Improving osseous graft handling by incorporation of PRP to create “gummy bone”

Editor’s intro: “Gummy bone” — the product of incorporation autologous blood concentrates such as PRP into a particulate graft material — improves handling characteristics and can be utilized in a variety of clinical graft situations.

Drs. Arun K. Garg, Gregori M. Kurtzman, Renato Rossi Jr., and Maria del Pilar Rios discuss the benefits of using patient-derived autogenous blood concentrates mixed with particulate graft material

Introduction

Clinically, there are situations where osseous grafting needs to be performed. This can vary from socket preservation following extraction, repair of bone loss at the furcation, filling voids between the socket walls and implant when immediate implants are planned, and treatment of exposed implant threads to sinus augmentation. These are managed by use of osseous particles, which can be allografts, autografts, xenografts, or even synthetic materials.

The typical problem with particles is the potential for dispersement during the initial healing period. Although they may be rehydrated or wetted with various liquids such as saline, water, or anesthetic, these liquids do not hold the particles together and allow them to spread in the area during healing. This will lead to less volume of healed graft at the site desired and may compromise the intended results. Utilization of patient-derived autogenous blood concentrates mixed with the particulate graft material improves graft handling during placement as well as maintenance at the intended site, eliminating dispersion potential. Autologous blood concentrates are defined as the concentrated portion of the patient’s blood following centrifuging that contains growth factors, platelets, white blood cells (WBCs), and fibrin but does not contain the red blood cell (RBC) portion of the blood.

Benefits of using autogenous blood concentrates with osseous graft materials

In the 1980s, several reports identified the pivotal role oxygen plays in wound healing.1-5 These studies were the first to recognize that growth factors promote healing related to the macrophage response to oxygen gradients, which secreted those wound-healing growth factors. Platelet-derived wound-healing factor (PDWHF) was first introduced clinically6 and continued on to platelet-rich plasma (PRP) utilized for over 2 decades to initiate wound healing. Thrombin-released platelets produce angiogenesis and collagen synthesis with fibrin eliciting a cellular exudate, followed by angiogenesis. In the early 1990s, Marx and Garg began work on using patient-derived blood as a fibrin source for use with osseous grafts to improve product handling. This fibrin adhesive was first published in 1994.7

Platelets secrete growth factors (PDGF-AA, PDGF-BB, and PDGF-AB) that stimulate mesenchymal stem cells to replicate, osteoblasts to replicate and produce osteoid, endothelial cells to replicate secreting basal lamina for new blood vessels, and fibroblasts to replicate producing collagen. Additionally, transforming growth factors (TGFß1 and TGFß2) and bone morphogenic protein (BMP) are present that stimulate matrix production and guide cell differentiation into bone. Other factors present in the autologous blood concentrates include vascular endothelial growth factor (VEGF), which supports new blood vessel development, and epithelial growth factor (EGF), which stimulates migration of the surrounding soft tissue to cover the area and form a basement membrane.

Incorporation of autologous blood concentrates such as PRP into a particulate graft material provides growth factors to accelerate healing of the graft, stimulating the host cells adjacent to the graft to convert into native bone. More rapid closure of the soft tissue using the patient’s own factors as that stimulating mechanism can be expected. The additional benefit is a gelatinous mass, termed “gummy bone,” that has improved handling without the dispersion issues found with graft particles mixed with saline or even allowed to absorb blood at the site (Figure 1). Gummy bone has a flexible putty-like consistency that can be cut to desired dimensions prior to placement and utilized in a variety of clinical graft situations, which include the following:

  • socket grafting (Figure 2)
  • filling voids around immediate implant placement (Figure 3)
  • lateral sinus augmentation (Figure 4)
  • crestal sinus augmentation (Figure 5)
  • lateral ridge expansion (Figure 6)
  • dehiscence repair at implant placement (Figure 7)
  • furcation repair (Figure 8)
  • grafting fill of defects on the lateral aspect of the ridge (Figure 9)
Figure 1: The gummy bone has improved handling charac-teristics for placement in sites, eliminating the potential for particle dispersement during healing
Figure 2: Following extraction, gummy bone is placed into the socket for preservation of the site
Figure 3: Voids between the implant being placed and the extraction socket walls are filled with gummy bone prior to site closure
Figure 4: Gummy bone being placed into a lateral window sinus augmentation, allowing better placement against the medial, distal, and mesial walls of the elevated sinus
Figure 5: Gummy bone being introduced into the osteotomy where a crestal sinus elevation has been performed to increase the crestal height prior to implant insertion
Figure 6: Gummy bone being placed between the facial aspect of the ridge and the bone plate placed to widen the ridge to allow implant placement after healing
Figure 7: Placement of gummy bone over exposed implant threads at implant placement that will allow the osseous graft to remain where needed as the bone heals and prevent dispersement found when particulate graft is used alone
Figure 8: Placement of gummy bone into a furcation defect, allowing the graft to remain where placed and avoid disperse-ment potential typically observed with particulates rehydrated with saline
Figure 9: Placement of gummy bone to fill a defect in the anterior mandible apical to the existing teeth

Fabrication of “gummy bone”

At the initiation of the surgical treatment, blood is drawn from the patient into red-top tubes. The red-top tubes are glass walled and contain no anticoagulant. These are then immediately centrifuged at 3,200 rpm for 3 minutes (about 600 gf) to create separation of the layers of the patient’s blood (Figure 10). Once centrifuging is complete, distinct layers present in the tube (Figure 11). For the purposes of creating gummy bone, the yellow layer, the plasma that is high in fibrin and platelets, will be used.

The osseous graft particles that will be used are dispensed into a sterile dish (Figure 12). The plasma liquid is withdrawn from the tube with a syringe and needle (Figure 13) and then dispensed into the dish containing the osseous graft material (Figure 14). This hydrates the dry graft particles and is allowed to sit for 10-12 minutes to coalesce into a gelatinous mass (Figure 15). Following the coalescence period, the gummy bone is formed and is ready for use (Figure 16). This does not need to be immediately used during the surgery and can sit in the dish until graft placement in the treatment process is ready. The gummy bone can be used as a single mass (Figure 17) when placing in large voids such as sinus augmentation or cut with scissors into smaller pieces (Figure 18) that can be incrementally placed into the surgical site. These pieces will adhere to each other when they are placed into contact with each other or the surrounding tissues.

Figure 10: Following phlebotomy, the patient’s blood is centrifuged at 3,200 rpm for 3 minutes (about 600 x gf)
Figure 11: Following centrifugation, the blood separates into several layers as outlined in the image above
Figure 12: Allograft (cortical, cancellous, or a mixture of the two) are dispensed from the bottle into a sterile dish
Figure 13: The plasma (yellow liquid) is drawn out of the centrifuged tube with a syringe
Figure 14: The plasma is placed into the sterile dish containing the allograft particles
Figure 15: The plasma wets and rehydrates the allograft particles and is allowed to sit for 10-12 minutes before use
Figure 16: After 10-12 minutes, the fibrin within the plasma that had been mixed with the allograft particles forms a gelatinous mass referred to as “gummy bone”
Figure 17: Once the gummy bone is created, a gelatinous mass is formed that is easily carried to the desired site
Figure 18: The gummy bone can be cut into appropriately sized pieces depending on the clinical need

Conclusion

As discussed, one of the main challenges to osseous grafting is handling of the graft materials during both placement and the initial healing period. Particle dispersement is not uncommon with particulate materials as when wetted by non-hematological liquids; this limits site blood from infusing into the graft placed initially, allowing dispersement to occur. Placing the dry particles into the site to be grafted, allowing blood from the surrounding tissues to wet it, also limits holding the mass together. There may be limited bleeding from the bone’s surface and not penetrate throughout the graft placed from bleeding at the soft tissue.

Fibrin from the autogenous blood concentrate has more favorable characteristics acting as “tissue glue” to hold the particulate graft into a pliable mass. This pliable material handles better, allowing easier shaping for the defect being treated with potential to increase width when needed that can not be easily accomplished with particulate bone when autogenous blood concentrates are not added. The added benefit of the platelets and associated growth factors stimulate angiogenesis, thus using the patient’s own systemic factors to aid in graft coalescence, organization, and maturation. Those practitioners, who are utilizing particulate graft materials in their treatment modalities, should consider incorporating autogenous blood concentrates like PRP to improve graft handling, eliminate particle dispersement during healing, and stimulate regeneration via the growth factors that are now incorporated within the placed graft material.

Besides the use of gummy bone, many other innovations have been written about in Implant Practice US. Read “Autologous bone grafting using extracted teeth” by Dr. Armin Nedjat here.

Arun K. Garg, DMD, is an internationally recognized dental educator and surgeon who, for more than 20 years, served as a full-time professor of surgery in the department of Oral and Maxillofacial Surgery and as director of residency training at The University of Miami Leonard M. Miller School of Medicine. He is considered one of the world’s preeminent authorities on bone biology, bone harvesting, and bone grafting for dental implant surgery. He also is a well-known lecturer and has authored nine published textbooks and a dental implant marketing kit, which has been translated into multiple languages and distributed worldwide. Dr. Garg can be reached at arun.implantseminars@gmail.com.

Gregori M. Kurtzman, DDS, MAGD, FPFA, FACD, FADI, DICOI, DADIA, is in private general dental practice in Silver Spring, Maryland, was a former Assistant Clinical Professor at University of Maryland in the Department of Restorative Dentistry and Endodontics, and a former AAID Implant Maxi-Course assistant program director at Howard University College of Dentistry. He has lectured internationally on the topics of restorative dentistry, endodontics and implant surgery, and prosthetics, removable and fixed prosthetics, and periodontics. Dr. Kurtzman has over 670 published articles globally, several ebooks, and textbook chapters. He has earned a Fellowship in the AGD, American College of Dentists (ACD), International Congress of Oral Implantology (ICOI), Pierre Fauchard, ADI, Mastership in the AGD and ICOI, and Diplomate status in the ICOI, American Dental Implant Association (ADIA), and International Dental Implant Association (IDIA). He is a consultant and evaluator for multiple dental companies. Dr. Kurtzman has been honored to be included in the top “Leaders in Continuing Education” by Dentistry Today, published annually since 2006, and was featured on the June 2012 cover. Dr. Kurtman can be reached at dr_kurtzman@maryland-implants.com.

Renato Rossi Jr., DMD, MSc, PhD, graduated from University of São Paulo – USP – Brazil in 1977 and Oral and Maxillofacial Surgeon and Implantology (USP University Hospital and Hospital Hermanos Ameijeiras Cuba). He obtained his MS and PhD in Pathology and Maxillofacial Surgery (USP – Brazil) and Postdoctoral Degree at the University of Havana, Cuba. He is currently dean of the School of Dentistry – USCS (Municipal University of Sao Caetano do Sul – Brazil), Director of Residency Training at the USCS University and UNIB University, and coordinator of the Laboratory of Research in Biomaterials – USCS University. He is the author of several books and research articles. In addition, Dr. Rossi Jr. is a scientific consultant for several biomaterials companies and lecturer regarding OMF, oral surgery, implantology, oral pathology, and autologous blood concentrates.

Maria del Pilar Ríos Calvo, DDS, Esp. CAGS, MScD, PhD, graduated from Venezuela Central University UCV in 1990, specializing in CAGS. She earned an MS in Prosthodontics at Boston University in 1994 and a PhD at Santa Maria University, Venezuela in 2017. Dr. Pilar is currently the Chairwoman of the Master of Science in the dental implants program and an associate professor at Santa Maria University in Venezuela. She is also a full-time faculty at the Dr. Garg Implant Foundation in Santo Domingo, Dominican Republic in addition to being the President of the Venezuelan Branch of the International Dental Implant Association, IDIA, former Dean and Health Vice Chancellor at Santa Maria University in Venezuela, as well as President of the Venezuelan Prosthetic Society, Secretary of the Venezuelan Occlusal Society, and editor of the Journal of Implant Dentistry in the United States. Dr. del Pilar Ríos Calvo is author of several articles published in scientific journals an active member various scientific societies, and academies. Furthermore, she has been awarded for several research projects.

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