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Study:
βTCP outperforms Allograft, Xenograft;
authors describe Sclerotic Bone

This was not an easy study to perform, but it was performed very well with clean, clear results. The results are not surprising, but the authors’ understanding of the biology of the various bone grafts studied is what sets this article apart from all others. The study compared a modern βTCP (beta tricalcium phosphate) to a mineralized freeze dried bone allograft and a xenograft (Bio-Oss), including an ungrafted control.

The comparison of different grafts to an ungrafted control is critical when evaluating the performance of a graft material. Many cadaver graft studies do not include ungrafted controls because when evaluating bone formation and bone quality, the ungrafted controls outperform the cadaver bone graft. However, most cadaver bone studies look at maintenance of bone volume, and this where the cadaver bone grafts always outperform the ungrafted controls.

Osseous Healing in Surgically Prepared Bone Defects Using Different Grafting Materials: An Experimental Study in Pigs

Dent J (Basel) 2020 Mar; 8(1): 7. Published online 2020 Jan 9. doi: 10.3390/dj8010007

All particulate grafts have only one purpose: to maintain volume and particulate bone grafts are equivalent for this purpose. Given that all particulate bone grafts (irrespective if they are synthetic or cadaver) maintain volume, this study moved past measuring ridges and set out to find the bone graft that produces the most bone and what kind of bone the different grafts produce. Most previous studies equate bone quality with the amount of new bone produced because the authors lack the ability to distinguish between normal healthy vital bone that has the ability to remodel and adapt, and bone that is pathologic and lacks the ability to remodel and adapt.

The three graft materials were implanted in the skull of a pig, including an ungrafted control, and harvested at 8 and 12 weeks.

3 graft materials implanted in pig skull
Side note: At Steinerbio we have performed similar graft surgeries on rabbits and the surgical skill shown in these photos is remarkable and not easy to do.

The results were definitive. At 8 weeks, there was no statistical difference in bone formation between any group. However, at 12 weeks βTCP was statistically superior to all other groups (see Table 2). There are no studies that have ever shown a cadaver bone graft to be superior to a synthetic no matter how old or poorly performing the synthetic. When comparing cadaver grafts to modern βTCP, the synthetic always significantly outperforms the cadaver graft for bone production, but that is not the important part of this publication. The important part of the publication is the authors’ description of the biologic processes of the various materials.
βTCP superior to allograft and xenograft
At 12 weeks:
  • “It was obvious that βTCP granules were deconstructed to a sufficient degree, with signs of both dissolution of the βTCP particles and direct cellular resorption. These granules were predominantly embedded in the newly formed bone which was more interconnected than at 8 weeks, with signs of bone remodeling.”
  • “In addition, the bovine and human allograft exhibited osseous integration with mature bone, …though particles seemed relatively intact, almost without evidence of absorption and bone substitution.”
These statements are the critical findings. Normal bone resorption and normal bone formation is described for βTCP in addition to the βTCP producing more bone. The authors recognize that cadaver bone does not resorb and there is no bone remodeling evident. This is the definition of sclerotic bone. Not only was there no remodeling of the graft particles, there was no remodeling of the surrounding newly formed bone. When using cadaver bone grafts, the bone present at 12 weeks is permanent and will not remodel for the life of the patient. As we have described in a previous article, as bone ages it weakens and ultimately fails not for lack of mineralization, but by degeneration of the collagen matrix.
Bone News: Recent Findings in Bone Research

Mellonig proposed the theories that allografts produce bone via osteogenesis, osteoinduction and osteoconduction. While all of these theories have been proven wrong, many professors and clinicians in the US still cling to the false narrative. What is amazing in the US is that while most professors and clinicians limit their research and clinical use to cadaver bone grafts, they still cannot describe how these materials produce bone and are unable to see that the bone produced by cadaver bone grafts is pathologic.

The authors in this study are different for two reasons:

First and foremost, one of the authors is a pathologist. A pathologist is trained to see and understand bone pathology and they see the bone pathology found in osteoarthritis and understand sclerotic bone. While there are hundreds of cadaver histologic studies virtually none of them accurately describe the bone produced because the authors lack the knowledge to understand what they are seeing. Dentists have no training in bone pathology and none of our professors or lectures can tell the difference between woven and sclerotic bone. We are aware of only two other instances where the quality of bone produced by cadaver bone grafts is accuracy described in the literature.

The first accurate description of the pathologic bone produced by cadaver bone grafts was made by none other than Marshall Urist, the orthopedic surgeon/scientist who discovered BMP. Urist was working with dentists at USC and published the following article:

Histologic findings after implantation and evaluation of different grafting materials and titanium micro screws into extraction sockets: case reports
Becker, W., Clokie, C., Sennerby, L., Urist, M.R. and Becker, B.E. (1998)
  • “The over-riding histologic characteristic of sites implanted with DFDBA or MFDBA was retention of non-vital graft particles within fibrous connective tissue.”
  • “DFDBA and MFDBA are resorbed very slowly and apparently do not contribute to osteoinduction. Allografts apparently are not resorbed by osteoclasts and therefore their continued use around dental implants is questioned.”
The first article to actually state that cadaver bone grafts produce sclerotic bone was made by Dr. Richard Jordon a pathologist at UCSF working with two oral surgeons:

Alveolar ridge augmentation: comparison of two socket graft materials in implant cases

Tolstunov L, Chi j. Compend Contin Educ Dent. 2011 Nov-Dec;32(9):E146-55. PMID: 23627308.

The second reason why the authors of the current study were able to accurately describe the bone produced by cadaver bone grafts is because they have read our preprint articles on sclerotic bone. We know because they referenced one of our preprints.

Preprint articles were created for research that the established journals refuse to publish, but now many research articles are first published in preprint form to speed the dissemination of information and act as a placeholder for the introduction of ground-breaking knowledge. Our preprint articles were rejected by peer reviewers of mainstream journals, though not on scientific grounds as we only received angry rejection notices citing the audacity to attempt to publish something negative about cadaver bone grafts.

That was many years ago, but now that the profession is recognizing a higher failure rate in sites grafted with cadaver bone grafts and they are looking for an explanation. Well done studies are finding that the only statistically significant variable related to implant loss is grafting sockets with cadaver bone grafts.

However, with the publication of studies that find grafting with cadaver bone grafts are the only statistical significant variable for implant loss (Two Studies Find One Reason for Implant Failure) and the profession’s recognition that bone graft failure is real, when they look for answers they are finding our preprints:

Modern science-based bone graft materials always outperform cadaver bone grafts when the amount of bone produced and the quality of the bone is evaluated. Science-based bone grafts have long term implant studies to support their use in sockets and cadaver bone graft do not. So why in the US do the majority of clinicians use cadaver bone graft? The biggest reason is because all of the US professors and lecturers only know how to teach and use cadaver bone grafts and because our profession in the US has accepted cadaver bone grafts as superior for decades. As a result, unfortunately, our profession has made no progress on furthering our understanding of bone biology and have completely ignored bone graft biology. This is not the case in Europe and Asia where allografts are not favored. As a result, bone graft knowledge in Europe and Asia has advanced beyond our knowledge.

Another reason why inferior cadaver bone grafts are still popular is because of the image below:
clinical appearance of βTCP, allograft, and xenograft
When a dentist opens a graft site, he wants to see what he thinks is hard bone. Because cadaver grafts look like bone, this is perceived as superior even though there is more residual cadaver bone and less new bone present. As you can see in the above the site grafted with the βTCP, the granules are obvious and dentists thinks this is inferior. We get calls from customers who question our graft materials because they see particles when they open their flaps. We explain that while resorption is occurring, rapid resorption will not begin until the site is loaded with an implant and at that time, all of the graft material will be replaced with healthy vital bone. This does not happen with cadaver bone grafts. See the table below:
results of histomorphometric analysis of newly formed bone

In the discussion, the authors provided a literature review to support their findings:

“A systematic review analyzed the outcomes of randomized controlled trials of socket grafting procedures performed with flapless extraction of teeth after a minimum healing period of 12 weeks. The mean histologic outcomes at or beyond the 12-week re-entry period revealed the highest vital bone content for sockets grafted with alloplasts, followed by sockets with no graft material, xenografts, and allografts.”

In another study, βTCP at 8 weeks produced more bone than autograft:

In reference to the study’s findings regarding a lack of bone remodeling with cadaver bone grafts the authors state the following with the following reference:

“As to bovine and human allograft used in our project, new bone formation was found to be less compared to βTCP, possibly due to the slow resorption rate of the formers. These results reconfirm previous findings that long-term presence of residual non-resorbable or slowly resorbable particles of the graft might deregulate bone healing and the remodeling mechanism depending on the biodegradation pattern, having negative results on the overall quality, quantity, and architecture of the reconstructed bone”.

The authors clearly describe sclerotic bone with the following statement and references:

“According to another possible explanation, freeze-dried mineralized human allografts, like in our project, exhibit a slow rate of biodegradation and remain trapped within the surrounding newly formed bone, while after mineralization, resorption capability is suspended.”

For studies that include a βTCP, cadaver bone graft and a empty control the results are always the same. βTCP produces more bone and is remodeled into normal bone. These findings are the same findings that was produced with our own GLP study using rabbit tibia:
GLP study of bone grafts using rabbit tibia
We are continually amazed at how our profession continually professes evidence based dentistry, but completely ignores the science when it comes to bone grafting.

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