Discussion Topic: Cortical vs Cancellous Graft Material

There are so many graft material options.  Can anyone shed some light on the key differences between cortical and cancellous bone graft materials?  Are they both osteoinductive and if so, to what extent?  What is the difference between mineralized and demineralized cortical particulate allograft materials and when would you use either?  What is the best material or combination of materials for grafting into sockets for socket/site preservation cases?

28 thoughts on “Discussion Topic: Cortical vs Cancellous Graft Material

  1. I’m no expert but this is what works best for me, demineralized cortico-cancellous bone, Mineross or Allosorb are two great brands. brands. Here’s a simple rationale mineralized, cortical takes a long time to resorb, demineralized cancellous resorbs too fast. The combo is just right! (Sounds like Goldlocks!) I let it heal 14-16weeks. I’ve tried them all autologous, allograft and xenograft. But for the sockett application this works well. Two key point good buccal plate and primary closure, collaplug or membrane coverage for good soft tissue preservation. Bio-coll works well but I use Allosorb. Enjoy, now I know the smarter guys will post next!

    • There’s a lot of choices for bone grafting materials on the market. Understanding that the maxilla is mostly constructed of cancellous bone, where as the mandible mostly consist of cortical bone. Cortical bone is used for space maintenance and stability, while cancellous is used for faster remodeling. My company carries multiple types of combination allografts, which are used for socket preservations, ridge augmentations, and sinus lifts. Its important to find a product that gives you great results that you can rely on time after time. Most of my surgeons prefer the combination allograft already premixed because they get the best of both worlds. If you have anymore questions concerning bone grafting please give me a shout @ 912-531-8095

  2. Bone tissue is a matrix- like 
    structure, primarily composed of a protein called collagen. 
    It is strengthened by hydroxyapatite, deposits of calcium and phosphate salts. 
    4 types of bone cells are located within and around this matrix. Together, this 4 types of cells are responsabile for building the bone matrix , maintaining it and remodeling the bone as needed. 
    The 4 types of bone cells are:
    – Osteoblasts, which produce the bone matrix.
    – Osteocytes, mature osteoblastes that maintain the bone.
    – Osteoclasts, which break down and remove bone tissue
    – Bone lining cells, which cover bone surfaces.
    There are 3 ways that a bone graft can help repair a defect:
    -Osteogenesis, the formation of new bone by the cells contained within the graft.
    – Osteoinduction, a chemical process in which the molecules contained within the graft ( bone morphologic proteind BMP) convert the patient’s cells into cells capable of forming bone
    -Osteoconduction, a physical effect whereby the graft matrix configures a scaffold on which cells in the recipient, form new bone. 
    Autograft : bone patient’s own body
    Allograft: bone from a human cadaver. Mineralised or Demineralised ( bone that has had Its calcium removed ).
    BMP are strong inducers of bone growth ( osteoinductive).
    Xenograft: bone from animals ( bovine or equine)
    Alloplast: synthetic bone made from calcium phosphate or cacium sulfate or hydroxyapatite, or ceramic bears

  3. The simple answer to your question is; you have the option of using the patients bone or the bone of another human or animal. Grafting purist believe that autogenous bone is the only way to go. Cortical autogenous has a more dense matrix, with less water and subsequently less viable cells to allow for induction. Cancellous bone on the other hand has more water and more cells that have the potential to allow for actual bone growth. There is some argument as to wether the cells remain viable, once transplanted from harvest to graft site, but there is little science to suggest that there a better material. The demineralization process was thought for the longest time, to be what made demineralized bone work the way it does, but as you have probably noticed, this process is growing out of favor and a lot of doctors suggest mineralized bone hangs around a bit longer. Your question inquired about socket preservation, I do believe, so with regards to that, I encourage taking greater time to consider your graft bed and how you choose to contain whatever material you may choose. This is absolutely the most important facet of socket preservation grafting. There are some strong studies that prove, if the graft site is prepared appropriately and ingrowth of epithelium is prevented, some sites need no material at all. This is not to say you must have primary closure. If you are proficient at harvesting bone, the morbidity is negligible and it is very cost effective. If you are asking the question, then I am assuming you are new to this part of dentistry. Several surgeons in my town use only mineralized bone and get great results. Take a good guided tissue regeneration course. Socket preservation grafting is actually quite enjoyable and very predictable. Once you become more comfortable, you will find that you can save the patient time and money, by placing implants in the extraction site and apply the same techniques, with excellent results. Find a good resorbable membrane that works well in your hands and you will be amazed at how simple this stuff is. Bvinci

  4. i don’t think your initial question was ever answered fully, so i’ll make some brief comments here
    1. cortical vs. cancellous- cortical bone is generally more dense and resorbs more slowly than cancellous bone, which is less dense and contains more cellular and protein components. some evidence exists that cortical bone may be more advantageous for socket grafting as it resorbs more slowly, and as long as it is present soft tissue is less likely to envaginate downward.
    2. are they both osteoinductive- cortical bone is much less likely to have osteoinductive potential as it contained less protein, and bone morphogenic proteins (bmps) are largely responsible for inductivity. having said that, the concept of inductiveness has much more to do with processing than with the original source of the bone. for instance, if they’ve both been cooked to produce anorganic bone matrix, the proteins are incinerated and all that is left is mineral, so no osteoinductiveness exists, only osteoconductiviy.
    3.mineralized vs. demineralized- now we are talking the potential for osteoinductiveness. demineralized means mineral content has been removed, leaving protein behind, so these can be inductive. mineralized means ha content is still there, proteins are removed, and these are largely conductive only
    5. best material- is no such animal. most processed bone grafting materials work given enough time to be resorbed and turned into bone. in theory, the “best” would be a combination of mineralized and demineralized material. the mineralized would resorb more slowly and maintain the space, while the demineralized would potenially provide inductivity. so mixtures or combination products may have an advantage.

    gary

  5. I have bone done many types of socket and ridge preservation osseous grafting procedures for more than 15 years. I like the explanations of E. Wade, Baker K Vinci and Gary Henkel . They are thoughtful and well done. While I tend to prefer mineralized
    bone as I believe it is more stable and provides an excellent scaffold for new bone to grow through and mature. I always wait 16 weeks for my grafts to mature unless they are larger grafts or Sinus lifts in which I wait 6 months. My only addition to the previous information is that I believe that periodontists prefer demineralized bone when doing any bone grafting or regenerative procedure around existing teeth. The reason for this is that the protein left behind in the demineralized bone has inductive potential for regaining periodontal ligament. For this reason and only this reason would I use demineralized bone perhaps in concert with Emdogain.

    Good Luck,

    David

    • I agree that Emdogain is an excellent product to use when trying the regenerate periodontal attachment. And yes it is key to prevent epithelial ingrowth and allow bone to develop. Great discussion.

  6. I’m embarrassed to say I was not aware of the inductive capacity of any allograft. If that is the case then we should be using demineralized bone in all socket preservation grafts, since they all tend to be next to an adjacent tooth. Bvinci

  7. DrQ….you definitely have too much spare time on your hands. Have you ever thought of getting a job writing for SNL…or possibly Steven Colbert of Jon Stewart??

  8. Baker,

    The regenerative potential of demin allograft as its being discussed here is related to periodontal defects, not extraction sites.

    There was a study published recently by Mellonig using Puros mineralized allograft in periodontal defects that had human histology and showed regeneration in a limited # of cases. However it’s important to note that Puros is not your typical FDBA, because of the “Tutoplast” that they use, and it’s never freeze dried.

    There is a paper published by Wood and Mealey that showed DFDBA yielded more vital bone then FDBA in single rooted extraction sites when re-entry with bone trephine cores were used to give the histomorphometric analysis.

    There is a new material on the market by Osteogenics, Encore, which combines both DFDBA and FDBA into a single vial.

    In the end, everyone should read the literature, and make a decision for what is best for their patients, in their hands. It is likely that any of the allografts will give a good result given good technique and enough time.

    In our clinic we have seen that sites grafted with DFDBA sometimes do not look as great (due to lack of mineral content) on either the CBCT or PAs at the time of placement, however the grafts are rock solid surgically.

    TB

  9. The only osteoinductive and osteoconductive bone graft is Autogenous bone graft & all other types of bone replacing materials are osteoconductive only. To preserve the socket volume and reduce bone resorption after extraction there is no evidence base on certain method, but I prefer to fill the socket with artificial bone graft and covered with collagen membrane.

  10. There are many differences between cortical and cancellous bone while living but the only difference when dead is the mineral content. Cortical bone in about 95% mineralized tissue and cancellous bone is between 35 and 45% mineralized tissue. Neither cortical or cancellous bone allografts are osteoinductive or osteogenic and these terms are rarely understood. An osteoinductive substance is a material that has the ability to grow bone outside of bone. An osteogenic substance is a material that modifies the physiology of the osteoblasts and stimulates the osteoblast to produce bone at a faster rate than bone would grow if the substance was not present. But don’t believe me on these terms contact the FDA for clarification. The proteins in allografts produce inflammation not bone growth. You are putting proteins from another person into your patient without any effort to match the proteins and you think there will not be an inflammatory response? I have never seen a paper or a patient where an allograft is resorbed. Most sites grafted with allografts are hard and highly mineralized but you sacrifice bone vitality and the ability to respond to changing loads for mineral density. Sorry to gore some sacred cows. Greg Steiner Steiner Laboratories

    • Greg,

      Part of your statement is good fact, in that your definitions of osteoinductive and osteoconductive materials is solid. However you’re incorrect in stating that no allograft is osteoinductive. In fact, most major manufacturers (LifeNet and Osteogenics come to mind) test the inductive potential of their DFDBA lots. Most often the lots are tests by in vitro BMP-2 assays before sterilization, and after sterilization tested for osteoinductive potential following the gold standard, an In Vivo Osteoinduction Assay in the Athymic Rat.

      For those of you who don’t know what this entails, the bone is placed into the hind legs (biceps femoris) into a muscle/skin pouch and then sutured closed. After a period of time the animal is sacrificed. Tissues are fixed and stained. Slides are reviewed under a microscope and interpreted by a pathologist; the histopathology is semi-quantitative, using a scoring system. The pathologist notes “Observed Elements of New Bone Formation”, which includes the presence of chondroblasts/chondrocytes, osteoblasts/osteocytes, cartilage/osteoid, new bone, bone marrow, and original allograft. A grade of 0 – 4 is given, where 0 represents no evidence of new bone formation, and grades 1 – 4 represent evidence of new bone formation in varying percentages of the cross-section of the field reviewed.

      Most companies fail lots that grade 0. Or so we hope. The real dilemma (as described by Zvi Schwartz recently in a lecture I attended) is the use of bisphosphonates. Most donors are elderly, most elderly people take these drugs, and the FDBAllografts commonly used likely COULD contain these drugs after processing. Zvi feels that the DFDBA does not carry this risk, due to the demineralization process. But that is a whole different animal……

      • Tyler
        We are both correct. Allografts are osteoinductive in rats but they are not osteoinductive in humans. I do appreciate your knowledge about the subject of osteoinduction. Because you referenced Lifenet Dr. Ralph Powers is the Senior Product Manager for Lifenet and he will confirm that allografts are not osteoinductive in humans. Greg Steiner Steiner Laboratories

        • Greg,

          This is new and interesting to me. Do you have any literature or evidence you can point me toward that confirms that inductivity in the rat model, but does not illustrate the proof of principle in the human model?

          Tyler

          • Hello Tyler
            Here is a well done study
            J Periodontol. 2001 Aug;72(8):1064-8.
            The osteoinductive potential of demineralized freeze-dried bone allograft in human non-orthotopic sites: a pilot study.
            Paul BF, Horning GM, Hellstein JW, Schafer DR
            You can also see a more complete literature review on our web site. Go to the Steiner Laboratories web site publications tab and scroll down to the title Allografts are not osteoinductive or osteogenic. Like the above article you can copy and paste the papers into Google and the abstract will pop up for your review. There has never been a study that showed allografts to be osteoinductive or osteogenic in humans. Greg Steiner Steiner Laboratories

  11. Greg, you continue to suggest we go to the FDA for explanations, proof of efficacy, or clarification of some of the science. Certainly you can’t be serious, when you use them as your reference? You are parsing words. With regards to the suggestion that only autogenous bone is inductive, there is still some strong data supporting BMP ‘s role as an inductive medium, despite the cooked study results and the rare adversities noted in the cervical reconstruction arena. Bvinci

    • Baker Vinci
      I was only suggesting that clinicians go to the FDA for the definitions of osteoinduction and osteogenesis because very few people understand these terms and that includes many authors, lectures and professors. I agree with you that good science has shown recombinant BMP’s to be osteoinductive because they are pure and highly concentrated. I think allografts are not osteoinductive because of very low concentrations of BMP in combination with the inflammatory reaction to all of the other antigenic proteins included in the transplant of the allograft. Greg Steiner Steiner Laboratories

  12. Greg,

    Interesting article….. I’m sure you and everyone else can appreciate how difficult of a study it is to obtain evidence (or the lack thereof) of osteoinductivity in actual human treatment, both from a study design and an ethics standpoint.

    The authors of the article do state the limitations of their study, mainly the very small sample set, and the use of only one donor lot. Certainly they could have seen radically different results with another lot of DFDBA or with a different study model. Also, it’s not exactly representative of a true test of induction, since the material was placed inside a synthetic housing, which was likely “mobile” during the healing process as most membranes are. Also their “definition” of osteoinductivity is certainly one that is strict, although seemingly accurate.

    Perusing the other available literature, I did find an interesting article regarding osteoinduction, which makes some good points about clinical testing in various animal models.

    Habibovic and De Groot, 2007
    Osteoinductive biomaterials–properties and relevance in bone repair
    J Tissue Eng Regen Med, 1 (2007), pp. 25–32

    Baker do you know of any literature from the spinal orthopedic surgery land that shows induction with Infuse saturated grafts or sponges?

    Mind wide open, and full of skepticism……

    • Tyler, I am certain I can come up with literature to support the inductive properties of BMP in the orthopaedic and neurosurgical literature. Give me a day or two. A friend of mine was their biologics representative for some time and left when it became apparent that there were some unethical things happening. Bvinci

    • We all talk about evidenced based dentistry but with allograft osteoinduction and osteogenesis the profession has put its head in the sand. Lecturers and professors talk about allograft osteoinduction and osteogenesis as if it is fact and when pressed they say yes there is no proof and it is theoretical but they do not talk and write that way and this misleads the clinician. There is no scientific support that allografts are osteoinductive or osteogenic in humans. Some are offended when I challenge their beliefs but I am hopeful that most appreciate an open discussion and the fact that they may know more than those lecturing to them. Greg Steiner Steiner Laboratories

  13. Guys, look at the forest and ignore the trees. Mineralized allografts and xenografts have a long history of success when used with implants. The success rate of implants placed into sinuses and ridges grafted with these materials is comparable to that of implants placed into native bone. Histological studies confirm that there is a bone/implant interface between the graft particles and the implants. So, whether or not the clinical/histological behavior of these materials hews to the FDA definitions of osteoinduction or osteogenicity is immaterial if they are safe, predictable and effective…and they are.

  14. In general, which usually yield better success in grafting a socket for the implant placement in posterior max.? the 50:50 mixed demineralized cortical and cancellous or 50:50 mixed demineralized and mineralized cortical ( or cancellous )
    Please give me your comment. Thanks.

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