Dental Bone Substitute: Options and Limitations

By Morey Furman, DDS.

Dental bone loss is a common problem in modern dentistry. There are several causes for this condition. The most common one by far is tooth loss. Accidents, periodontal disease, and ill-fitting dental prosthesis are a few other causes. The bone resorption that occurs is irreversible. Often this situation needs to be corrected for successful dental treatment such as implant placement or ridge augmentation (for proper fitting dentures). Bone grafting is the only solution to reverse alveolar bone loss and is a well-accepted procedure. Research and development in materials, design, and fabrication technologies have expanded over the years to achieve successful and long-lasting dental implants for tooth substitution.

This review will critically present the various dental bone graft and substitute materials that have been used to achieve a successful dental implant. The article also reviews the properties of dental bone grafts and various dental bone substitutes that have been studied or are currently available commercially. Different types of bone substitutes are presented and the limitations of the materials are highlighted.

Using dental bone substitutes has become common for such procedures as dental implants and periodontal bone grafting. As modern bone tissue engineering evolves there is an increasing demand, for effective solutions to address the challenges posed by tooth loss, and associated bone deficiency. This article explores the available options for dental bone substitutes and bone remodeling. By understanding bone graft material and their roles in dental surgery, dental professionals and patients can make informed decisions regarding treatment options.

What Are Dental Bone Substitutes?

Dental bone substitutes are materials used to replace or augment bone tissue that has been lost due to trauma, disease, or surgical procedures. These substitutes are critical in various dental interventions to support implants or other restorations. Common dental procedures that may require bone substitutes include:

Dental Implants: To provide a stable foundation for artificial teeth or dentures. There must be sufficient support. Enough bone must be present to anchor and integrate with the implant.

Ridge Augmentation: This procedure increases the width or height of the jawbone to support dental implants and dentures effectively.

Periodontal Surgery: Bone substitutes are used in grafting procedures to restore bone loss due to periodontal disease.

Types of Dental Bone Substitutes

The main categories of dental bone substitutes include:

• Autografts
• Allografts
• Xenografts
• Synthetic substitutes

Each type has unique properties and applications, which are essential for successful dental outcomes.

What is the Extracellular Bone Matrix (ECM)?

The extracellular bone matrix (ECM) is the non-cellular component of bone tissue, providing structural and functional support. It is composed primarily of:

1. Collagen Fibers: Type I collagen is the primary protein, giving the matrix its tensile strength and flexibility.
2. Minerals: Calcium phosphate (primarily in the form of hydroxyapatite crystals) provides the bone with rigidity and strength.
3. Proteins and Growth Factors: Includes proteins like osteocalcin, osteonectin, and growth factors like bone morphogenetic proteins (BMPs) that regulate bone formation and remodeling.
4. Non-Collagenous Proteins: Proteins like fibronectin and laminin help with cell attachment and signaling.

The ECM acts as a scaffold for bone cells (osteoblasts, osteoclasts, and osteocytes) and plays a crucial role in bone regeneration and healing.

How is ECM Used in Dental Bone Grafting?

ECM is used in dental bone grafting to stimulate bone growth and enhance the integration of graft materials with existing bone. ECM products are typically derived from natural sources, such as:

1. Demineralized Bone Matrix (DBM):
   • This is processed bone tissue where the minerals have been removed, leaving behind an organic matrix rich in growth factors like BMPs.
   • DBM can be used in dental grafting to encourage the patient’s own bone cells to grow and regenerate the bone tissue needed for procedures like dental implants.
2. Synthetic ECM Scaffolds:
   • Artificial scaffolds mimicking the properties of natural ECM are designed using biocompatible materials like hydrogels, ceramics, or polymers. These scaffolds support cell adhesion, proliferation, and differentiation.
   • They are often enhanced with growth factors or stem cells to accelerate bone regeneration.
3. Xenografts or Allografts:
   • ECM materials sourced from animals (xenografts) or human donors (allografts) are sterilized and processed for dental use. These grafts act as a scaffold to guide new bone formation and integrate into the patient’s jawbone.
4. Collagen-Based Matrices:
   • Collagen from the ECM is often used as a carrier for other graft materials or by itself to promote wound healing and tissue regeneration in dental surgeries.

Autografts

What is an Autograft?

An autograft is a bone graft taken from the patient’s own body. The graft material is typically harvested from areas such as the palate, mandible, hip, jaw, or tibia. Autografts are considered the gold standard in bone grafting due to their high success rates and compatibility with the recipient’s body.

How Autografts Work in Bone Regeneration

Autografts work by providing not only a structural scaffold for new bone growth but also living cells and growth factors that promote healing and integration. The natural properties of autografts enable them to support bone regeneration effectively.

Advantages

• High Success Rate: Since the biologic materials for the graft come from the graft recipient, there are no immune or compatibility issues. Autographs represent the highest degree of biological safety. This type of graft has a remarkable track record of success due to their biocompatibility and osteogenic potential.
• No Risk of Disease Transmission: Since the graft comes from the same patient, there is no risk disease transmission.
• Faster Integration with Natural Bone: The most common type of autograft uses cancellous bone which has considerable osteogenic potential. It facilitates the establishment of an osteoinductive environment by encouraging revascularization and incorporation into the recipient site. Integration is quicker than other substitutes, facilitating faster recovery.

Limitations

• Limited Availability: Harvesting bone requires a donor site, which may limit the amount of graft material available.
• Additional Surgery Needed: The procedure necessitates a secondary surgical site for graft harvesting, increasing overall surgical time and complexity. The possibility of increased pain or surgical complications, scaring and higher cost.
• Increased Recovery Time and Discomfort: Patients may experience more discomfort and a longer recovery period due to the additional donor surgical procedure.

Definition of Allografts

Allografts are bone grafts sourced from human donors. They are typically obtained from tissue banks and processed to ensure safety and sterility. Allografts can be an effective alternative to autografts when sufficient bone cannot be harvested from the patient.

How Allografts are Sourced

Allografts are obtained from either a compatible living donor or cadaveric bone source with strict screening processes in place. This minimizes the risk of disease transmission. The most common form of allograft used in dentistry today is the freeze-dried form. The reason for this is most likely convenience, a long shelf life and decreased immunogenicity (due to the freeze-drying process). The two main types of allografts used in dentistry are:

• Demineralized Freeze-Dried Bone Allograft (DFDBA): This type of demineralized bone matrix (DBM) retains growth factors and proteins that promote bone healing.
• Mineralized Freeze-Dried Bone Allograft (FDBA): This type is processed to retain its mineral content, providing structural support (matrix) for osteointegration.

Advantages

• No Need for Donor Surgery: Allografts eliminate the need for a second surgical site, simplifying the procedure for the patient. Less potential complications, less pain, etc.
• Widely Available: Tissue banks provide a large supply of allograft materials, making them easily accessible.
• Successful Integration: Allografts have been shown to integrate well with the recipient’s bone in many cases.

Limitations

• Risk of Disease Transmission: Although rare, there is still a potential risk of disease transmission due to the use of human tissue.
• Slower Healing Compared to Autografts: Allografts may have a slower integration process due to the absence of live cells.
• Possibility of Immune Response or Rejection: There is a risk that the patient’s immune system may respond negatively to the foreign tissue.

Xenografts

What are Xenografts?

Xenografts are bone grafts sourced from genetically unrelated species from the host animals. The most commonly used in dentistry is bovine (cow) or porcine (pig) sources. These materials undergo processing to remove organic components, leaving behind a mineral scaffold that can support bone growth.

How Xenografts Are Processed

Xenografts are treated with a stepwise annealing process followed by a chemical process to produce a porous hydroxyapatite material containing only the inorganic components. The processing involves sterilization and the removal of any cellular material, The resulting porous structure highly resembles that of human bone. It provides good mechanical support and stimulates osteoconduction, to ensure safety and biocompatibility. It also helps minimize the risk of immune reactions.

Advantages

• No Need for a Second Surgical Site: Like allografts, xenografts do not require additional surgery, which can be a significant advantage for patients.
• Abundant Supply: Animal-derived materials are plentiful and can be produced in large quantities. They are readily available commercially.
• Can Serve as a Scaffold for Natural Bone Growth: Xenografts provide a structural framework that encourages the body to regenerate its bone.

Limitations

• Potential for Slower Integration: Due to the fact that xenographs provide only an inorganic matrix, the xenografic integration is slower compared to autografts. (Autografts and allografts also contain an organic substrate to help induce bone growth).
• Ethical and Religious Concerns: Some patients may reject xenografts for ethical or religious reasons, which could limit their use in certain populations.
• Risk of Immune Response or Delayed Healing: Although the risk is lower, there is still a possibility of immune reactions that can affect healing.

Synthetic Bone Substitutes

Overview of Synthetic Materials

Synthetic bone substitutes are man-made materials designed to mimic the natural structure and function of bone. Common examples include calcium phosphate, hydroxyapatite, and bioactive glass. These materials can be tailored for specific clinical applications.

Types of Synthetic Bone Substitutes

• Ceramic-based Substitutes: Often made from calcium phosphate, these materials are biocompatible and promote bone regeneration.
• Polymer-based Substitutes: These materials can provide flexibility and are often used in conjunction with other graft materials. They are customizable in shape, are low in immunogenicity and can control other characteristics. Properties such as resorbability, porosity and physiochemical structure are controllable.

Advantages

• Completely Sterile: Synthetic substitutes are manufactured under sterile conditions, significantly reducing the risk of disease transmission.
• Consistent and Predictable Quality: The manufacturing process ensures that synthetic materials meet specific quality standards.
• Customizable Shapes and Sizes: Synthetic substitutes can be tailored to fit the specific needs of the procedure, providing versatility.

Limitations

• Potential for Slower Bone Regeneration: Synthetic materials may not promote bone growth as effectively as natural grafts.
• Not as Biocompatible as Natural Bone: Some synthetic substitutes may lack the biological properties that enhance healing.
• Risk of Resorption Before Complete Healing: Certain materials can be resorbed by the body before sufficient new bone has formed causing the graft to fail. Concerns relating to the alteration of local pH exist.

Growth Factors and Bone Regeneration

What are Growth Factors?

Growth factors are naturally occurring proteins that play a vital role in regulating cellular processes, including bone regeneration. They can enhance the performance of bone substitutes and improve healing outcomes.

Common Growth Factors Used

• Platelet-Rich Plasma (PRP): PRP is derived from the patient’s blood and contains a high concentration of growth factors and cytokines, which can help speed up healing and reduce pain.
• Bone Morphogenetic Proteins (BMPs): These proteins stimulate the formation of new bone and are often used in conjunction with graft materials.

Advantages

• Faster Bone Regeneration: The use of growth factors can accelerate the healing process and improve the osseous integration.
• Improved Integration: Growth factors enhance the body’s natural healing response, leading to better outcomes and faster healing with less complications.

Limitations

• Cost of Treatment: The use of growth factors can increase the overall cost of dental procedures.
• Limited Data on Long-Term Outcomes: While growth factors show promise, the research is limited on their long-term efficacy and safety.

General Limitations of Dental Bone Substitutes

Factors Affecting Success

The success of dental bone substitutes can be influenced by several factors, including:

• Age and Health of the Patient: The health of the patient plays a significant role in the success of treatment. Conditions such as diabetes, osteoporosis and other systemic illnesses can affect healing time and cause other complications.
• Site Conditions: Local factors can affect graft integration and treatment success. Situations such as poor local blood supply or infection are just two local factors that can that affect treatment outcome.
• Size and Complexity of the Bone Defect: The larger the site is or more complex the defect the greater the challenges are for successful regeneration.

Are There Alternatives to Dental Bone Grafts?

Yes, there are alternatives to dental bone grafts depending on the patient’s specific needs, overall oral health, bone volume, and the severity of the issue. Here are some common options:

1. Ridge Preservation

After a tooth extraction, a bone preservation technique can be used to minimize bone loss. This involves placing a special material into the tooth socket to encourage natural new bone formation without needing a full graft.

2. Zygomatic Implants

These implants are anchored in the zygomatic (cheek) bone rather than the jawbone, bypassing the need for a bone graft. They are often used in cases of severe lost bone in the upper jaw.

3. Sinus Lift Alternatives

For patients with bone loss in the upper jaw near the sinuses, short dental implants or special techniques like subperiosteal implants and other sinus augmentation procedures may be used instead of a sinus lift with bone grafting.

4. Bone Regeneration Techniques

Non-invasive options like guided tissue regeneration (GTR) use special membranes to encourage the body’s natural bone regeneration without additional grafting material.

5. Dental Bridges or Dentures

If implants are not an option or a patient prefers to avoid surgical procedures, a dental bridge or a partial denture can replace missing teeth without addressing bone loss directly.

6. Stem Cell Therapy

Emerging technologies in regenerative medicine involve stem cell therapy to promote natural bone regrowth. Although still developing, this option may provide a non-graft alternative in the future.

7. Orthodontic Solutions

In certain cases, orthodontic treatment can help reposition teeth to close gaps, reducing the need for implants or bone grafting.

Common Challenges Faced by Dental Professionals

• Slow Healing Process: Many bone substitutes can require extended healing periods. It takes time for osseous intergration and bone formation. Autografts have the fewest complications and heal the fastest. Allografts heal slower. The DFDBA heals faster and with fewer complications than FDBA. The proteins and growth factors preserved in DFDBA support bone growth and faster healing, which can reduce potential complications and lead to more predictable treatment outcomes.Xenografts also heal relatively slowly, putting them in the third position following FDBA. Even though the healing is slower, xenograft material is readily available and one of the preferred graft materials used.
• Possibility of Graft Failure or Resorption: There is always a risk that the graft may not integrate properly or be resorbed too quickly. The surgical site needs to be carefully monitored and handled with care. Using the best possible graft material for the site conditions and patient health and comfort, will always improve grafting success.
• Additional Surgeries May Still Be Required: Especially in difficult or complex cases, multiple surgeries may be necessary. Situations such as graft resorption or infection can cause complications for the initial grafts to heal properly or at all. When complications develop there is often need for additional surgeries to correct the treatment provided.

Innovations and Future Trends in Dental Bone Substitutes

Advances in Tissue Engineering

With the advancement of the biological sciences over the past couple of decades, tissue engineering is revolutionizing the field of dental bone substitutes. Techniques that combine a matrix (inorganic scaffolds) with growth factors and stem cells are being developed to create more effective solutions for bone regeneration.

The Role of 3D Printing

3D printing technology is a valuable tool in dentistry, allowing for the creation of custom-shaped bone grafts to fit the clinical situation. This enhances the precision, effectiveness, and ease of surgical grafting procedures. 

New Materials and Technologies

Research is ongoing into new materials and technologies aimed at improving the performance of bone substitutes. Innovations include bio-active glasses and novel polymers that may offer better integration and regeneration potential. There is a recent trend for the incorporation of osteoinductive growth factors with a structural scaffold to increase the material’s bone regenerative potential and inhibit undesirable inflammatory responses.

Potential for Stem Cell Therapy

Stem cell therapy holds promise for the future of dental bone regeneration. By harnessing the body’s own regenerative capabilities. This approach leads to more effective treatments with fewer complications with bone replacement.

Transform Your Dental Practice with Stomadent Dental Lab

As the field of dental bone substitutes continues to evolve, dental practices must stay informed about the latest innovations and materials. Collaborating with a reputable dental lab, such as Stomadent Dental Lab, can provide access to cutting-edge solutions that enhance patient outcomes and streamline treatment processes.

If you’re looking to improve your practice and offer the best to your patients, consider integrating advanced bone substitute options into your procedures. Contact Stomadent Dental Lab today to learn more about how we can support your practice and help you stay at the forefront of dental care.

 This overview of dental bone substitutes highlights the various options available, their advantages, and their limitations. By understanding these factors, dental professionals can better assess the needs of their patients and select the most appropriate materials for each unique situation. The future of dental bone substitutes looks promising.