Expression of MMP-2, 9 and 13 in newly formed bone after sinus augmentation using inorganic bovine bone in human
Résumé
Background and Objective: The aim of the present study was to analyse the expression of MMP-2, MMP-9 and MMP-13 in newly formed bone following maxillary sinus augmentation using inorganic bovine bone substitute, because these MMPs play a major role in bone remodeling and bone resorption. Material and Methods: Deproteinized bovine bone (Bio-Oss (R)) was used to fill cavities after elevating the sinus mucosa. Twenty patients with edentulous posterior maxilla were treated with 20 sinus-augmentation procedures using a two-stage technique. Forty-nine Straumann (R) endosseous implants were used to complete the implant-prosthetic rehabilitation. One cylinder-shaped bone biopsy from each patient was taken from the augmented maxillary region using trephine burs at the second stage of surgery, 8 months after grafting. A biopsy was also taken as a control from the upper molar region from six different patients who did not undergo the sinus procedure. All biopsies were subjected to biochemical analysis and staining for TRAP. Results: No implant losses or failures occurred. The large number of TRAP-positive multinucleated osteoclasts in resorption lacunae indicated that the resorption was very active in all grafts, in contrast with the control group. Zymography and western blot analysis demonstrated a significantly increased expression of MMP-2, MMP-9 and MMP-13 in the newly formed bone compared with controls (p < 0.05). Conclusion: The quantity of osteoclastic cells and the increased expression of proteolytic enzymes suggest that 8 months after grafting, inorganic bovine bone is slowly resorbing and is the site of important remodeling of the newly formed bone by means of resorption and synthesis.