Killing Bacteria Wipes Out Regenerative Cells

In regenerative medicine, there is always a reason for failure. When a bone graft fails and we do not understand why, we are destined to keep on failing. The only way to improve in the clinic is to study our failures until we find the cause. Each time we find the cause, we become better clinicians with more predictable results.

The following case is an example of what we have been preaching for years: Anything you do locally to kill bacteria will wipe out the regenerative cells.

Bacteria are much harder to kill than bone cells. Bacteria will have needed to travel from outside the body in often times hostile environments, before beating back all of our immune defenses in order to start killing our own cells and taking over. Bone cells, on the other hand, are the most protected, pampered cells in our body. They live in a perfectly climate controlled environment bathed in ideal fluids filled with nutrients. Our bone cells are gentle flowers and the bacteria is the Roman Army. Anything you do to kill bacteria in an extraction socket will kill all surrounding bone cells with serious consequences to bone regeneration. One of our primary principals is be kind to the bone or it will punish you.

The following case was a molar extraction site that was grafted with Socket Graft Plus in 2018. For those who do not know, Socket Graft Plus is composed of our osteogenic putty (Socket Graft Injectable) mixed with our 100% beta tricalcium phosphate particles (OsseoConduct). In 2025, the patient returned for an implant, but after flap reflection, the remaining beta TCP particles were found imbedded in dense fibrous tissue. Note the complete lack of vascularity or inflammation.

The defect was filled with residual graft particles embedding in dense fibrous tissue.

The extraction site was filled with dense fibrous tissue with no vascularity encapsulating the beta tricalcium phosphate particles. The fibrous tissue in the case is Type 1 collagen.

After complete debridement of the failed graft, a significant defect remained in the bone with minimal bone formation during the 6 years between socket grafting and surgical exposure.

If you remember your extraction socket healing histology, you remember that healing in the socket goes through stages of fibrin clot, granulation tissue, and formation of a Type 1 collagen plug that then is replaced by bone.

This is an image of the collagen plug found in an untreated socket approximately 4 weeks after extraction.

This is an image of the Type 1 collagen plug being resorbed and replaced by bone at 5 weeks after extraction.

So what is the problem? Why did the graft fail?

The site is filled with type 1 collagen and so why did it not resorb and mineralize? All pertinent records were reviewed and it revealed that when the tooth was extracted in 2018 the socket was treated with a paste of peroxide and clindamycin. The mixture of these 2 products killed all of the bacteria but also killed all of the surrounding bone cells.

When bone is injured, it results in the death of bone cells (such as osteocytes and osteoblasts). This type of injury resulted in the formation of unmineralized fibrosis rather than normal bone for several reasons related to the nature of the injury and the response of the tissue:

Cell Death and Loss of Bone Cells:
- - Without functional osteoblasts, the bone cannot properly regenerate or form the mineralized matrix that is required for normal bone tissue.
Inflammation and Fibrosis Formation:
- - The death of bone cells triggers an inflammatory response, during which fibroblasts are recruited to the injury site. Fibroblasts primarily produce collagen and extracellular matrix components, but are not capable of forming bone.
  - As a result, fibrous tissue (composed mostly of collagen) is laid down instead of bone.

Summary

In essence, when bone cells are killed, the natural process of bone regeneration is disrupted. Since fibroblasts are the primary cell type available to repair the tissue in the absence of osteoblasts, fibrous tissue is formed instead of new, mineralized bone, and that is what caused this graft to fail.

Let’s take this a bit further. The scar tissue in this case was dense Type 1 collagen—the same collagen that is found normal tissue. However, is it the organization of the collagen that makes the difference. In normal tissue, the collagen is very organized but in scar tissue, the collagen is disorganized. In scar tissue, the collagen fibers are randomly arranged and form a dense, cross-linked network, making the tissue stiffer, less functional, and unresorbable and that is why it could not be replaced with bone.

So, in the case presented here, dense scar tissue formed that was never resorbed and caused a scar just like a scar on your skin. In this case, bone cells were killed and a scar tissue was formed without mineralization. But professors and lectures continue to advise the use of toxic materials in sockets when using cadaver bone grafts. This is advised when using cadaver bone grafts because clinicians know that cadaver bone grafts commonly become infected when bacteria is present, so the bacteria must be completely removed. The reason for the propensity of cadaver bone grafts to become infected is due to the macroporosity of the material. When we developed our bone grafts, we took the porosity size of our products into consideration, making sure that the porosity of our materials fell below the size that could potentially become colonized by bacteria. This development made it impossible for bacterial colonization. Therefore, our bone grafts do not require you to kill off the bacteria living in the socket.

The other point is that when you kill the bone cells during the process of killing the bacteria when using a cadaver bone graft, you do get mineralization.

This is the difference:

If using biocompatible bone graft materials:

When you kill the bone cells, you will get unmineralized scar tissue that will never resorb.

If using cadaver bone grafts:

When you kill the bone cells, you will get scar tissue, but it is mineralized scar tissue.

The reason you get mineralization after killing the bone cells with cadaver bone graft is because the foreign proteins in the cadaver bone graft creates inflammation, and the body’s reaction to a foreign object in bone that cannot be resorbed is to isolate the material from the rest of the body by covering it in mineralized tissue.

The takeaway is if you kill the bone cells when using a non-inflammatory biocompatible graft material, you will get dense scar tissue that is not mineralized and not resorbable. If you kill the bone cells using an inflammatory bone graft material, you will get dense scar tissue that is mineralized. Either way, when you kill the bone cells, you will get scar tissue. Either way, you do not want to put an implant into scar tissue.

When using SteinerBio bone grafts materials, you should never put anything in the socket other than sterile saline. Three rinses of sterile saline and evacuating in between each rinse has been shown to significantly reduce the bacteria in the socket. When combining systemic antibiotics with our biocompatible bone grafts, you will not experience bone graft infections irrespective of how infected the site is.

When there is minimal socket infection, our protocol is to remove any granulation tissue and rinse the socket three times with sterile saline, place the graft, and place the patient on 250 mg Amoxicillin for 5 days.

When there is significant infection in the socket, we prescribe 500 mg Amoxicillin for 10 days. Start antibiotics 3 days prior to extraction and graft and 7 days post extraction and graft. This protocol is not to prevent post operative infection, but to reduce the inflammatory damage done to the bone, and allow some time for the regenerative capacity of the bone to recover before extraction.

If it is an infection that is in or near the sinus, our protocol is to prescribe Augmentin 3 days prior to extraction and graft, and 7 days post extraction and graft.

So, when your professors and lecturers explain their socket “sterilization” methods, please understand that they have never used anything other than a 50-year-old graft material and they have no knowledge of regenerative medicine. When a clinician has only used cadaver bone grafts, it is equivalent to a clinician who has only used dental amalgams. Nothing you do with dental amalgam translates into using modern composites. Likewise, nothing you do with cadaver bone grafts translates into using modern regenerative bone graft materials.

MEMBER:

American Society for Bone and Mineral Research (ASBMR)

Tissue Engineering and Regenerative Medicine International Society (TERMIS)

American Academy of Implant Dentistry (AAID)