffold.

The success and survival rates of dental implants are significantly influenced by the quality of the bone graft and the surgical technique employed. Techniques such as edentulous ridge expansion (ERE) and maxillary sinus floor augmentation are commonly used to enhance bone volume in specific areas of the jaw, thereby facilitating successful implant placement.

Quality assessments of studies on bone grafts and implants focus on factors such as study design, number of patients, type of graft, follow-up time, implant survival, and implant success rate. Advances in dental bone grafting techniques and materials have contributed to improved outcomes in implant dentistry, enhancing the longevity and functionality of dental implants.

Types of Bone Grafts

Various types of bone grafts are utilized in dental applications, each with unique properties and sources. The selection of bone graft material depends on multiple factors including the size, location of the defect or injury, and the specific requirements of the dental procedure.

Alloplastic Grafts

Alloplastic grafts are synthetic bone grafts made from materials like hydroxyapatite, a naturally occurring mineral component of bone, or bioactive glass. These materials are favored for their osteoconductive properties, biocompatibility, and the ability to be shaped and tailored to the defect site. Technological advancements have led to the development of growth-factor infused collagen matrices and other synthetic variants that promote bone regeneration.

Autografts

Autografts, also known as autologous or autogenous bone grafts, are harvested from the patient’s own body, typically from the jaw, hard palate, or chin. This type of graft material is considered the gold standard due to its osteogenic potential and minimal risk of rejection. Despite its effectiveness, autografts require a secondary surgical site, which can increase the complexity and recovery time of the procedure.

Allografts

Allografts are derived from human donors, other than the recipient, and are commonly used in dental bone grafting. These grafts can be obtained in different forms such as freeze-dried bone allograft (FDBA) and demineralized bone matrix (DBM). While allografts eliminate the need for a second surgical site, they do carry a slight risk of immune rejection and disease transmission, although these risks are minimized through rigorous screening and processing protocols.

Xenografts

Xenografts are sourced from species genetically different from the recipient, commonly bovine in dental applications. Deproteinized bovine bone is frequently used and is commercially available under names such as BioOss™. Xenografts are beneficial for their availability and ability to serve as a scaffold for new bone growth, although they may take longer to integrate compared to autografts and allografts.

Combinations

In some cases, a combination of different graft materials is used to optimize the strength and longevity of the graft. Mixing autografts, allografts, and xenografts can enhance the overall grafting success by combining the osteogenic, osteoinductive, and osteoconductive properties of each material.

Due to continual advancements in this field, the range of available grafting materials and techniques continues to expand, offering improved outcomes for dental implant patients and other restorative procedures.

Bone Graft Materials

Bone grafting materials come in a variety of forms and originate from different sources. These materials are employed to replace missing bone and facilitate bone regeneration, especially in dental, spinal, and orthopedic surgical procedures. The primary categories of bone graft materials include autografts, allografts, xenografts, and synthetic bone grafts, each having distinct properties and applications.

Autografts

An autograft, also known as an autologous or autogenous bone graft, is bone taken from the patient’s own body. This type of graft material is considered the gold standard due to its biocompatibility and high success rate, as it integrates well with the patient’s natural bone and promotes new tissue growth. Common donor sites for dental procedures include the jaw, hard palate, chin, and sometimes the hip.

Allografts

Allografts are derived from human donors other than the recipient. These grafts are typically obtained from cadavers and processed to ensure safety and compatibility. Allograft materials, such as demineralized bone matrix (DBM), are widely used due to their availability and ability to serve as a scaffold for new bone growth. However, they lack the osteogenic properties inherent in autografts.

Xenografts

Xenografts are grafting materials obtained from a different species, usually bovine. These materials are processed to remove any proteins that may cause an immune reaction, leaving behind a calcified matrix that supports bone regeneration. The most common xenograft material in dental applications is deproteinized bovine bone, commercially available as BioOss™. Xenografts have been observed to persist at the recipient site for extended periods, often up to two years or more.

Synthetic Bone Grafts

Synthetic bone grafts are manufactured in laboratory settings and include polymers, ceramics, metals, and composites. These materials are designed to mimic the properties of natural bone and can be customized to enhance their biological activity. For example, ceramics such as hydroxyapatite and tricalcium phosphate are combined with growth factors and bone marrow aspirate to promote bone formation. Additionally, polymer-based bone graft substitutes, such as Healos (a polymer-ceramic composite) and Cortoss (an injectable resin-based product), are used in various applications, including spinal fusions and load-bearing sites.

The ideal bone graft material should integrate seamlessly with the patient’s natural bone, encourage the growth of new tissue, and exhibit a low likelihood of rejection at the surgical site. Despite the development of numerous synthetic alternatives, autografts remain the preferred choice for many dental applications due to their superior biological properties and clinical outcomes.

Clinical Applications

Bone grafting plays a crucial role in the field of dental implants and periodontal treatments. It is frequently used to address bone deficiencies in various clinical scenarios, ensuring a stable foundation for dental implants and promoting periodontal regeneration.

Sinus Lift Procedures

One of the primary applications of bone grafting in dental practice is during sinus lift procedures. This technique is particularly beneficial for patients with insufficient bone height in the posterior maxilla, where traditional dental implant placement might be challenging. The maxillary sinus lift procedure, initially introduced by Tatum H in the 1970s, involves creating an opening in the lateral wall of the sinus and gently lifting the Schneiderian membrane to place the bone graft and implants of suitable length. This procedure aims to increase the bone volume in the upper jaw, making it possible to securely place dental implants.

Ridge Expansion

Ridge expansion, also known as ridge splitting, is another significant application of bone grafting. This technique is employed to increase the width of the alveolar ridge, which is often necessary following tooth extractions. By using tools to cut and spread the bone, graft materials are placed to build up the ridge, providing adequate support for implants. Ridge expansions can be performed alone or in combination with other procedures, such as maxillary lift surgery, to address more complex cases.

Guided Tissue Regeneration

Bone grafting is also essential in guided tissue regeneration (GTR) for periodontal therapy. This method aims to treat inflammation and destruction of periodontal tissues by promoting the regeneration of bone and soft tissues around teeth. By combining bone graft materials with barrier membranes, GTR helps restore the function and aesthetics of the periodontal tissues, providing a comprehensive approach to treating periodontal intraosseous defects.

Use of Bone Graft Materials

Various bone graft materials are utilized in dental applications, including autografts, allografts, xenografts, and synthetic variants. Each material has its advantages and specific clinical indications. For example, autografts, derived from the patient’s own body, are often considered the gold standard due to their osteogenic potential. On the other hand, allografts and xenografts are valuable alternatives that offer ease of use and reduced morbidity.

Complications and Considerations

While bone grafting procedures are generally successful, they are not without potential complications. Issues such as postoperative infection, sinusitis, graft exposure, edema, and bleeding can occur. To minimize these risks, it is essential to follow the dental provider’s instructions for post-operative care meticulously. Additionally, dental professionals must take precautions during the application of bone graft materials to avoid over-pressurizing the defect site, which can lead to complications such as fat embolization.

Surgical Techniques and Protocols

Sinus Lift

A sinus lift, or sinus augmentation, is performed when the floor of the sinus is too close to the area where dental implants are to be placed. This procedure involves lifting the sinus membrane and adding bone to increase the amount of bone in the upper jaw. The main risk associated with a sinus lift is the potential puncture or tear of the sinus membrane. If this occurs, the surgeon may stitch the tear or place a patch over it, or in more complicated cases, stop the procedure to allow for healing before attempting again.

There are two main techniques for sinus lift: the lateral window technique and the transalveolar osteotome technique. The lateral window technique, introduced by Tatum H in 1975, involves creating an opening in the lateral wall of the sinus and lifting the Schneiderian membrane to place the bone graft and subsequent implants. The transalveolar osteotome technique is less invasive and involves tapping the sinus floor upwards to create space for the graft material.

Ridge Expansion

Ridge expansion, also known as ridge splitting, is a surgical procedure designed to restore the natural form of bone width following a tooth extraction. Before the procedure, patients are required to complete necessary consent forms and will receive IV sedation to ensure they are not awake during the surgery. The dental professional will make an incision into the gums and separate them from the bone using specialized tools. This procedure is typically performed by dental specialists such as periodontists or oral surgeons.

Bone Grafting

During a bone grafting procedure, the surgeon makes an incision in the gum to separate it from the bone where the graft is to be placed. The bone material is then positioned between two sections of bone that need to grow together, and it is secured with either a dissolvable adhesive material or special screws. The incision is subsequently sewn up to begin the healing process. There are three main types of dental bone grafts, each suitable for different circumstances affecting the jaw.

The graft material can be derived from various sources, including autografts (from the patient’s own body), allografts (from a donor), xenografts (from another species), and synthetic variants. The choice of material depends on the specific needs of the patient and the clinical situation.

Two-Stage Technique

The two-stage technique involves performing bone augmentation during an initial surgical procedure and placing the dental implants at a later stage once sufficient bone volume has been established. This staged approach allows for better integration of the graft material and ensures that the bone is adequately prepared to support the dental implants.

Outcomes

Bone grafting has proven to be a highly successful procedure in the context of dental implants, significantly enhancing the implant success rate and patient outcomes. Recent studies have re-examined the success rate of bone grafts specifically for dental implant applications, highlighting their effectiveness. For instance, one study reported a dental implant survival rate of 99.3% and a success rate of 90.7% when using various graft materials over follow-up periods ranging from 1.0 to 5 years.

Different graft materials yield varying outcomes. Autografts, which involve using bone from the patient’s own body, typically offer the highest success rates due to their superior integration and reduced risk of rejection. These grafts are often harvested from the jaw, hard palate, or chin, and are regarded as the gold standard in bone grafting due to their inherent osteogenic, osteoconductive, and osteoinductive properties. However, they do come with risks associated with the donor site.

Allografts, derived from human donors, and xenografts, derived from non-human species such as bovine sources, are also commonly used. Allografts have shown to be effective, though they carry a slightly higher risk of immune response compared to autografts. Xenografts, particularly those made from deproteinized bovine bone like BioOss™, are noted for their long-lasting presence in the recipient site and favorable bone remodeling characteristics.

Artificial and synthetic bone substitutes are increasingly being used due to their customizable properties and ease of availability. These materials can be enhanced with growth factors and other biologically active components to improve their osteoconductive and osteoinductive potentials. Despite their advantages, the cost and the need for further research into their long-term outcomes remain considerations for clinicians.

Complications, although rare, can occur and include postoperative infection, graft exposure, and edema among others. These complications underscore the importance of careful preoperative assessment and precise surgical techniques.

Complications

A dental bone graft is generally considered a safe and effective procedure; however, like any surgical intervention, it carries the risk of potential complications. Postoperative infection is a common concern and necessitates the full course of antibiotics to mitigate this risk. Other complications that may arise include sinusitis, graft exposure, graft loss, edema (swelling), seroma formation (accumulation of fluid), bleeding, and membrane exposure.

During certain procedures, such as ridge expansions and maxillary sinus lifts, additional complications may occur. For instance, severe edema and post-surgical ecchymosis were reported in some cases, although complications like buccal cortical plate complete fractures did not develop. In many instances, a membrane is used to cover the bone graft for additional protection, and the gum tissue is then repositioned and closed with stitches. Despite these precautions, normal side effects such as pain, swelling, and bruising are to be expected and typically subside within a few days.

It is crucial for patients to be aware of these potential complications and to seek prompt medical attention if they experience any unusual or severe symptoms post-surgery.