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Bone Grafting Materials: What the Experts Think

Neil Park, DMD, Director of Clinical Affairs

article by Neil Park, DMD, Director of Clinical Affairs

Bone augmentation prior to or during implant placement can improve the final esthetics as well as the functional aspect of the patient’s restoration. However, there is an assortment of materials and techniques for the practitioner to choose from. We had the good fortune recently to convene a meeting of experts to discuss the best options for specific indications.

“Almost 100 percent of my implant cases require bone grafting,” says Dr. Carl Misch, distinguished implantologist, textbook author and founder of the Misch International Implant Institute. “Because bone is lost so rapidly after a tooth extraction, it is a very common requirement to return the ridge to something ideal for either esthetics or functional implant position.”

“An average of one out of three implants needs some sort of grafting,” says Dr. Jack Hahn, implantology pioneer and developer of the original tapered implant. “Most of the time, it’s in the anterior region because you’re trying to support the soft tissue, which affects the esthetics. In the posterior, we’re often filling molar sockets or placing the graft around an implant in a molar area where there is a wide opening.”

“Molars seem to have the greatest variation in the need for grafting,” says Dr. Paresh Patel, prominent implantologist and respected educator. “In healed sites, 30 percent of my cases need hard-tissue grafting to create an acceptable site.”

The goal of bone grafting is to help the patient grow new bone by replacing the graft through a process of self-mediated resorption and regeneration. Implantologists encounter various scenarios for this remodeling process, including ridge preservation, sinus augmentation, lateral ridge augmentation, and immediate implant placement. Each situation calls for individualized considerations in material selection, and each expert has a preferred approach for choosing regenerative materials.

Material Selection

Ridge Preservation

Allograft materials have been widely used in dentistry and are preferred by Dr. Misch for socket grafting. “A cadaver, mineralized bone source that is cortical in nature is the most common material that will fill and maintain the space until the graft is replaced with bone,” he says.

"In most of my grafting cases, I use a cortico/cancellous mix."

Dr. Patel agrees. “For socket preservation, the most accepted material is the allograft,” he says. “In most of my grafting cases, I use a cortico/cancellous mix (Figs. 1a–1f).”

Dr. Hahn also prefers using a mineralized cortico/cancellous allograft material. “It shares many of the components of the patient’s own tissue, and the body remodels it like natural bone,” he says.

Dr. Misch emphasizes that he currently does not use demineralized bone within the allograft. “There was a time when I was mixing the two together,” he says. “The theory behind demineralized trabecular bone is that it contains a very small amount of bone morphogenetic protein (BMP). Dr. Marshall Urist found that demineralized bone had some BMP; and BMP could alter a cell that was going to become a fibrocyte and make fibrous tissue, and change it to a cell that will make bone — an osteoblast.1-3 Because of his work, it became very popular to use demineralized bone because it had a little BMP in it. In my studies, the amount of BMP is so small, it really couldn’t be quantified how much it was contributing to the overall remodeling process in the grafted site.

“What’s more important is that the bone graft material maintains the space,” Dr. Misch continues. “Demineralized bone doesn’t keep the space long enough to be predictably replaced by bone. So that’s why I always use mineralized bone.”

Over the top of the grafted socket, Dr. Misch sutures a collagen membrane to the surrounding tissue. Dr. Hahn also covers the area with a membrane. “I prefer membranes that resorb in anywhere from six weeks to three months because I don’t like to do a second surgery to recover the membrane,” says Dr. Hahn.

However, depending on the size of the defect, in some cases Dr. Hahn covers the allograft with a synthetic bone putty, which acts as a membrane that can protect the graft, as well as support and enhance the soft tissue.

For a three- or four-wall bony defect, like a socket, Dr. Patel typically enlists the help of a collagen membrane that resorbs in six months or less.

Sinus Graft

In sinus grafting, Dr. Patel again uses allograft material. “I prefer to use the blend,” he says. “With cortico/cancellous, some bone is more dense, which will take longer to turn over, and some of the bone is cancellous, which will turn over faster.” For example, Dr. Patel recently used Newport Biologics Mineralized Cortico/Cancellous Allograft Blend for a lateral window sinus lift (Figs. 2a–2e).

Dr. Misch uses the same allograft material for a sinus graft as he uses for a socket graft. “Mineralized cortical bone, larger particle sizes mixed with smaller particle sizes,” he says. Often he puts a membrane, lasting at least six weeks, on the lateral access wall.

For sinus grafting, specifically for grafting the lateral window, Dr. Hahn says, “I prefer to fill with cortico/cancellous bone, then cover with a membrane that lasts anywhere from three to six months.” As such, Newport Biologics Resorbable Collagen Membrane 3–4 or Resorbable Collagen Membrane 4–6 may be utilized.

For a sinus bump, Dr. Hahn prefers to use an alloplast putty. “It’s more convenient to use the putty than the granules,” he says. “I have done hundreds without any complications.”

Lateral Augmentation

For lateral augmentation, Dr. Misch uses a layered approach. “I harvest autologous bone, usually cortical bone from some place, whether it’s from the tuberosity, the ramus, or below the roots of some teeth,” he says. “I take a little cortical bone and I put that on the bottom layer. For the rest of the graft, I use the mineralized cortical bone, and that forms the majority of the material. And then on top of that, I put a collagen membrane that will last longer than six weeks.”

Dr. Patel often utilizes autologous bone harvesting and a tent screw. “If we do a tent screw, we want to harvest some of the patient’s autologous bone, use that right up against the bone at the recipient site, fill in the rest of the space with a mineralized cortico/cancellous blend, and then apply a collagen membrane over that,” he says. Dr. Patel uses a six-month resorbable membrane material for these procedures.

For a lateral augmentation, Dr. Hahn uses either a combination of cortico/cancellous allograft granules or an alloplast putty. Newport Biologics Bone Graft Putty Mineral-Collagen Composite is a moldable putty upon hydration and is fully resorbed during the natural process of bone formation and remodeling.

Graft for Immediate Implant Placement

Material selection is case-specific, and Dr. Hahn’s choice of grafting materials for extraction with immediate implant placement depends on the size of the gap between the socket walls and the implant body. He uses an allograft for larger defects and alloplast putty to fill small gaps. “When I have to take out a tooth and there is a large facial defect, I will put the implant in, make sure it is stable, graft it with bone particulate, cover it with the synthetic putty, and then suture,” he says.

Dr. Patel typically uses a mineralized cortico/cancellous blend (Figs. 3a–3g). However, he uses an alloplast in certain cases. For example, in tight spaces, he opts to place alloplast putty (Newport Biologics Bone Graft Putty Mineral-Collagen Composite) straight down on the buccal wall of bone and across to the threads on the facial of the implant. “It’s a synthetic, but it certainly offers ease of use,” he says. “The alloplast can take longer to turn over than an allograft, but we’re just trying to give the body something to use as a scaffold to turn into the patient’s own bone.”

For immediate implant placement, Dr. Misch uses the same allograft material as he uses for both a socket graft and sinus graft procedure. “The only time I use the bovine bone is if I want the graft to maintain space for more than three to four months,” he says. “On the other hand, if I want to put a graft in and I want it to form bone as fast as possible, then I’ll use the human bone because it remodels faster than bovine bone. So the choice in material could be related to how long I want it to last.”

Drs. Jack Hahn, Paresh Patel, Neil Park, Carl Misch and Vivian Roknian at the 2016 annual ICOI Summer Implant Symposium in San Diego.

Conclusion

Implantologists can choose from several different materials when augmenting bone for implant placement. While allograft material tends to be chosen the majority of the time for each of the above indications, the proper selection of regenerative materials can be determined by considering the advantages each material affords in any given case.

References

  1. Urist MR, Strates BS. Bone morphogenetic protein. J Dent Res. 1971 Nov-Dec;50(6):1392-406.
  2. Urist MR. Mesenchymal cell reactions to inductive substrates for new bone formation. In Dunphy JE, Van Winkle W Jr., editors: Repair and regeneration: the scientific basis for surgical practice. New York: McGraw-Hill; 1969.
  3. Misch CE. Contemporary implant dentistry. 3rd ed. St. Louis: Mosby; 2007.
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