Studies have shown that the main factor in implant loss is implants placed in sites previously grafted with cadaver bone grafts:
Rehabilitating Sites Grafted WithCadaver Bone Grafts
Early Implant Failure Associated With Patient Factors, Surgical Manipulations, and Systemic Conditions
J Prosthodont. 2019 Jul;28(6):623-633. doi: 10.1111/jopr.12978. Epub 2018 Oct 22.
The risk factors of early implant failure: A retrospective study of 6113 implants
Clin Implant Dent Relat Res. 2021 Jun;23(3):280-288. doi: 10.1111/cid.12992. Epub 2021 Mar 16.
In addition, when an implant is lost in an area previously grafted with a cadaver bone graft, the failure increases for the replacement implant with a failure rate up to 50%:
Successive Reimplantation of Dental Implants Into Sites of Previous Failure
J Oral Maxillofac Surg. 2020 Mar;78(3):375-385. doi: 10.1016/j.joms.2019.10.001. Epub 2019 Oct 13.
Cadaver Bone Grafts and Implant Failure
Cadaver bone grafts produce sclerotic bone, and this area of sclerosis is not limited to just the extraction socket but also involves the bone surrounding the extraction socket. As long as sclerotic bone is present, it does not matter if you immediately replace the failed implant, allow the site to heal after removal of the implant, or place any type of bone graft in the site because the site will always be sclerotic and have a poorer implant success rate than the previous implant.
Because studies have shown that the biggest cause of implant failure is grafting with cadaver bone grafts, it is apparent that we need a method of rehabilitating these sites before another implant is placed.
The following case illustrates how you can rehabilitate a site of a failed implant that had been placed in an extraction socket grafted with a cadaver bone graft.
This implant had been in function for several years. The tooth was extracted and the site was grafted with a mineralized freeze-dried bone allograft. On the mesial of the implant, it is easy to see the granules floating in the granulation tissue.
Granules in the granulation tissue or gingival is pathognomonic for sclerotic bone failure. In periimplantitis, the bone is always resorbed ahead of the infection and there are never any granules in the granulation tissue, and this is one way to distinguish bone graft failure from periimplantitis. Distal to the implant, the bone between the implant and the molar is abnormal in structure, which is indicative of a mineralized cadaver bone graft. Sclerotic bone is also seen at the apex.
Let’s illustrate what this bone looks like clinically:
All cases present differently. In this case, however, the granules of the failed bone graft are easily seen in the granulation tissue, which is definitive proof of sclerotic bone graft failure.
With the implant removed, it is important that the sclerotic bone be completely removed. It is easy to see the difference between sclerotic bone and normal bone. Sclerotic bone is dense, stark white with very little vascularity, and cuts like chalk. In this image on the distal (right) of the socket, bleeding is present, indicating that sclerotic bone has been removed. However, on the mesial (left) of the socket apex, sclerotic bone remains evidenced by the dense white areas of sclerosis and no bleeding. This bone on the mesial needs to be removed. As you can see, there is no clinical evidence of vascular supply in the sclerotic bone.
Lecturers who use cadaver bone always talk about the need to create bleeding for the success of the graft and they are correct when using cadaver bone grafts. When using cadaver bone grafts, the process of bone formation is called antigenic ossification. For antigenic ossification to occur, bleeding is needed for the migration of the inflammatory cells via the blood stream. Mineralization begins on the surface of the allograft particles that are infiltrated with dense lymphocytes. When the cadaver particles are covered with mineralization, the inflammatory infiltrate disappears because the host is now isolated from the foreign material. Once mineralization is complete and sclerotic bone is formed, the vascular supply disappears, and the bone never remodels because this would expose the antigenic inflammatory bone graft particles. Once sclerotic bone is formed, this bone never changes until the sclerotic bone breaks up and the implant is lost.
However, when using SteinerBio Socket Graft or Sinus Graft, the goal is not to create blood flow but to access cancellous bone that contains regenerative cells. The regenerative cells enter our graft material before blood vessels and migrate throughout the graft material and then the vascular supply follows behind. During the removal of the sclerotic tissue, the presence of bleeding indicates that the sclerotic bone has been fully removed and you have reached healthy cancellous bone where regenerative cells can migrate into the graft material.
From this photograph, you can see that the white sclerotic bone has been removed evidenced by bleeding throughout the socket except the lingual cortical bone.
When a socket is grafted with a cadaver bone graft, the area of sclerosis is not limited to the extraction socket where the cadaver bone graft is placed. The area of sclerosis encompasses the majority of the cancellous bone of the alveolar ridge. In this case, the sclerotic bone required removal of virtually all of the cancellous bone between the buccal and lingual cortical ridges and between the teeth. With the need to create such an extensive defect to remove the sclerotic bone, this defect will be slow to heal. In this case, the site was grafted with Socket Graft Plus and covered with a d-PTFE membrane. The implant was replaced after 3 months and has functioned without complication for many years.
Isolated sockets grafted with cadaver bone grafts can be reasonably rehabilitated. However, in cases where sockets and the sinus has been grafted with cadaver bone grafts, there is little to no normal bone. These patients face virtually no options for reliable implant replacement. SteinerBio has been studying bone graft biology for 15 years. We have also watched implant loss in the clinic and we estimate that approximately 50% of all lost implants are the result of bone graft failure of implants placed in cadaver bone grafts.
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