A histologic and histomorphometric evaluation of anorganic bovine bone retrieved 9 years after a sinus augmentation procedure.

Background: Anorganic bovine bone (ABB) has been shown to have osteoconductive properties and no inflammatory or adverse responses as grafting materials used in sinus augmentation procedures. Despite these successful results, histologic data in humans over the long-term period are scarce. The purpose of this study was to analyze the histomorphometric data 9 years after surgery in a case of maxillary sinus augmentation using ABB. Methods: The histologic evaluation was pe rformed in flve different thin sections of the specimen, comparing histomorphometric measures for newly formed bone, marrow spaces, biomaterial particles remnants, and number of osteocytes embedded in both trabecular bone and bone tissue near the ABB. The investigation was carried out by means of scanning electron microscopy and brightfield and circularly polarized light microscopy. Results: We observed a mean amount of newly formed bone of 46.0% ± 4.67%, ABB remnants of 16.0% ± 5.89%, and marrow spaces of 38.0% ± 8.93%. The osteocyte index was 4.43 for bone around ABB and 3.27 in the trabecular bone at a distance from the particles. Conclusions: After 9 years, the tissue pattern appeared composed by residual ABB particles in close contact to the newly formed bone. The bone mineralized matrix around the ABB had collagen fibers randomly oriented and more osteocytes embedded. The results demonstrate both a high level of osteoconductivity and a "biomimetic" behavior over the long term.