Eight-Year Results of Site Retention of Anorganic Bovine Bone and Anorganic Bovine Matrix
The long-term fate of some biomaterials is still unknown, and the reports present in the literature are not conclusive as to whether these biomaterials are resorbed over time or not. Different reports can be found with regard to the resorption behavior of anorganic bovine bone (ABB). The aim of the present study was to provide a comparative histological and histomorphometrical evaluation, in the same patient, of 2 specimens retrieved from a sinus augmented with ABB and with anorganic bovine matrix added to a cell-binding peptide (PepGen P-15), respectively, after a healing period of 6 months and after 8 years of implant loading, to evaluate the resorption of both biomaterials. A unilateral sinus augmentation procedure with ABB (50%) and with PepGen P-15 (50%) was performed in a 54-year-old male patient. Two titanium dental implants with a sandblasted and acid-etched surface were inserted after 6 months. During this procedure, 2 tissue cores were retrieved from the sinus with a trephine, before implant insertion. After an additional 6 months, a fixed prosthetic restoration was fabricated. One of these implants, after a loading period of 8 years, fractured in the coronal portion and was removed. Both specimens, one retrieved after a 6-month healing period and the other after an 8-year loading period, were treated to obtain thin ground sections. In the 6-month specimen, the histomorphometry showed that the percentage of newly formed bone was 27.2% ± 3.6%, marrow spaces 35.6% ± 2.3%, residual ABB particles 25.1% ± 1.2%, and residual PepGen P-15 particles 12.1% ± 2.2%. In the 8-year specimen, the histomorphometry showed that the percentage of newly formed bone was 51.4% ± 4.8%, marrow spaces 40% ± 7.1%, residual ABB particles 6.2% ± 0.7%, and residual PepGen P-15 particles 2.4% ± 0.5%. Both biomaterials underwent significant resorption over the course of this study.
Figure 1. Panoramic radiograph showing pretreatment sinus anatomy before the regeneration procedure was performed. Figure 2. X-ray showing the sinus after the sinus-lifting procedure. Figure 3. X-ray showing 2 titanium dental implants inserted 6 months after the sinus-lifting procedure. Figure 4. X-ray showing an implant fractured in the coronal portion after an 8-year loading period.
Figure 5. Specimen at 6 months. It is possible to observe the presence of particles of anorganic bovine bone (ABB; lighter particles) and PepGen P-15 (darker particles). Newly formed bone appears to be strongly stained in red with acid fuchsin, and it presents wide osteocyte lacunae. The newly formed bone is mainly in contact with the smaller and larger ABB particles. Some of these ABB particles are completely surrounded by newly formed bone. Only a few particles of Pepgen P-15 are in contact with newly formed bone. Native bone is present on the left of the figure. Acid fuchsin-toluidine blue ×20. Figure 6. Specimen at 6 months. Rims of osteoblasts can be observed deposing osteoid matrix directly on the graft materials surfaces. No osteoclasts are visible. No foreign-body cells and no inflammatory cell infiltrate are present. Acid fuchsin-toluidine blue ×200. Figure 7. Specimen at 8 years. Biomaterial particles are embedded in a compact, mature bone tissue. Most of the ABB particles are completely surrounded by the bone. Some of the PepGen P-15 particles are completely surrounded by bone, while other PepGen P-15 particles are in contact or are lined by small marrow spaces. Acid fuchsin-toluidine blue ×40. Figure 8. Specimen at 8 years. Apical portion of the implant. Small residual particles of both biomaterials are completely embedded in compact, mature bone. Areas of remodeling are present, with some osteons present on the implant surface. Acid fuchsin-toluidine blue ×40.
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